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Author: Grafiati
Published: 14 March 2023

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1

Gao, Miaomiao, Kaili Nie, Meng Qin, Haijun Xu, Fang Wang, and Luo Liu. "Molecular Mechanism Study on Stereo-Selectivity of α or β Hydroxysteroid Dehydrogenases." Crystals 11, no. 3 (February 25, 2021): 224. http://dx.doi.org/10.3390/cryst11030224.

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Hydroxysteroid dehydrogenases (HSDHs) are from two superfamilies of short-chain dehydrogenase (SDR) and aldo–keto reductase (AKR). The HSDHs were summarized and classified according to their structural and functional differences. A typical pair of enzymes, 7α–hydroxysteroid dehydrogenase (7α–HSDH) and 7β–hydroxysteroid dehydrogenase (7β–HSDH), have been reported before. Molecular docking of 7-keto–lithocholic acid(7–KLA) to the binary of 7β–HSDH and nicotinamide adenine dinucleotide phosphate (NADP+) was realized via YASARA, and a possible binding model of 7β–HSDH and 7–KLA was obtained. The α side of 7–KLA towards NADP+ in 7β–HSDH, while the β side of 7–KLA towards nicotinamide adenine dinucleotide (NAD+) in 7α–HSDH, made the orientations of C7–OH different in products. The interaction between Ser193 and pyrophosphate of NAD(P)+ [Ser193–OG⋯3.11Å⋯O1N–PN] caused the upturning of PN–phosphate group, which formed a barrier with the side chain of His95 to make 7–KLA only able to bind to 7β–HSDH with α side towards nicotinamide of NADP+. A possible interaction of Tyr253 and C24 of 7–KLA may contribute to the formation of substrate binding orientation in 7β–HSDH. The results of sequence alignment showed the conservation of His95, Ser193, and Tyr253 in 7β–HSDHs, exhibiting a significant difference to 7α–HSDHs. The molecular docking of other two enzymes, 17β–HSDH from the SDR superfamily and 3(17)α–HSDH from the AKR superfamily, has furtherly verified that the stereospecificity of HSDHs was related to the substrate binding orientation.
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2

Viles, John H., Mark Klewpatinond, and Rebecca C. Nadal. "Copper and the structural biology of the prion protein." Biochemical Society Transactions 36, no. 6 (November 19, 2008): 1288–92. http://dx.doi.org/10.1042/bst0361288.

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PrP (prion-related protein) is a cell-surface Cu2+-binding glycoprotein which, when misfolded, is responsible for a number of transmissible spongiform encephalopathies. The co-ordination geometry, stoichiometry and affinity of Cu2+ for PrP are the subject of much debate. In the present paper, we review the recent progress we have made in these areas. As many as six Cu2+ ions bind to PrP with submicromolar affinity. Initially, two Cu2+ ions bind to full-length PrP in the amyloidogenic region, between the octarepeats and the structured domain, at His95 and His110. Only subsequent Cu2+ ions bind to single histidine residues within the octarepeat region. Competitive chelators have been used to determine the affinity of the first molar equivalent of Cu2+ bound to full-length PrP; this approach places the affinity in the nanomolar range. The affinity and number of Cu2+-binding sites support the suggestion that PrP could act as an antioxidant by binding potentially harmful Cu2+ ions and sacrificially quenching of free radicals generated as a result of copper redox cycling. Finally, the effect of Cu2+ on the prion structure and misassembly into oligomers and fibres is discussed.
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3

Bsat, Nada, and John D. Helmann. "Interaction of Bacillus subtilis Fur (Ferric Uptake Repressor) with the dhb Operator In Vitro and In Vivo." Journal of Bacteriology 181, no. 14 (July 15, 1999): 4299–307. http://dx.doi.org/10.1128/jb.181.14.4299-4307.1999.

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ABSTRACT Bacillus subtilis contains three metalloregulatory proteins belonging to the ferric uptake repressor (Fur) family: Fur, Zur, and PerR. We have overproduced and purified Fur protein and analyzed its interaction with the operator region controlling the expression of the dihydroxybenzoate siderophore biosynthesis (dhb) operon. The purified protein binds with high affinity and selectivity to the dhb regulatory region. DNA binding does not require added iron, nor is binding reduced by dialysis of Fur against EDTA or treatment with Chelex. Fur selectively inhibits transcription from the dhb promoter by ςA RNA polymerase, even if Fur is added after RNA polymerase holoenzyme. Since neither DNA binding nor inhibition of transcription requires the addition of ferrous ion in vitro, the mechanism by which iron regulates Fur function in vivo is not obvious. Mutagenesis of the furgene reveals that in vivo repression of the dhb operon by iron requires His97, a residue thought to be involved in iron sensing in other Fur homologs. Moreover, we identify His96 as a second likely iron ligand, since a His96Ala mutant mediates repression at 50 μM but not at 5 μM iron. Our data lead us to suggest that Fur is able to bind DNA independently of bound iron and that the in vivo role of iron is to counteract the effect of an inhibitory factor, perhaps another metal ion, that antagonizes this DNA-binding activity.
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4

Wang, Xixi, Jiankai Shan, Wei Liu, Jing Li, Hongwei Tan, Xichen Li, and Guangju Chen. "Theoretical Studies on the Binding Mode and Reaction Mechanism of TLP Hydrolase kpHIUH." Molecules 26, no. 13 (June 25, 2021): 3884. http://dx.doi.org/10.3390/molecules26133884.

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In this work, we have investigated the binding conformations of the substrate in the active site of 5-HIU hydrolase kpHIUH and its catalytic hydrolysis mechanism. Docking calculations revealed that the substrate adopts a conformation in the active site with its molecular plane laying parallel to the binding interface of the protein dimer of kpHIUH, in which His7 and His92 are located adjacent to the hydrolysis site C6 and have hydrogen bond interactions with the lytic water. Based on this binding conformation, density functional theory calculations indicated that the optimal catalytic mechanism consists of two stages: (1) the lytic water molecule is deprotonated by His92 and carries out nucleophilic attack on C6=O of 5-HIU, resulting in an oxyanion intermediate; (2) by accepting a proton transferred from His92, C6–N5 bond is cleaved to completes the catalytic cycle. The roles of His7, His92, Ser108 and Arg49 in the catalytic reaction were revealed and discussed in detail.
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5

Sanyanga, Taremekedzwa Allan, Bilal Nizami, and Özlem Tastan Bishop. "Mechanism of Action of Non-Synonymous Single Nucleotide Variations Associated with α-Carbonic Anhydrase II Deficiency." Molecules 24, no. 21 (November 4, 2019): 3987. http://dx.doi.org/10.3390/molecules24213987.

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Human carbonic anhydrase II (CA-II) is a Zinc (Zn 2 + ) metalloenzyme responsible for maintenance of acid-base balance within the body through the reversible hydration of CO 2 to produce protons (H + ) and bicarbonate (BCT). Due to its importance, alterations to the amino acid sequence of the protein as a result of single nucleotide variations (nsSNVs) have detrimental effects on homeostasis. Six pathogenic CA-II nsSNVs, K18E, K18Q, H107Y, P236H, P236R and N252D were identified, and variant protein models calculated using homology modeling. The effect of each nsSNV was analyzed using motif analysis, molecular dynamics (MD) simulations, principal component (PCA) and dynamic residue network (DRN) analysis. Motif analysis identified 11 functionally important motifs in CA-II. RMSD data indicated subtle SNV effects, while PCA analysis revealed that the presence of BCT results in greater conformational sampling and free energy in proteins. DRN analysis showed variant allosteric effects, and the average betweenness centrality (BC) calculations identified Glu117 as the most important residue for communication in CA-II. The presence of BCT was associated with a reduction to Glu117 usage in all variants, suggesting implications for Zn 2 + dissociation from the CA-II active site. In addition, reductions to Glu117 usage are associated with increases in the usage of the primary and secondary Zn 2 + ligands; His94, His96, His119 and Asn243 highlighting potential compensatory mechanisms to maintain Zn 2 + within the active site. Compared to traditional MD simulation investigation, DRN analysis provided greater insights into SNV mechanism of action, indicating its importance for the study of missense mutation effects in proteins and, in broader terms, precision medicine related research.
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6

Hempelmann, Franziska, Soraya Hölper, Mirka-Kristin Verhoefen, Andreas C. Woerner, Thomas Köhler, Sarah-Anna Fiedler, Nicole Pfleger, Josef Wachtveitl, and Clemens Glaubitz. "His75−Asp97 Cluster in Green Proteorhodopsin." Journal of the American Chemical Society 133, no. 12 (March 30, 2011): 4645–54. http://dx.doi.org/10.1021/ja111116a.

