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Journal articles on the topic 'Seco acids'

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Author: Grafiati

Published: 4 June 2021

Last updated: 20 February 2023

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1

Szoka, Łukasz, Valery Isidorov, Jolanta Nazaruk, Marcin Stocki, and Leszek Siergiejczyk. "Cytotoxicity of Triterpene Seco-Acids from Betula pubescens Buds." Molecules 24, no. 22 (November 9, 2019): 4060. http://dx.doi.org/10.3390/molecules24224060.

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The present study investigated the magnitude and mechanism of the cytotoxic effect on selected cancer cell lines of 3,4-seco-urs-4(23),20(30)-dien-3-oic acid (1), 3,4-seco-olean-4(24)-en-19-oxo-3-oic acid (2), and 3,4-seco-urs-4(23),20(30)-dien-19-ol-3-oic acid (3) isolated from downy birch (Betula pubescens) buds by carbon dioxide supercritical fluid extraction and gradient column chromatography. Cell viability in six human cancer lines exposed to these compounds was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis was quantified by annexin V/propidium iodide staining of gastric cancer AGS and colorectal cancer DLD-1 cells. To evaluate the mechanism of apoptosis, the expression of apoptosis-related proteins was analyzed by Western blot. Compound 1 exhibited non-specific toxicity, while compounds 2 and 3 were specifically toxic to colon and stomach cancer cells. The toxicity of compounds 2 and 3 against these two cell lines was greater than for compound 1. Cleavage of caspase-8, -9, and -3 was found in AGS and DLD-1 cells treated with all three seco-acids, indicating the induction of apoptosis via extrinsic and intrinsic pathways. Therefore, triterpene seco-acids (1–3) decreased cell viability by apoptosis induction. AGS and DLD-1 cells were more susceptible to seco-acids with an oxidized C19 than normal fibroblasts. Hence, it made them a new group of triterpenes with potential anticancer activity.

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2

Ma, Bin, Yan-Ping Shi, and Zhong-Jian Jia. "A-seco-Oleane-Type Triterpene Acids fromLigularia intermedia." Planta Medica 63, no. 06 (December 1997): 573–74. http://dx.doi.org/10.1055/s-2006-957773.

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3

de Léséleuc, Mylène, and Shawn K. Collins. "Direct Macrolactonization of Seco Acids via Hafnium(IV) Catalysis." ACS Catalysis 5, no. 3 (February 2, 2015): 1462–67. http://dx.doi.org/10.1021/acscatal.5b00082.

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4

Katoh, Tadashi, Noel Sayar, and Koichi Narita. "Facile Total Synthesis of Thailandepsins D–F: Novel Bicyclic Depsipeptide Histone Deacetylase Inhibitors Isolated from a Microorganism." Synthesis 51, no. 06 (February 1, 2019): 1419–26. http://dx.doi.org/10.1055/s-0037-1611707.

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The naturally occurring bicyclic depsipeptide histone deacetylase inhibitors thailandepsins D–F were efficiently synthesized for the first time in 49–61% overall yield over five steps, starting from known amine and carboxylic acid segments. The synthesis includes the condensation of the two known starting materials to directly assemble the corresponding seco-acids, which are the key precursors for macrolactonization. The seco-acids are then macrolactonized using the Shiina method to construct the requisite 15-member macrocycles.

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5

Ainge, Simon W., and Pierre Vogel. "Total asymmetric synthesis of seco-acids of 9,12-anhydroerythronolide aglycons." Tetrahedron Letters 39, no. 23 (June 1998): 4039–42. http://dx.doi.org/10.1016/s0040-4039(98)00691-1.

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6

ZORINA, A. D., YU D. MIKHAILOV, L. V. BALYKINA, I. I. SMIRNOV, V. G. PLATONOV, M. A. GORDON, N. P. CHIZHOV, and A. G. SHAVVA. "ChemInform Abstract: Synthesis of Seco-Acids of the Dammarane Series." ChemInform 28, no. 46 (August 3, 2010): no. http://dx.doi.org/10.1002/chin.199746193.