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7

Tanley, Simon W. M., Antoine M. M. Schreurs, Loes M. J. Kroon-Batenburg, and John R. Helliwell. "Room-temperature X-ray diffraction studies of cisplatin and carboplatin binding to His15 of HEWL after prolonged chemical exposure." Acta Crystallographica Section F Structural Biology and Crystallization Communications 68, no. 11 (October 26, 2012): 1300–1306. http://dx.doi.org/10.1107/s1744309112042005.

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The anticancer complexes cisplatin and carboplatin are known to bind to both the Nδand the N∊atoms of His15 of hen egg-white lysozyme (HEWL) in the presence of dimethyl sulfoxide (DMSO). However, neither binds in aqueous media after 4 d of crystallization and crystal growth, suggesting that DMSO facilitates cisplatin/carboplatin binding to the N atoms of His15 by an unknown mechanism. Crystals of HEWL cocrystallized with cisplatin in both aqueous and DMSO media, of HEWL cocrystallized with carboplatin in DMSO medium and of HEWL cocrystallized with cisplatin andN-acetylglucosamine (NAG) in DMSO medium were stored for between seven and 15 months. X-ray diffraction studies of these crystals were carried out on a Bruker APEX II home-source diffractometer at room temperature. Room-temperature X-ray diffraction data collection removed the need for cryoprotectants to be used, ruling out any effect that the cryoprotectants might have had on binding to the protein. Both cisplatin and carboplatin still bind to both the Nδand N∊atoms of His15 in DMSO media as expected, but more detail for the cyclobutanedicarboxylate (CBDC) moiety of carboplatin was observed at the N∊binding site. However, two molecules of cisplatin were now observed to be bound to His15 in aqueous conditions. The platinum peak positions were identified using anomalous difference electron-density maps as a cross-check withFo−FcOMIT electron-density maps. The occupancies of each binding site were calculated usingSHELXTL. These results show that over time cisplatin binds to both N atoms of His15 of HEWL in aqueous media, whereas this binding is speeded up in the presence of DMSO. The implication of cisplatin binding to proteins after a prolonged period of time is an important consideration for the length of treatment in patients who are given cisplatin.
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8

Plowman, Jeffrey E., and Lawrence K. Creamer. "Restrained molecular dynamics study of the interaction between bovine κ-casein peptide 98–111 and bovine chymosin and porcine pepsin." Journal of Dairy Research 62, no. 3 (August 1995): 451–67. http://dx.doi.org/10.1017/s0022029900031150.

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SummaryThe cleavage of bovine κ-casein at the Phe105–Met106* bond by chymosin or pepsin is the first stage in casein micelle coagulation and casein digestion. The nature of the interaction of the peptide His98–Pro–His–Pro–His–Leu–Ser–Phe105–Met–Ala–Ile–Pro-Pro-Lys111 with chymosin and porcine pepsin was investigated using molecular modelling and energy minimization techniques. This study verified and extended a proposed model that electrostatic binding (involving His98, His100, His102 and Lys111 or Lys112) at either end of the active site cleft of chymosin is important for the positioning of residues 103–108 in the cleft. The peptide conformation remained unchanged in going from solution to binding into the active site cleft, with the exception that optimum binding of substrate to chymosin required the isomerization of the His98–Pro99 peptide bond from the trans to the cis conformation. The study also identified an acidic region in porcine pepsin that is in a position to form strong electrostatic interactions with the histidines at the N-terminus of the peptide.
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9

Ni, Jie, Guochao Xu, Wei Dai, Yi-Lei Zhao, and Ye Ni. "Hyperconjugation promoted by hydrogen bonding between His98/His241 and a carboxyl group contributes to tyrosine decarboxylase catalysis." Catalysis Science & Technology 9, no. 22 (2019): 6222–26. http://dx.doi.org/10.1039/c9cy01290g.

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10

Ishikawa, Yasuko, Tomasz D. Pieczonka, Aneta M. Bragiel-Pieczonka, Harumichi Seta, Tadahiro Ohkuri, Yumi Sasanuma, and Yuji Nonaka. "Long-Term Oral Administration of LLHK, LHK, and HK Alters Gene Expression Profile and Restores Age-Dependent Atrophy and Dysfunction of Rat Salivary Glands." Biomedicines 8, no. 2 (February 20, 2020): 38. http://dx.doi.org/10.3390/biomedicines8020038.

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Xerostomia, also known as dry mouth, is caused by a reduction in salivary secretion and by changes in the composition of saliva associated with the malfunction of salivary glands. Xerostomia decreases quality of life. In the present study, we investigated the effects of peptides derived from β-lactoglobulin C on age-dependent atrophy, gene expression profiles, and the dysfunction of salivary glands. Long-term oral administration of Leu57-Leu58-His59-Lys60 (LLHK), Leu58-His59-Lys60 (LHK) and His59-Lys60 (HK) peptides induced salivary secretion and prevented and/or reversed the age-dependent atrophy of salivary glands in older rats. The transcripts of 78 genes were upregulated and those of 81 genes were downregulated by more than 2.0-fold (p ≤ 0.05) after LHK treatment. LHK upregulated major salivary protein genes such as proline-rich proteins (Prpmp5, Prb3, Prp2, Prb1, Prp15), cystatins (Cst5, Cyss, Vegp2), amylases (Amy1a, Amy2a3), and lysozyme (Lyzl1), suggesting that LLHK, LHK, and HK restored normal salivary function. The AP-2 transcription factor gene (Tcfap2b) was also induced significantly by LHK treatment. These results suggest that LLHK, LHK, and HK-administration may prevent and/or reverse the age-dependent atrophy and functional decline of salivary glands by affecting gene expression.
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11

de Cristóbal, Ricardo E., Jose O. Solbiati, Ana M. Zenoff, Paula A. Vincent, Raul A. Salomón, Julia Yuzenkova, Konstantin Severinov, and Ricardo N. Farías. "Microcin J25 Uptake: His5 of the MccJ25 Lariat Ring Is Involved in Interaction with the Inner Membrane MccJ25 Transporter Protein SbmA." Journal of Bacteriology 188, no. 9 (May 1, 2006): 3324–28. http://dx.doi.org/10.1128/jb.188.9.3324-3328.2006.

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ABSTRACT Escherichia coli microcin J25 (MccJ25) is a plasmid-encoded antibiotic peptide consisting of 21 l-amino acid residues (G1-G-A-G-H5-V-P-E-Y-F10-V-G-I-G-T15-P-I-S-F-Y20-G). E. coli RNA polymerase (RNAP) is the intracellular target of MccJ25. MccJ25 enters cells after binding to specific membrane transporters: FhuA in the outer membrane and SbmA in the inner membrane. Here, we studied MccJ25 mutants carrying a substitution of His5 by Lys, Arg, or Ala. The inhibitory effects on cellular growth and in vitro RNAP activity were determined for each mutant microcin. The results show that all mutants inhibited RNAP in vitro. However, the mutants were defective in their ability to inhibit cellular growth. Experiments in which the FhuA protein was bypassed showed that substitutions of MccJ25 His5 affected the SbmA-dependent transport. Our results thus suggest that MccJ25 His5 located in the lariat ring is involved, directly or indirectly, in specific interaction with SbmA and is not required for MccJ25 inhibition of RNAP.
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12

HO, Heng-Chien, and Ta-Hsiu LIAO. "Protein structure and gene cloning of Syncephalastrum racemosum nuclease." Biochemical Journal 339, no. 2 (April 8, 1999): 261–67. http://dx.doi.org/10.1042/bj3390261.