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7

Parsons, Ian C., Alexander I. Gray, Peter G. Waterman, Catherine Lavaud, and Georges Massiot. "Seco ring-A triterpene acids from the resin of Dacryodes normandii." Phytochemistry 30, no. 4 (January 1991): 1221–23. http://dx.doi.org/10.1016/s0031-9422(00)95205-1.

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8

Patel, Dinesh V., and Eric M. Gordon. "C-2 desmethyl seco-mevinic acids. Monocyclic HMG-CoA reductase inbibitors." Bioorganic & Medicinal Chemistry Letters 1, no. 10 (January 1991): 509–12. http://dx.doi.org/10.1016/s0960-894x(01)80455-8.

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9

Klinotová, Eva, Helena Pavlíková, Martina Pressová, Hana Chodounská, Jiří Klinot, Jiří Protiva, and Alois Vystrčil. "E-seco-Acids of pentacyclic triterpenoids. Oxidative cleavage of ring E in 3β-acetoxy-21-oxo-18α,19βH-ursan-28→20β-olide." Collection of Czechoslovak Chemical Communications 52, no. 11 (1987): 2744–52. http://dx.doi.org/10.1135/cccc19872744.

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Oxidative cleavage of 3β-acetoxy-22-hydroxymethylene-21-oxo-18α,19βH-ursan-28→20β-olide (VII) and 3β-acetoxy-21,22-dioxo-18α,19βH-ursan-28→20β-olide (VIII) afforded primarily the E-seco-acid XII which was converted into acids XVI and XX, isomeric at the C(17) carbon atom. Configuration of these acids has been determined.

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10

AINGE, S. W., and P. VOGEL. "ChemInform Abstract: Total Asymmetric Synthesis of seco-Acids of 9,12-Anhydroerythronolide Aglycons." ChemInform 29, no. 34 (June 20, 2010): no. http://dx.doi.org/10.1002/chin.199834282.

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11

Happi, Gervais Mouthé, Ferdinand Mouafo Talontsi, Hartmut Laatsch, Sebastian Zühlke, Bonaventure Tchaleu Ngadjui, Michael Spiteller, and Simeon Fogue Kouam. "seco -Tiaminic acids B and C: Identification of two novel 3,4- seco -tirucallane triterpenoids isolated from the root of Entandrophragma congoënse (Meliaceae)." Fitoterapia 124 (January 2018): 17–22. http://dx.doi.org/10.1016/j.fitote.2017.10.004.

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12

Leppik, R. A., and D. J. Sinden. "Pseudomonas μtant strains that accumulate androstane and seco-androstane intermediates from bile acids." Biochemical Journal 243, no. 1 (April 1, 1987): 15–21. http://dx.doi.org/10.1042/bj2430015.

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Transposon mutant strains which were affected in bile acid catabolism were isolated from four Pseudomonas spp. Two of the mutant groups isolated were found to accumulate 12 alpha-hydroxyandrosta-1,4-diene-3,17-dione as the major product from deoxycholic acid. Strains in one of these two groups were able to grow on steroids such as chenodeoxycholic acid, which lacks a 12 alpha-hydroxy function, whereas the one member of the second group could not. With chenodeoxycholic acid, this latter strain accumulated a yellow muconic-like derivative, tentatively identified as 3,7-dihydroxy-5,9,17-trioxo-4(5),9(10)-disecoandrosta-1(10)2 -dien-4-oic acid. Members of two further mutant groups accumulated either 12 beta-hydroxyandrosta-1,4-diene-3,17-dione or 3,12 beta-dihydroxy-9(10)-secoandrosta-1,3,5(10)-triene-9,17-dione as the major product from deoxycholic acid. The relationship between the catabolism of m- and p-cresol, 3-ethylphenol and the bile acids was also examined.

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13

Wang, Hongmin, Ruonan Ning, Yu Shen, Zhenhua Chen, Jinlong Li, Rujun Zhang, Ying Leng, and Weimin Zhao. "Lithocarpic Acids A–N, 3,4-seco-Cycloartane Derivatives from the Cupules of Lithocarpus polystachyus." Journal of Natural Products 77, no. 8 (August 6, 2014): 1910–20. http://dx.doi.org/10.1021/np500379f.

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14

Baas, Wim J., and Ivonne E. M. Van Berkel. "3,4-Seco-triterpenoid acids and other constituents of the leaf wax of Hoya naumanii." Phytochemistry 30, no. 5 (January 1991): 1625–28. http://dx.doi.org/10.1016/0031-9422(91)84221-d.

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15

Kazakova, Oxana, Irina Smirnova, Elena Tret’yakova, René Csuk, Sophie Hoenke, and Lucie Fischer. "Cytotoxic Potential of a-Azepano- and 3-Amino-3,4-SeCo-Triterpenoids." International Journal of Molecular Sciences 22, no. 4 (February 8, 2021): 1714. http://dx.doi.org/10.3390/ijms22041714.

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Semi-synthetic triterpenoids, holding an amino substituted seven-membered A-ring (azepano-ring), which could be synthesized from triterpenic oximes through a Beckmann type rearrangement followed by a reduction of lactame fragment, are considered to be novel promising agents exhibiting anti-microbial, alpha-glucosidase, and butyrylcholinesterase inhibitory activities. In this study, in an attempt to develop new antitumor candidates, a series of A-ring azepano- and 3-amino-3,4-seco-derivatives of betulin, oleanolic, ursolic, and glycyrrhetinic acids were evaluated for their cytotoxic activity against five human cancer cell lines and non-malignant mouse fibroblasts by means of a colorimetric sulforhodamine assay. Azepanoallobetulinic acid amide derivative 11 was the most cytotoxic compound of this series but showed little selectivity between the different human tumor cell lines. Flow cytometry experiments showed compound 11 to act mainly by apoptosis (44.3%) and late apoptosis (21.4%). The compounds were further screened at the National Cancer Institute towards a panel of 60 cancer cell lines. It was found that compounds 3, 4, 7, 8, 9, 11, 15, 16, 19, and 20 showed growth inhibitory (GI50) against the most sensitive cell lines at submicromolar concentrations (0.20–0.94 μM), and their cytotoxic activity (LC50) was also high (1–6 μM). Derivatives 3, 8, 11, 15, and 16 demonstrated a certain selectivity profile at GI50 level from 5.16 to 9.56 towards K-562, CCRF-CEM, HL-60(TB), and RPMI-8226 (Leukemia), HT29 (Colon cancer), and OVCAR-4 (Ovarian cancer) cell lines. Selectivity indexes of azepanoerythrodiol 3 at TGI level ranged from 5.93 (CNS cancer cell lines SF-539, SNB-19 and SNB-75) to 14.89 for HCT-116 (colon cancer) with SI 9.56 at GI50 level for the leukemia cell line K-562. The present study highlighted the importance of A-azepano-ring in the triterpenic core for the development of novel antitumor agents, and a future aim to increase the selectivity profile will thus lie in the area of modifications of azepano-triterpenic acids at their carboxyl group.

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16

Krajčová, A., V. Schulzová, J. Hajšlová, and M. Bjelková. "Lignans in Flaxseed." Czech Journal of Food Sciences 27, Special Issue 1 (June 24, 2009): S252—S255. http://dx.doi.org/10.17221/1062-cjfs.