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The complete amino acid sequence of the fungus Syncephalastrum racemosum (Sr-) nuclease has been delineated on the basis of protein sequencing of the intact protein and its protease-digested peptides. The resulting 250-residue sequence shows a carbohydrate side chain attached at Asn134 and two half-cystine residues (Cys242 and Cys247) cross-linked to form a small disulphide loop. On the basis of the sequence of Sr-nuclease, a computer search in the sequence database yielded 60% and 48% positional identities with the sequences of Cunninghamella echinulata nuclease C1 and yeast mitochondria nuclease respectively, and very little similarity to those of several known mammalian DNases I. Sequence alignment of the three similar nucleases reveals that the single small disulphide loop is unchanged but the carbohydrate attachment in Sr-nuclease is absent from the other two nucleases. Alignment also shows a highly conserved region harbouring Sr-nuclease His85, which is assigned as one of the essential residues in the active site. The cDNA encoding Sr-nuclease was amplified by using reverse transcriptase-mediated PCR with degenerate primers based on its amino acid sequence. Subsequently, specific primers were synthesized for use in the 3´ and 5´ rapid amplification of cDNA ends (RACE). Direct sequencing of the RACE products led to the deduction of a 1.1 kb cDNA sequence for Sr-nuclease. The cDNA contains an open reading frame of 320 amino acid residues including a 70-residue putative signal peptide and the 250-residue mature protein. Finally, the recombinant Sr-nuclease was expressed in Escherichia coli strain BL21(DE3) in which the recombinant protein, after solubilization with detergent and renaturation, showed both DNase and RNase activities. The assignment of His85 to the active site was further supported by evidence that the mutant protein Sr-nuclease (H85A), in which His85 was replaced by Ala, was not able to degrade DNA or RNA.
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13

Gras, Stephanie, Zhenjun Chen, John J. Miles, Yu Chih Liu, Melissa J. Bell, Lucy C. Sullivan, Lars Kjer-Nielsen, et al. "Allelic polymorphism in the T cell receptor and its impact on immune responses." Journal of Experimental Medicine 207, no. 7 (June 21, 2010): 1555–67. http://dx.doi.org/10.1084/jem.20100603.

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In comparison to human leukocyte antigen (HLA) polymorphism, the impact of allelic sequence variation within T cell receptor (TCR) loci is much less understood. Particular TCR loci have been associated with autoimmunity, but the molecular basis for this phenomenon is undefined. We examined the T cell response to an HLA-B*3501–restricted epitope (HPVGEADYFEY) from Epstein-Barr virus (EBV), which is frequently dominated by a TRBV9*01+ public TCR (TK3). However, the common allelic variant TRBV9*02, which differs by a single amino acid near the CDR2β loop (Gln55→His55), was never used in this response. The structure of the TK3 TCR, its allelic variant, and a nonnaturally occurring mutant (Gln55→Ala55) in complex with HLA-B*3501HPVGEADYFEY revealed that the Gln55→His55 polymorphism affected the charge complementarity at the TCR–peptide-MHC interface, resulting in reduced functional recognition of the cognate and naturally occurring variants of this EBV peptide. Thus, polymorphism in the TCR loci may contribute toward variability in immune responses and the outcome of infection.
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14

Ran, Tingting, Gabriel Ozorowski, Yanyan Gao, Oleg A. Sineshchekov, Weiwu Wang, John L. Spudich, and Hartmut Luecke. "Cross-protomer interaction with the photoactive site in oligomeric proteorhodopsin complexes." Acta Crystallographica Section D Biological Crystallography 69, no. 10 (September 20, 2013): 1965–80. http://dx.doi.org/10.1107/s0907444913017575.

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Proteorhodopsins (PRs), members of the microbial rhodopsin superfamily of seven-transmembrane-helix proteins that use retinal chromophores, comprise the largest subfamily of rhodopsins, yet very little structural information is available. PRs are ubiquitous throughout the biosphere and their genes have been sequenced in numerous species of bacteria. They have been shown to exhibit ion-pumping activity like their archaeal homolog bacteriorhodopsin (BR). Here, the first crystal structure of a proteorhodopsin, that of a blue-light-absorbing proteorhodopsin (BPR) isolated from the Mediterranean Sea at a depth of 12 m (Med12BPR), is reported. Six molecules ofMed12BPR form a doughnut-shapedC6hexameric ring, unlike BR, which forms a trimer. Furthermore, the structures of two mutants of a related BPR isolated from the Pacific Ocean near Hawaii at a depth of 75 m (HOT75BPR), which show aC5pentameric arrangement, are reported. In all three structures the retinal polyene chain is shifted towards helixCwhen compared with other microbial rhodopsins, and the putative proton-release group in BPR differs significantly from those of BR and xanthorhodopsin (XR). The most striking feature of proteorhodopsin is the position of the conserved active-site histidine (His75, also found in XR), which forms a hydrogen bond to the proton acceptor from the same molecule (Asp97) and also to Trp34 of a neighboring protomer. Trp34 may function by stabilizing His75 in a conformation that favors a deprotonated Asp97 in the dark state, and suggests cooperative behavior between protomers when the protein is in an oligomeric form. Mutation-induced alterations in proton transfers in the BPR photocycle inEscherichia colicells provide evidence for a similar cross-protomer interaction of BPR in living cells and a functional role of the inter-protomer Trp34–His75 interaction in ion transport. Finally, Wat402, a key molecule responsible for proton translocation between the Schiff base and the proton acceptor in BR, appears to be absent in PR, suggesting that the ion-transfer mechanism may differ between PR and BR.
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15

Funhoff, Enrico G., Yunling Wang, Goran Andersson, and Bruce A. Averill. "Substrate positioning by His92 is important in catalysis by purple acid phosphatase." FEBS Journal 272, no. 12 (June 14, 2005): 2968–77. http://dx.doi.org/10.1111/j.1742-4658.2005.04686.x.

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16

Yang, X., Y. Li, L. Huang, X. Zhang, C. Cheng, H. Gong, L. Ma, and K. Huang. "Diethylpyrocarbonate modification reveals HisB5 as an important modulator of insulin amyloid formation." Journal of Biochemistry 157, no. 1 (August 28, 2014): 45–51. http://dx.doi.org/10.1093/jb/mvu052.

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17

Liu, Wen, Corina E. Rogge, Giordano F. Z. da Silva, Vladimir P. Shinkarev, Ah-Lim Tsai, Yury Kamensky, Graham Palmer, and Richard J. Kulmacz. "His92 and His110 selectively affect different heme centers of adrenal cytochrome b561." Biochimica et Biophysica Acta (BBA) - Bioenergetics 1777, no. 9 (September 2008): 1218–28. http://dx.doi.org/10.1016/j.bbabio.2008.04.039.

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18

Tanley, Simon W. M., Antoine M. M. Schreurs, Loes M. J. Kroon-Batenburg, and John R. Helliwell. "Re-refinement of 4g4a: room-temperature X-ray diffraction study of cisplatin and its binding to His15 of HEWL after 14 months chemical exposure in the presence of DMSO." Acta Crystallographica Section F Structural Biology Communications 72, no. 3 (February 19, 2016): 253–54. http://dx.doi.org/10.1107/s2053230x16000856.