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Lignans are phytoestrogens which are present in a wide variety of plants. Epidemiological studies indicate that phytoestrogen-rich diets reduce risk of various hormone-dependent cancers, heart disease, and osteroporosis. One of the reachest dietary sources of lignans are flaxseeds, with glycosides of secoisolariciresinol (SECO) and matairesinol (MAT) as the major components. In this study LC-MS/MS method for the determination of plant lignans SECO and MAT in flaxseed was developed for analysis of a wide range of samples: (<I>I</I>) nine cultivars of oil flax treated with two types of fertilisers containing humic acids and <I>(ii</I>) fibre flax cultivar Venica fertilized with preparations containing various amounts of zinc. The levels of major phytoestrogen, SECO, were in range 2312–6994 mg/kg in oil flax and 1570–3100 mg/kg in fibre flax. The content of MAT was significantly lower, ranging from 3 to 9 in oil flax and 7–27 mg/kg in fibre flax.

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17

Wang, Jian-Xin, and Tong-Shuang Li. "The Retro-Michael Reaction of 1,5-Dicarbonyl Compounds: Scope and Limitation." Collection of Czechoslovak Chemical Communications 64, no. 1 (1999): 107–13. http://dx.doi.org/10.1135/cccc19990107.

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Under catalysis of NaOH or KOH adsorbed on glass wool and by using steam distillation, (20R,S)-4,4,5,14-tetramethyl-18,19-dinor-13,17-seco-5β,8α,9β,10α,14β-cholestane-13,17-dione (1) and 3,14-dioxo-14,15-seco-5α-cholestan-15-al (4) gave good yield (>59%) of the corresponding tricyclic compounds (8a, 8b and 10a) via a retro-Michael reaction at 250 °C. While 5-oxo-4-nor-3,5-secocholestan-3-oic acid (6) and ethyl 5-oxo-4-nor-3,5-secocholestan-3-oate (7) afforded low yield (<15%) of the retro-Michael cleavage products (12a, 12b) at the same conditions. Thus, the retro-Michael reaction worked well for 1,5-diketones and 1,5-keto aldehydes but gave poor yield for 1,5-keto esters and 1,5-keto acids.

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18

Yakovleva, M. P., K. S. Denisova, V. A. Vydrina, A. G. Tolstikov, and G. Yu Ishmuratov. "Methods for Macrolactonization of Seco Acids in the Synthesis of Natural and Biologically Active Compounds." Russian Journal of Organic Chemistry 57, no. 5 (May 2021): 679–729. http://dx.doi.org/10.1134/s1070428021050018.

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19

Fraga, Braulio M., Pedro González, Melchor G. Hernández, and Sergio Suárez. "Formation of 2,3-seco-acids in the biotransformation of the diterpene ribenone by Gibberella fujikuroi." Tetrahedron 55, no. 6 (February 1999): 1781–92. http://dx.doi.org/10.1016/s0040-4020(98)01190-9.

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20

Chen, Ting, La Hua, Guixin Chou, Xudong Mao, and Xianliang Zou. "A Unique Naphthone Derivative and a Rare 4,5-seco-Lanostane Triterpenoid from Poria cocos." Molecules 23, no. 10 (September 30, 2018): 2508. http://dx.doi.org/10.3390/molecules23102508.

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A previously undescribed naphthalenone derivative, sohiracillinone (1), and a novel 4,5-seco-lanostane triterpenoid, 11β-ethoxydaedaleanic acid A (2) were isolated with two new lanostane triterpenoids, ceanphytamic acids A (3) and B (4), from the EtOH extract of Poria cocos along with 17 known compounds 5–21. The absolute configuration of sohiracillinone (1) was unambiguously identified by NMR and electronic circular dichroism (ECD) data. The structures of other new compounds were elucidated on the basis of NMR and mass spectroscopy (MS), and the cytotoxic activities of all the isolated components were evaluated.

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21

Blanco, Juan, Gonzalo Álvarez, José Rengel, Rosario Díaz, Carmen Mariño, Helena Martín, and Eduardo Uribe. "Accumulation and Biotransformation of Dinophysis Toxins by the Surf Clam Mesodesma donacium." Toxins 10, no. 8 (August 4, 2018): 314. http://dx.doi.org/10.3390/toxins10080314.