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A re-refinement of 4g4a, the room-temperature X-ray diffraction study of cisplatin and its binding to His15 of HEWL after 14 months chemical exposure in the presence of DMSO is published as an addendum to Tanleyet al.[(2012),Acta Cryst.F68, 1300–1306]. This example illustrates the benefits of sharing raw diffraction images, as well as structure factors and molecular coordinates, as the diffraction resolution of the study is now much improved at 1.70 Å.
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19

Castro Torres, Mario Eduardo, Pablo Marcelo Vargas-Piérola, Carlos F. Pinto, and Rubén Alvarado. "Serial Mediation Model of Social Capital Effects over Academic Stress in University Students." European Journal of Investigation in Health, Psychology and Education 12, no. 11 (November 16, 2022): 1644–56. http://dx.doi.org/10.3390/ejihpe12110115.

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Background: Although several studies have shown that social capital and social support decreases academic stress (AS), there has been lack of atheoretical model to explain how this occurs. This study aims to verify a model that explains the effect of bonding social capital (BSC) over academic stress psychological symptoms (PsyS), considering the multiple sequential mediation of socio-emotional support (SES), self-efficacy (sEffic) and self-esteem (sEstee). Methods: In a transversal study, 150 undergraduate volunteer students were recruited using non-probabilistic purposive sampling. Data were collected using psychological questionnaires and were processed through partial least squares structural equation modeling (PLS-SEM). Results: Goodness of fit of the models (SRMR = 0.056, 0.057, <HI95) (dULS, dG < HI95), reliability and validity are adequate. The indirect effect of BSC over PsyS (β = −0.196; IC 95% [−0.297, −0.098]) is relevant and significant and is serial mediated by SES and sEffic. Conclusions: From a very precise conceptual definition, a model is generated, within which empirical evidence explains the relationship between BSC and PsyS, emphasizing the role of BSC in the development of personal resources to cope with AS. This can be applied to policies and public health programs that affect these variables.
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20

Zhang, Liang, Jacqueline Wax, Renliang Huang, Frank Petersen, and Xinhua Yu. "Meta-Analysis and Systematic Review of the Association between a Hypoactive NCF1 Variant and Various Autoimmune Diseases." Antioxidants 11, no. 8 (August 16, 2022): 1589. http://dx.doi.org/10.3390/antiox11081589.

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Genetic association studies have discovered the GTF2I-NCF1 intergenic region as a strong susceptibility locus for multiple autoimmune disorders, with the missense mutation NCF1 rs201802880 as the causal polymorphism. In this work, we aimed to perform a comprehensive meta-analysis of the association of the GTF2I-NCF1 locus with various autoimmune diseases and to provide a systemic review on potential mechanisms underlying the effect of the causal NCF1 risk variants. The frequencies of the two most extensively investigated polymorphisms within the locus, GTF2I rs117026326 and NCF1 rs201802880, vary remarkably across the world, with the highest frequencies in East Asian populations. Meta-analysis showed that the GTF2I-NCF1 locus is significantly associated with primary Sjögren’s syndrome, systemic lupus erythematosus, systemic sclerosis, and neuromyelitis optica spectrum disorder. The causal NCF1 rs201802880 polymorphism leads to an amino acid substitution of p.Arg90His in the p47phox subunit of the phagocyte NADPH oxidase. The autoimmune disease risk His90 variant results in a reduced ROS production in phagocytes. Clinical and experimental evidence shows that the hypoactive His90 variant might contribute to the development of autoimmune disorders via multiple mechanisms, including impairing the clearance of apoptotic cells, regulating the mitochondria ROS-associated formation of neutrophil extracellular traps, promoting the activation and differentiation of autoreactive T cells, and enhancing type I IFN responses. In conclusion, the identification of the association of NCF1 with autoimmune disorders demonstrates that ROS is an essential regulator of immune tolerance and autoimmunity mediated disease manifestations.
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Magrì, Antonio, Giovanni Tabbì, Irina Naletova, Francesco Attanasio, Giuseppe Arena, and Enrico Rizzarelli. "A Deeper Insight in Metal Binding to the hCtr1 N-terminus Fragment: Affinity, Speciation and Binding Mode of Binuclear Cu2+ and Mononuclear Ag+ Complex Species." International Journal of Molecular Sciences 23, no. 6 (March 8, 2022): 2929. http://dx.doi.org/10.3390/ijms23062929.

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Ctr1 regulates copper uptake and its intracellular distribution. The first 14 amino acid sequence of the Ctr1 ectodomain Ctr1(1-14) encompasses the characteristic Amino Terminal Cu2+ and Ni2+ binding motif (ATCUN) as well as the bis-His binding motif (His5 and His6). We report a combined thermodynamic and spectroscopic (UV-vis, CD, EPR) study dealing with the formation of Cu2+ homobinuclear complexes with Ctr1(1-14), the percentage of which is not negligible even in the presence of a small Cu2+ excess and clearly prevails at a M/L ratio of 1.9. Ascorbate fails to reduce Cu2+ when bound to the ATCUN motif, while it reduces Cu2+ when bound to the His5-His6 motif involved in the formation of binuclear species. The histidine diade characterizes the second binding site and is thought to be responsible for ascorbate oxidation. Binding constants and speciation of Ag+ complexes with Ctr1(1-14), which are assumed to mimic Cu+ interaction with N-terminus of Ctr1(1-14), were also determined. A preliminary immunoblot assay evidences that the anti-Ctr1 extracellular antibody recognizes Ctr1(1-14) in a different way from the longer Ctr1(1-25) that encompasses a second His and Met rich domain.
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22

King, Judy A., and Robert P. Millar. "Identification of His5, Trp7, Tyr8-GnRH (chicken GnRH II) in amphibian brain." Peptides 7, no. 5 (September 1986): 827–34. http://dx.doi.org/10.1016/0196-9781(86)90102-6.

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23

Bergo, Vladislav B., Joel M. Kralj, John L. Spudich, and Kenneth J. Rothschild. "His75 in Proteorhodopsin, a Novel Component in Light-Driven Proton Translocation by Primary Pumps." Biophysical Journal 96, no. 3 (February 2009): 526a. http://dx.doi.org/10.1016/j.bpj.2008.12.2713.

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24

Blank, J., T. Kupke, E. Lowe, P. Barth, R. B. Freedman, and L. W. Ruddock. "The Influence of His94 and Pro149 in Modulating the Activity of V. cholerae DsbA." Antioxidants & Redox Signaling 5, no. 4 (August 2003): 359–66. http://dx.doi.org/10.1089/152308603768295087.

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25

Qiu, Shenshen, Dongqing Xu, Mengxue Xu, Huan Zhou, Ning Sun, Li Zhang, Mengmeng Zhao, et al. "Crystal structures of PigF, an O-methyltransferase involved in the prodigiosin synthetic pathway, reveal an induced-fit substrate-recognition mechanism." IUCrJ 9, no. 2 (March 1, 2022): 316–27. http://dx.doi.org/10.1107/s2052252521011696.

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Prodigiosin, a red linear tripyrrole pigment, is a typical secondary metabolite with numerous biological functions, such as anticancer, antibacterial and immunosuppressant activities, and is synthesized through a bifurcated biosynthesis pathway from 4-methoxy-2,2′-bipyrrole-5-carbaldehyde (MBC) and 2-methyl-3-n-amylpyrrole (MAP). The last step in the biosynthetic pathway of MBC is catalysed by PigF, which transfers a methyl group to 4-hydroxy-2,20-bipyrrole-5-carbaldehyde (HBC) to form the final product MBC. However, the catalytic mechanism of PigF is still elusive. In this study, crystal structures of apo PigF and S-adenosylhomocysteine (SAH)-bound PigF were determined. PigF forms a homodimer and each monomer consists of two domains: a C-terminal catalytic domain and an N-terminal dimerization domain. Apo PigF adopts an open conformation, while the structure of the complex with the product SAH adopts a closed conformation. The binding of SAH induces dramatic conformational changes of PigF, suggesting an induced-fit substrate-binding mechanism. Further structural comparison suggests that this induced-fit substrate-recognition mechanism may generally exist in O-methyltransferases. Docking and mutation studies identified three key residues (His98, His247 and Asp248) that are crucial for enzyme activity. The essential function of His247 and Asp248 and structure analysis suggests that both residues are involved in activation of the HBC substrate of PigF. The invariance of Asp248 in PigF further confirmed its essential role. The invariance and essential role of His98 in PigF suggests that it is involved in correctly positioning the substrate. This study provides new insight into the catalytic mechanism of PigF, reveals an induced-fit substrate-recognition model for PigF and broadens the understanding of O-methyltransferases.
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26

Tanley, Simon W. M., and John R. Helliwell. "Chemical conversion of cisplatin and carboplatin with histidine in a model protein crystallized under sodium iodide conditions." Acta Crystallographica Section F Structural Biology Communications 70, no. 9 (August 29, 2014): 1127–31. http://dx.doi.org/10.1107/s2053230x14013995.

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Cisplatin and carboplatin are platinum anticancer agents that are used to treat a variety of cancers. Previous X-ray crystallographic studies of carboplatin binding to histidine in hen egg-white lysozyme (HEWL) showed a partial chemical conversion of carboplatin to cisplatin owing to the high sodium chloride concentration used in the crystallization conditions. Also, the co-crystallization of HEWL with carboplatin in sodium bromide conditions resulted in the partial conversion of carboplatin to the transbromoplatin form, with a portion of the cyclobutanedicarboxylate (CBDC) moiety still present. The results of the co-crystallization of HEWL with cisplatin or carboplatin in sodium iodide conditions are now reported in order to determine whether the cisplatin and carboplatin converted to the iodo form, and whether this took place in a similar way to the partial conversion of carboplatin to cisplatin in NaCl conditions or to transbromoplatin in NaBr conditions as seen previously. It is reported here that a partial chemical transformation has taken place to a transplatin form for both ligands. The NaI-grown crystals belonged to the monoclinic space groupP21with two molecules in the asymmetric unit. The chemically transformed cisplatin and carboplatin bind to both His15 residues,i.e.in each asymmetric unit. The binding is only at the Nδatom of His15. A third platinum species is also seen in both conditions bound in a crevice between symmetry-related molecules. Here, the platinum is bound to three I atoms identified based on their anomalous difference electron densities and their refined occupancies, with the fourth bound atom being a Cl atom (in the cisplatin case) or a portion of the CBDC moiety (in the carboplatin case).
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27

Tsai, H., and L. A. Bobek. "Studies of the mechanism of human salivary histatin-5 candidacidal activity with histatin-5 variants and azole-sensitive and -resistant Candida species." Antimicrobial Agents and Chemotherapy 41, no. 10 (October 1997): 2224–28. http://dx.doi.org/10.1128/aac.41.10.2224.

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Histatins are a group of small, cationic, antifungal peptides present in human saliva. A previous molecular modeling analysis suggested structural similarity between the Phe14-His15 and His18-His19 dipeptide sequences in histatin-5 (Hsn-5; a 24-amino-acid polypeptide) and the sequence of miconazole (one of the azole-based antifungal therapeutic agents), implying that the mechanisms of killing of Candida albicans by these two molecules may be similar. To further elaborate on this observation, we have produced two variants of Hsn-5 in which Phe14-His15 or His18-His19 dipeptide sequences were replaced by Ala-Ala (F14A/H15A and H18A/H19A) to eliminate the phenyl and imidazole rings of the side chains and assessed their candidacidal activities against C. albicans. In addition, we tested azole-resistant C. albicans and Candida glabrata strains for their susceptibilities to Hsn-5. Analysis of the purified recombinant proteins for their candidacidal activities indicated that both variants were significantly less effective (the molar concentrations required to kill half of the maximum number of cells [ED50s], approximately 67 and approximately 149 microM for F14A/H15A and H18A/H19A, respectively) than the unaltered Hsn-5 (ED50, approximately 8 microM) at killing C. albicans, suggesting that the two dipeptide sequences are important for the candidacidal activity of Hsn-5. Assessment of the candidacidal activity of Hsn-5 with the well-characterized azole-resistant strains of C. albicans and C. glabrata, however, suggested that the mode of action of histatins against Candida is distinct from that of azole-based antifungal agents because Hsn-5 kills both azole-sensitive and azole-resistant strains equally well.
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28

KIMURA, Shigenobu, Akihiro KIKUCHI, Toshiya SENDA, Yoshitsugu SHIRO, and Masao FUKUDA. "Tolerance of the Rieske-type [2Fe-2S] cluster in recombinant ferredoxin BphA3 from Pseudomonas sp. KKS102 to histidine ligand mutations." Biochemical Journal 388, no. 3 (June 7, 2005): 869–78. http://dx.doi.org/10.1042/bj20042077.

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BphA3 from Pseudomonas sp. KKS102 is a Rieske-type [2Fe-2S] ferredoxin that transfers electrons from an NADH-dependent oxidoreductase, BphA4, to a biphenyl dioxygenase complex. A high-level expression and purification system for the recombinant BphA3 in Escherichia coli was constructed. Two histidine ligands of the Rieske-type cluster in BphA3, were each replaced with serine, cysteine, asparagine and tyrosine. The single mutants, in which either His44 or His65 was replaced with a cysteine residue (CH and HC mutants respectively), and the double mutant, in which both histidine residues were replaced with cysteine residue (CC mutant), accumulated to high levels in the E. coli cells, while the other single mutants did not. The purified WT (wild-type) protein showed characteristic near-UV and visible absorption and CD spectra of Rieske-type clusters. The X-ray absorption spectra were suggestive of the existence of [2Fe-2S] clusters, with one histidine and three cysteine ligands in the CH and HC mutants, and an [2Fe-2S] cluster with four cysteine ligands in the CC mutant. The BphA4-dependent cytochrome c reductase activities of the mutants were less than 0.3% of that of the WT protein. The redox potential of the WT protein determined by cyclic voltammetry was −180±5 mV compared with the standard hydrogen electrode, and that of the CH mutant was approx. 175 mV lower. The changes in the near-UV and visible absorption spectra of the mutants showed that the reduced iron–sulphur clusters in the mutants were unstable. His44 and His65 in BphA3 can be replaced with cysteine residues, but are required for the stabilization of the reduced form of the cluster.
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29

Wang, Chunxue, Leslie L. Lovelace, Shengfang Sun, John H. Dawson, and Lukasz Lebioda. "Structures of K42N and K42Y sperm whale myoglobins point to an inhibitory role of distal water in peroxidase activity." Acta Crystallographica Section D Biological Crystallography 70, no. 11 (October 16, 2014): 2833–39. http://dx.doi.org/10.1107/s1399004714017787.

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Sperm whale myoglobin (Mb) functions as an oxygen-storage protein, but in the ferric state it possesses a weak peroxidase activity which enables it to carry out H2O2-dependent dehalogenation reactions. Hemoglobin/dehaloperoxidase fromAmphitrite ornata(DHP) is a dual-function protein represented by two isoproteins DHP A and DHP B; its peroxidase activity is at least ten times stronger than that of Mb and plays a physiological role. The `DHP A-like' K42Y Mb mutant (K42Y) and the `DHP B-like' K42N mutant (K42N) were engineered in sperm whale Mb to mimic the extended heme environments of DHP A and DHP B, respectively. The peroxidase reaction rates increased ∼3.5-fold and ∼5.5-fold in K42Y and K42NversusMb, respectively. The crystal structures of the K42Y and K42N mutants revealed that the substitutions at position 42 slightly elongate not only the distances between the distal His55 and the heme iron but also the hydrogen-bonding distances between His55 and the Fe-coordinated water. The enhanced peroxidase activity of K42Y and K42N thus might be attributed in part to the weaker binding of the axial water molecule that competes with hydrogen peroxide for the binding site at the heme in the ferric state. This is likely to be the mechanism by which the relationship `longer distal histidine to Fe distance – better peroxidase activity', which was previously proposed for heme proteins by Matsuiet al.(1999) (J. Biol. Chem.274, 2838–2844), works. Furthermore, positive cooperativity in K42N was observed when its dehaloperoxidase activity was measured as a function of the concentration of the substrate trichlorophenol. This serendipitously engineered cooperativity was rationalized by K42N dimerization through the formation of a dityrosine bond induced by excess H2O2.
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30

Grinthal, Alison, and Guido Guidotti. "Substitution of His59 Converts CD39 Apyrase into an ADPase in a Quaternary Structure Dependent Manner†." Biochemistry 39, no. 1 (January 2000): 9–16. http://dx.doi.org/10.1021/bi991751k.