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Surf clams, Mesodesma donacium, were shown to accumulate toxins from Dinophysis acuminata blooms. Only pectenotoxin 2 (PTX2) and some of its derivatives were found, and no toxins from the okadaic acid group were detected. PTX2 seems to be transformed to PTX2 seco-acid (PTX2sa), which was found in concentrations more than ten-fold those of PTX2. The seco-acid was transformed to acyl-derivatives by esterification with different fatty acids. The estimated amount of these derivatives in the mollusks was much higher than that of PTX2. Most esters were originated by even carbon chain fatty acids, but some originated by odd carbon number were also found in noticeable concentrations. Some peaks of toxin in the bivalves did not coincide with those of Dinophysis abundance, suggesting that there were large differences in toxin content per cell among the populations that developed throughout the year. The observed depuration (from the digestive gland) was fast (more than 0.2 day−1), and was faster for PTX2 than for PTX2sa, which in turn was faster than that of esters of PTX2sa. PTX2 and PTX2sa were distributed nearly equally between the digestive gland and the remaining tissues, but less than 5% of the palmytoyl-esters were found outside the digestive gland.

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22

Martin, Stephen F., Wen-Cherng Lee, Gregory J. Pacofsky, Ricky P. Gist, and Thomas A. Mulhern. "Strategies for Macrolide Synthesis. A Concise Approach to Protected Seco-Acids of Erythronolides A and B." Journal of the American Chemical Society 116, no. 11 (June 1994): 4674–88. http://dx.doi.org/10.1021/ja00090a016.

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23

Vedernikov, D. N., and V. I. Roshchin. "Extractive compounds of betulaceae family birch buds (Betula pendula Roth.): V. Composition of triterpene seco-acids." Russian Journal of Bioorganic Chemistry 38, no. 7 (November 30, 2012): 762–68. http://dx.doi.org/10.1134/s1068162012070229.

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24

Patel, Dinesh V., Robert J. Schmidt, and Eric M. Gordon. "C-2 dimethyl seco-mevinic acids. Synthesis of monocyclic HMG-CoA reductase inhibitors from (R)-(-)-carvone." Journal of Organic Chemistry 57, no. 26 (December 1992): 7143–51. http://dx.doi.org/10.1021/jo00052a031.

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25

Sejbal, Jan, Jiří Klinot, Daniela Hrnčířová, and Alois Vystrčil. "Oxidation of 19β,28-epoxy-18α-oleanan-3-one and -1-one with peracids." Collection of Czechoslovak Chemical Communications 50, no. 12 (1985): 2753–59. http://dx.doi.org/10.1135/cccc19852753.

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The reaction of 3-oxo derivative I and 1-oxo derivative XII of 19β,28-epoxy-18α-oleanane with peracids leads to corresponding lactones II or XIII, respectively, which were converted to A-seco acids III, V, and XIV and esters IV, VI, VII, and XV. Under acid catalysis oxidation of ketone I results in the degradation of one methyl group in position 4 and formation of compounds VIII and IX. On reaction with 3-chloroperbenzoic acid the α,β-unsaturated ketone XVI gives epoxyketone XVII.

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26

Klinotová, Eva, Martin Rejzek, Hana Zůnová, Jan Sejbal, Jiří Klinot, and Jiří Urban. "Oxidation of 3β,28-Diacetoxy-18-lupen-21-one with Peroxy Acids: A Way to Des-E-lupane Derivatives." Collection of Czechoslovak Chemical Communications 58, no. 10 (1993): 2505–16. http://dx.doi.org/10.1135/cccc19932505.

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Oxidation of 3β,28-diacetoxy-18-lupen-21-one (I) and its 18β, 19β-epoxy derivative III with peracetic acid, catalyzed with strong acids, proceeds with cleavage of the bond between C-19 and C-21 under formation of E-seco derivatives with hydroxyl and isobutyryl groups on C-18 (spiro lactones V - VII and acid VIII). Oxidative removal of the isobutyryl fragment in spiro lactone VI by treatment with lead tetraacetate leads to the tetranor derivative - keto lactone XI which in an alkaline medium loses formaldehyde from C-17 to give des-E acid XVI.

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27

MARTIN, S. F., W. C. LEE, G. J. PACOFSKY, R. P. GIST, and T. A. MULHERN. "ChemInform Abstract: Strategies for Macrolide Synthesis. A Concise Approach to Protected Seco-Acids of Erythronolides A and B." ChemInform 25, no. 46 (August 18, 2010): no. http://dx.doi.org/10.1002/chin.199446257.

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28

Solladié, Guy, and Christine Gerber. "Asymmetric Synthesis of the Seco-Acids of (R,R)-Pyrenophorin and (R)-Patulolide A Monitored by a Chiral Sulfoxide Group." Synlett 1992, no. 05 (1992): 449–50. http://dx.doi.org/10.1055/s-1992-21377.

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29

Lamphear, James G., Gregory A. Bohach, and Robert R. Rich. "Structural Dichotomy of Staphylococcal Enterotoxin C Superantigens Leading to MHC Class II-Independent Activation of T Lymphocytes." Journal of Immunology 160, no. 5 (March 1, 1998): 2107–14. http://dx.doi.org/10.4049/jimmunol.160.5.2107.

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Abstract We have recently characterized an MHC class II-deficient human cell line, SW480, that supports the proliferation of purified human T cells in the presence of the staphylococcal enterotoxin and superantigen SEC1, but not the closely related isotypes SEC2 or SEC3. We now investigate the structural basis of this dichotomy and explore possible mechanisms that may account for it. Differences in activity between SEC1 and SEC2 were not attributable to differences in biochemical modification, to differences in Vβ specificity, or to the potential to induce anergy. SEC2 inhibited SEC1-mediated T cell activation in the presence of SW480 cells, suggesting that SEC2 could compete with SEC1 for binding to the TCR but was unable to productively signal through the TCR. Utilizing a panel of hybrid enterotoxins we identified specific amino acids near the NH2-terminus of SEC1 that abrogated MHC class II-independent T cell activation, yet did not alter potency in the presence of class II+ APC. These residues mapped to the putative TCR binding domain of SEC1, and suggest that subtle differences in TCR binding affinity or the topology of the SEC1-TCR interaction can compensate for the lack of MHC class II and hence promote T cell proliferation.

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30

Liu, Weilong, Zhimei Yu, and Nicolas Winssinger. "Total Syntheses of Paraconic Acids and 1,10-seco-Guaianolides via a Barbier Allylation/Translactonization Cascade of 3-(Bromomethyl)-2(5H)-furanone." Organic Letters 23, no. 3 (January 27, 2021): 969–73. http://dx.doi.org/10.1021/acs.orglett.0c04165.

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31

Nair, J., H. Müller, M. Peterson, and P. Novick. "Sec2 protein contains a coiled-coil domain essential for vesicular transport and a dispensable carboxy terminal domain." Journal of Cell Biology 110, no. 6 (June 1, 1990): 1897–909. http://dx.doi.org/10.1083/jcb.110.6.1897.