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31

Dance, Ian. "New insights into the reaction capabilities of His195 adjacent to the active site of nitrogenase." Journal of Inorganic Biochemistry 169 (April 2017): 32–43. http://dx.doi.org/10.1016/j.jinorgbio.2017.01.005.

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32

Mirzabekov, Andrei D., Dmitrii V. Pruss, and Konstantin K. Ebralidse. "Chromatin superstructure-dependent crosslinking with DNA of the histone H5 residues Thr1, His25 and His62." Journal of Molecular Biology 211, no. 2 (January 1990): 479–91. http://dx.doi.org/10.1016/0022-2836(90)90366-t.

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33

Zeidler, Waltraud, Christian Egle, Sofia Ribeiro, Annett Wagner, Vladimir Katunin, Roland Kreutzer, Marina Rodnina, Wolfgang Wintermeyer, and Mathias Sprinzl. "Site-Directed Mutagenesis of Thermus thermophilus Elongation Factor Tu. Replacement of His85, Asp81 and Arg300." European Journal of Biochemistry 229, no. 3 (May 1995): 596–604. http://dx.doi.org/10.1111/j.1432-1033.1995.tb20503.x.

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34

Verhoef, Daniël, Mark Schreuder, Ka Lei Cheung, Pieter H. Reitsma, and Mettine H. A. Bos. "Engineered Factor Xa Variants Retain Procoagulant Activity Independent of Direct Factor Xa-Inhibitors." Blood 126, no. 23 (December 3, 2015): 126. http://dx.doi.org/10.1182/blood.v126.23.126.126.

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Abstract The venom of the Australian Elapid snake Pseudonaja textilis contains a prothrombin-activating complex that consists of factor Xa (FXa) and factor Va (FVa) homologs which are evolutionary adapted to derail the hemostatic system of its prey, leading to runaway coagulation. These adaptations include functional resistance to inactivation by the main inhibitors of coagulation, antithrombin and activated protein C. Further studies revealed that venom FXa, unlike other FXa species, is also resistant to inhibition by direct oral FXa-inhibitors such as rivaroxaban and apixaban (Ki >1000 nM for venom FXa vs. 1 nM for human FXa). Accordingly, venom FXa is able to support thrombin generation (TG) in FX-depleted plasma spiked with pharmacological concentrations (0.4-2 μM) of these FXa-inhibitors. While human FXa-initiated TG resulted in a 8-fold prolonged lag time and a 70% reduced thrombin peak, those parameters were within normal range in venom FXa-triggered TG. Venom FX homologs produced by Elapid snakes comprise a heterogeneous insertion between His91-Tyr99 (chymotrypsin numbering) in the serine protease domain. A recent crystal structure of one of these homologs shows that this insertion is in close proximity of the active site pocket. In contrast, P. textilis liver-derived plasma FX, which, when activated, is fully inhibited by the FXa-inhibitors (Ki10 nM), lacks this structural feature. We investigated whether the His91-Tyr99 insertion is at the basis of the reduced sensitivity of venom FXa towards FXa-inhibitors. To do so, we constructed and stably expressed human-snake FX chimeras (FX-A, -B, -C) that incorporate His91-Tyr99 insertions from three venom FXa homologs. The chimeric FX variants were purified by successive ion-exchange and hydrophobic interaction chromatography steps, and FXa was generated following RVV-X-activation and size-exclusion chromatography. Evaluation of the kinetic parameters of prothrombin conversion in the presence of saturating amounts of FVa and anionic phospholipids revealed that the chimeric FXa variants exhibit an up to ~4-fold enhanced affinity for prothrombin (Km 0.11-0.29 μM) as compared to recombinant human FXa (rhFXa; Km 0.41 μM). The rate of prothrombin activation was 3-10-fold reduced (kcat 118-370 min-1 vs. 1243 min-1 for rhFXa), which may be indicative of a modified active site conformation. Consistent with this, the rate of chimeric FXa inhibition by antithrombin was impaired (kapp 0.12-0.95 x 103 M-1 s-1 vs. 4.07 x 103 M-1 s-1 for rhFXa). Furthermore, the variant that was most poorly inhibited by antithrombin (variant A) also exhibited the lowest catalytic rate of prothrombin conversion and vice versa (variant C). Conversely, apixaban or edoxaban inhibition of the FXa variants assembled into prothrombinase led to the highest Ki for chimeric variant C (2.3 or 0.3 µM), followed by variants B (1.4 or 0.2 µM), and A (0.2 or 0.006 µM) compared to rhFXa (0.004 or 0.0005 µM). Evaluation of the inhibition of uncomplexed FXa variants employing peptidyl substrate conversion revealed a similar decrease in sensitivity to the FXa-inhibitors (≤500-fold). These data suggest that insertion of the snake venom His91-Tyr99 regions indeed results in impaired engagement of the FXa active site pocket. We next assessed whether chimeric variant C, which is most resistant to inhibition by the direct FXa-inhibitors, is able to restore thrombin generation in a plasma system in the presence of apixaban or edoxaban. While rhFXa-triggered (5 nM) thrombin formation in FX-depleted plasma was inhibited by 2 μM apixaban, initiation with FXa-C (5 nM) resulted in normal thrombin generation parameters (peak thrombin 98%). In addition, the zymogen form of variant C also supported tissue factor-initiated (2 pM) thrombin generation in FX-depleted plasma with inhibitor concentrations up to 6 μM (apixaban) or 2 μM (edoxaban). Under these conditions, little if any thrombin was formed with rhFX present (peak thrombin 5%). We obtained similar results when performing these experiments in normal pooled plasma. Taken together, these results show that chimeric FX is able to restore hemostasis in plasma inhibited by the direct FXa-inhibitors, both in the zymogen as well as protease state. As such, these variants have the potential to serve as rescue therapeutic agents to overcome the effect of FXa-inhibitors in case of potential life-threatening bleeding events or emergency surgical interventions. Disclosures Bos: Bayer Hemophilia Awards: Research Funding.
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35

Tanley, Simon W. M., Laurina-Victoria Starkey, Lucinda Lamplough, Surasek Kaenket, and John R. Helliwell. "The binding of platinum hexahalides (Cl, Br and I) to hen egg-white lysozyme and the chemical transformation of the PtI6octahedral complex to a PtI3moiety bound to His15." Acta Crystallographica Section F Structural Biology Communications 70, no. 9 (August 29, 2014): 1132–34. http://dx.doi.org/10.1107/s2053230x14014009.

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This study examines the binding and chemical stability of the platinum hexahalides K2PtCl6, K2PtBr6and K2PtI6when soaked into pre-grown hen egg-white lysozyme (HEWL) crystals as the protein host. Direct comparison of the iodo complex with the chloro and bromo complexes shows that the iodo complex is partly chemically transformed to a square-planar PtI3complex bound to the Nδatom of His15, a chemical behaviour that is not exhibited by the chloro or bromo complexes. Each complex does, however, bind to HEWL in its octahedral form either at one site (PtI6) or at two sites (PtBr6and PtCl6). As heavy-atom derivatives of a protein, the octahedral shape of the hexahalides could be helpful in cases of difficult-to-interpret electron-density maps as they would be recognisable `objects'.
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36

Py, Béatrice, Bortoli-German Isabelle, Jacques Haiech, Marc Chippaux, and Frédéric Barras. "Cellulase EGZ of Erwinia chrysanthemi: structural organization and importance of His98 and Glu133 residues for catalysis." "Protein Engineering, Design and Selection" 4, no. 3 (1991): 325–33. http://dx.doi.org/10.1093/protein/4.3.325.

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37

Tyukhtenko, Sergiy, Karrie Chan, Rubin Jiang, Han Zhou, Richard W. Mercier, De-Ping Yang, Alexandros Makriyannis, and Jason J. Guo. "Hydrogen-Bonded His93 As a Sensitive Probe for Identifying Inhibitors of the Endocannabinoid Transport Protein FABP7." Chemical Biology & Drug Design 85, no. 5 (October 16, 2014): 534–40. http://dx.doi.org/10.1111/cbdd.12440.

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38

Xue, Yafeng, Bengt-Harald Jonsson, Anders Liljas, and Sven Lindskog. "Modification of a metal ligand in carbonic anhydrase: Crystal structure of His94 →Glu human isozyme II." FEBS Letters 352, no. 2 (September 26, 1994): 137–40. http://dx.doi.org/10.1016/0014-5793(94)00936-8.

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39

Budanov, Andrei V., Tzipora Shoshani, Alexander Faerman, Elena Zelin, Iris Kamer, Hagar Kalinski, Svetlana Gorodin, et al. "Identification of a novel stress-responsive gene Hi95 involved in regulation of cell viability." Oncogene 21, no. 39 (September 2002): 6017–31. http://dx.doi.org/10.1038/sj.onc.1205877.

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40

Sakurada, Tkukasa, Akinori Sugiyama, Koichi Tanno, Shinobu Sakurada, Masataka Ohba, and Kensuke Kisara. "Pharmacological profile of tachykinin NK1 receptor antagonist, [Tyr6, D-Trp7, D-His9] substance P." Japanese Journal of Pharmacology 67 (1995): 81. http://dx.doi.org/10.1016/s0021-5198(19)46292-6.

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41

Nishiwaki, Kiyoji, Naoyuki Hayashi, Shinji Irie, Dong-Hyo Chung, Satoshi Harashima, and Yasuji Oshima. "Structure of the yeast HIS5 gene responsive to general control of amino acid biosynthesis." Molecular and General Genetics MGG 208, no. 1-2 (June 1987): 159–67. http://dx.doi.org/10.1007/bf00330437.

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42

Mashima, Tsuyoshi, Koji Oohora, and Takashi Hayashi. "Substitution of an amino acid residue axially coordinating to the heme molecule in hexameric tyrosine-coordinated hemoprotein to enhance peroxidase activity." Journal of Porphyrins and Phthalocyanines 21, no. 12 (December 2017): 824–31. http://dx.doi.org/10.1142/s1088424617500936.

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To convert an originally tyrosine-coordinated heme to histidine-coordinated heme in hexameric tyrosine-coordinated hemoprotein, HTHP, Tyr45, a residue coordinating to the heme cofactor, and Arg25 located in the distal site are replaced with Phe45 and His25, respectively in each of the subunits of the protein. The obtained HTHP mutant (HTHP[Formula: see text] was characterized by SDS-PAGE, ESI-TOF MS, dynamic light scattering measurements and size exclusion chromatography. These analyses indicate that HTHP[Formula: see text] maintains its stable hexameric structure with the altered ligation of each of the heme cofactors. Comparison of UV-vis absorption spectra of the ferric-, ferrous-, CO- and CN-forms of HTHP[Formula: see text] with those of several well-known His-ligated hemoproteins indicates that heme is coordinated by the His25 residue. The reaction of HTHP[Formula: see text] with cumene hydroperoxide produces both cumyl alcohol and acetophenone in a 2.3:1 ratio, indicating that heterolytic O–O bond cleavage dominantly occurs to form the two-electron oxidized species known as compound I. Peroxidase activity of HTHP[Formula: see text] is found to follow Michaelis–Menten kinetics. The [Formula: see text] values of HTHP[Formula: see text] for H[Formula: see text]O[Formula: see text]-dependent oxidation of ABTS and guaiacol are 10- and 100-fold higher, respectively, than those of wild type HTHP (HTHP[Formula: see text]. The [Formula: see text]/[Formula: see text] values of HTHP[Formula: see text] for both substrates are increased 30-fold relative to that of HTHP[Formula: see text]. Moreover, HTHP[Formula: see text] is capable of promoting catalytic sulfoxidation of thioanisole with H[Formula: see text]O[Formula: see text] with a turnover number ca. 2-fold higher than that of HTHP[Formula: see text]. The present findings demonstrate that proximal His ligation to the heme is significantly effective to increase the peroxidase activity in the HTHP matrix.
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43

Plamondon, Pascale, Denis Brochu, Suzanne Thomas, Julie Fradette, Lucie Gauthier, Katy Vaillancourt, Nicole Buckley, Michel Frenette, and Christian Vadeboncoeur. "Phenotypic Consequences Resulting from a Methionine-to-Valine Substitution at Position 48 in the HPr Protein of Streptococcus salivarius." Journal of Bacteriology 181, no. 22 (November 15, 1999): 6914–21. http://dx.doi.org/10.1128/jb.181.22.6914-6921.1999.

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ABSTRACT In gram-positive bacteria, the HPr protein of the phosphoenolpyruvate:sugar phosphotransferase system (PTS) can be phosphorylated on a histidine residue at position 15 (His15) by enzyme I (EI) of the PTS and on a serine residue at position 46 (Ser46) by an ATP-dependent protein kinase (His∼P and Ser-P, respectively). We have isolated fromStreptococcus salivarius ATCC 25975, by independent selection from separate cultures, two spontaneous mutants (Ga3.78 and Ga3.14) that possess a missense mutation in ptsH (the gene encoding HPr) replacing the methionine at position 48 by a valine. The mutation did not prevent the phosphorylation of HPr at His15 by EI nor the phosphorylation at Ser46 by the ATP-dependent HPr kinase. The levels of HPr(Ser-P) in glucose-grown cells of the parental and mutant Ga3.78 were virtually the same. However, mutant cells growing on glucose produced two- to threefold less HPr(Ser-P)(His∼P) than the wild-type strain, while the levels of free HPr and HPr(His∼P) were increased 18- and 3-fold, respectively. The mutants grew as well as the wild-type strain on PTS sugars (glucose, fructose, and mannose) and on the non-PTS sugars lactose and melibiose. However, the growth rate of both mutants on galactose, also a non-PTS sugar, decreased rapidly with time. The M48V substitution had only a minor effect on the repression of α-galactosidase, β-galactosidase, and galactokinase by glucose, but this mutation abolished diauxie by rendering cells unable to prevent the catabolism of a non-PTS sugar (lactose, galactose, and melibiose) when glucose was available. The results suggested that the capacity of the wild-type cells to preferentially metabolize glucose over non-PTS sugars resulted mainly from inhibition of the catabolism of these secondary energy sources via a HPr-dependent mechanism. This mechanism was activated following glucose but not lactose metabolism, and it did not involve HPr(Ser-P) as the only regulatory molecule.
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Lin, Ying-Ju, and Suh-Chin Wu. "Histidine at Residue 99 and the Transmembrane Region of the Precursor Membrane prM Protein Are Important for the prM-E Heterodimeric Complex Formation of Japanese Encephalitis Virus." Journal of Virology 79, no. 13 (July 1, 2005): 8535–44. http://dx.doi.org/10.1128/jvi.79.13.8535-8544.2005.

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ABSTRACT The formation of the flavivirus prM-E complex is an important step for the biogenesis of immature virions, which is followed by a subsequent cleavage of prM to M protein through cellular protease to result in the production and release of mature virions. In this study, the intracellular formation of the prM-E complex of Japanese encephalitis virus was investigated by baculovirus coexpression of prM and E in trans in Sf9 insect cells as analyzed by anti-E antibody immunoprecipitation and sucrose gradient sedimentation analysis. A series of carboxyl-terminally truncated prM mutant baculoviruses was constructed to demonstrate that the truncations of the transmembrane (TM) region resulted in a reduction of the formation of the stable prM-E complex by approximately 40% for the TM1 (at residues 130 to 147 [prM130-147]) truncation and 20% for TM2 (at prM153-167) truncation. Alanine-scanning site-directed mutagenesis on the prM99-103 region indicated that the His99 residue was the critical prM binding element for stable prM-E heterodimeric complex formation. The single amino acid mutation at the His99 residue of prM abolishing the prM-E interaction was not due to reduced expression or different subcellular location of the mutant prM protein involved in prM-E interactions as characterized by pulse-chase labeling and confocal scanning microscopic analysis. Recombinant subviral particles were detected in the Sf9 cell culture supernatants by baculovirus coexpression of prM and E proteins but not with the prM H99A mutant. Sequence alignment analysis was further conducted with different groups of flaviviruses to show that the prM H99 residues are generally conserved. Our findings are the first report to characterize the minimum binding elements of the prM protein that are involved in prM-E interactions of flaviviruses. This information, concerning a molecular framework for the prM protein, is considered to elucidate the structure/function relationship of the prM-E complex synthesis and provide the proper trajectory for flavivirus assembly and maturation.
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45

PLOWMAN, JEFFREY E., LAWRENCE K. CREAMER, MICHAEL J. LIDDELL, and JENNIFER J. CROSS. "Structural features of a peptide corresponding to human κ-casein residues 84–101 by 1H-nuclear magnetic resonance spectroscopy." Journal of Dairy Research 66, no. 1 (February 1999): 53–63. http://dx.doi.org/10.1017/s0022029998003318.

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The peptide Val–Arg–Arg–Pro–Asn–Leu–His–Pro–Ser–Phe–Ile–Ala–Ile–Pro–Pro–Lys–Lys–Ile, which corresponds to residues 84–101 of human κ-casein, has been synthesized and its conformation preferences determined by 1H-nuclear magnetic resonance spectroscopy in dimethyl sulphoxide. The peptide adopted a largely extended chain conformation in solution and there was evidence for the presence of a β-turn involving residues Pro87–His90 of human κ-casein. The presence of a turn in this position would make the physiologically significant Arg85 residue of human κ-casein (which is equivalent to Arg97 in bovine κ-casein) unavailable for interaction with Asp249of bovine chymosin, and may partly explain why human κ-casein is hydrolysed more slowly than its bovine counterpart by bovine chymosin.
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46

López de Maturana, Rakel, Adam J. Pawson, Zhi-Liang Lu, Lindsay Davidson, Stuart Maudsley, Kevin Morgan, Simon P. Langdon, and Robert P. Millar. "Gonadotropin-Releasing Hormone Analog Structural Determinants of Selectivity for Inhibition of Cell Growth: Support for the Concept of Ligand-Induced Selective Signaling." Molecular Endocrinology 22, no. 7 (July 1, 2008): 1711–22. http://dx.doi.org/10.1210/me.2006-0537.

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Abstract GnRH and its receptor are expressed in human reproductive tract cancers, and direct antiproliferative effects of GnRH analogs have been demonstrated in cancer cell lines. The intracellular signaling responsible for this effect differs from that mediating pituitary gonadotropin secretion. The GnRH structure-activity relationship is different for the two effects. Here we report a structure-activity relationship study of GnRH agonist antiproliferative action in model cell systems of rat and human GnRH receptors stably expressed in HEK293 cells. GnRH II was more potent than GnRH I in inhibiting cell growth in the cell lines. In contrast, GnRH I was more potent than GnRH II in stimulating inositol phosphate production, the signaling pathway in gonadotropes. The different residues in GnRH II (His5, Trp7, Tyr8) were introduced singly or in pairs into GnRH I. Tyr5 replacement by His5 produced the highest increase in the antiproliferative potency of GnRH I. Tyr8 substitution of Arg8 produced the most selective analog, with very poor inositol phosphate generation but high antiproliferative potency. In nude mice bearing tumors of the HEK293 cell line, GnRH II and an antagonist administration was ineffective in inhibiting tumor growth, but d-amino acid stabilized analogs (d-Lys6 and d-Arg6) ablated tumor growth. Docking of GnRH I and GnRH II to the human GnRH receptor molecular model revealed that Arg8 of GnRH I makes contact with Asp302, whereas Tyr8 of GnRH II appears to make different contacts, suggesting these residues stabilize different receptor conformations mediating differential intracellular signaling and effects on gonadotropin and cell growth. These findings provide the basis for the development of selective GnRH analog cancer therapeutics that directly target tumor cells or inhibit pituitary gonadotropins or do both.
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47

Schmölzer, Katharina, Manuel Eibinger, and Bernd Nidetzky. "Active-Site His85 ofPasteurella dagmatisSialyltransferase Facilitates Productive Sialyl Transfer and So Prevents Futile Hydrolysis of CMP-Neu5Ac." ChemBioChem 18, no. 15 (June 21, 2017): 1544–50. http://dx.doi.org/10.1002/cbic.201700113.

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48

Lam, Y. W., W. Ammerlaan, W. S. O, F. Kroese, and D. Opstelten. "Cell Type- and Differentiation Stage-Dependent Expression of PML Domains in Rat, Detected by Monoclonal Antibody HIS55." Experimental Cell Research 221, no. 2 (December 1995): 344–56. http://dx.doi.org/10.1006/excr.1995.1384.

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49

Kim, Jang Hoon, Sunggun Lee, Saerom Park, Ji Soo Park, Young Ho Kim, and Seo Young Yang. "Slow-Binding Inhibition of Tyrosinase by Ecklonia cava Phlorotannins." Marine Drugs 17, no. 6 (June 16, 2019): 359. http://dx.doi.org/10.3390/md17060359.

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Tyrosinase inhibitors improve skin whitening by inhibiting the formation of melanin precursors in the skin. The inhibitory activity of seven phlorotannins (1–7), triphlorethol A (1), eckol (2), 2-phloroeckol (3), phlorofucofuroeckol A (4), 2-O-(2,4,6-trihydroxyphenyl)-6,6′-bieckol (5), 6,8′-bieckol (6), and 8,8′-bieckol (7), from Ecklonia cava was tested against tyrosinase, which converts tyrosine into dihydroxyphenylalanine. Compounds 3 and 5 had IC50 values of 7.0 ± 0.2 and 8.8 ± 0.1 μM, respectively, in competitive mode, with Ki values of 8.2 ± 1.1 and 5.8 ± 0.8 μM. Both compounds showed the characteristics of slow-binding inhibitors over the time course of the enzyme reaction. Compound 3 had a single-step binding mechanism and compound 5 a two-step-binding mechanism. With stable AutoDock scores of −6.59 and −6.68 kcal/mol, respectively, compounds 3 and 5 both interacted with His85 and Asn260 at the active site.
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Krishnamoorthi, Ramaswamy, Chan Lan Sun Lin, Yu Xi Gong, David VanderVelde, and Karl Hahn. "Proton NMR studies of Cucurbita maxima trypsin inhibitors: evidence for pH-dependent conformational change and His25-Tyr27 interaction." Biochemistry 31, no. 3 (January 28, 1992): 905–10. http://dx.doi.org/10.1021/bi00118a037.

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