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SEC2 function is required at the post-Golgi apparatus stage of the yeast secretory pathway. The SEC2 sequence encodes a protein product of 759 amino acids containing an amino terminal region that is predicted to be in an alpha-helical, coiled-coil conformation. Two temperature-sensitive alleles, sec2-41 and sec2-59, encode proteins truncated by opal stop codons and are suppressible by an opal tRNA suppressor. Deletion analysis indicates that removal of the carboxyl terminal 251 amino acids has no apparent phenotype, while truncation of 368 amino acids causes temperature sensitivity. The amino terminal half of the protein, containing the putative coiled-coil domain, is essential at all temperatures. Sec2 protein is found predominantly in the soluble fraction and displays a native molecular mass of greater than 500 kD. All phenotypes of the temperature-sensitive sec2 alleles are partially suppressed by duplication of the SEC4 gene, but the lethality of a sec2 disruption is not suppressed. The sec2-41 mutation exhibits synthetic lethality with the same subset of the late acting sec mutants as does sec4-8 and sec15-1. The Sec2 protein may function in conjunction with the Sec4 and Sec15 proteins to control vesicular traffic.

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32

Smirnova, Irina E., and Oxana B. Kazakova. "Structure – Anti-influenza Type a Activity Relationship among a Series of Nitrogen Lupane Triterpenoids." Natural Product Communications 13, no. 10 (October 2018): 1934578X1801301. http://dx.doi.org/10.1177/1934578x1801301008.

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Fifty-one derivatives of lupeol, betulin, betulonic and acanthochlamic acids modified at C3, C20 and C28 of the lupane core including four new ones (37, 49 –51) and forty-seven previously synthesized derivatives (1 – 36, 36 – 48) were screened for their in vitro anti-influenza type A (H1N1, H3N2 and H5N1) activity at the NIAID. The selectivity index (SI) against Flu A for tested triterpenoids ranged from > 20 to 0. Betulonic acid 2-aminopyridinylamide was a leader being active against H1N1, H3N2 and H5N1 with SI > 20, 1.8 and 5.3, respectively. The betulonic acid methoxy- and nitro-substituted benzalhydrazides showed selectivity only against H5N1, while lupeol and 3-oximino-betulonic acid benzalhydrazides were active against three types of Flu A. A-seco-aminoderivatives were more effective than the initial acanthochlamic acid against H1N1, but practically inactive against H3N2, with bis- N-methylpiperazinylamide as a leader in this series. Triterpenoids with a long-chain substituent at C17 containing amide or hydrazide bonds with aromatic or heterocyclic fragments exert positive influence on the activity.

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33

Isidorov, Valery A., Jolanta Nazaruk, Marcin Stocki, and Sławomir Bakier. "Secondary metabolites of downy birch buds (Betula pubescens Erch.)." Zeitschrift für Naturforschung C 77, no. 3-4 (October 20, 2021): 145–55. http://dx.doi.org/10.1515/znc-2021-0036.

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Abstract The subject of this study is the composition of low-molecular-weight metabolites in downy birch (Betula pubescens) buds and their participation in protection from various kinds of stress. Using the GC-MS, 640 compounds were detected, of which 314 were identified in downy birch buds for the first time. The volatile components detected using the SPME technique mainly consisted (about 70% of the total ionic current of the chromatogram, TIC) of mixtures of sesquiterpenoids. The exudate covering the buds, along with sesquiterpenoids (approximately 60% of TIC), included flavonoids (25% of TIC). The main part of the material extracted by supercritical carbon dioxide from buds comprised sesquiterpenoids and triterpenoids (47 and 28% of TIC, respectively). Via column chromatography, 25 known compounds (mainly flavonoids and triterpenoids) were isolated, most of which were first discovered in the buds of downy birch. Many compounds of these classes have strong biological activity and probably either directly or indirectly perform a protective function in birch buds. An assumption is made about the biological role of a number of secondary metabolites (such as volatile isomeric megastigmatriens and triterpene seco-acids) as well as about these compounds’ possible means of biosynthesis, which were first discovered in the buds of downy birch.

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34

Diao, Liuyang, Qilei Dong, Zhaohui Xu, Sheng Yang, Jiahai Zhou, and Roland Freudl. "Functional Implementation of the Posttranslational SecB-SecA Protein-Targeting Pathway in Bacillus subtilis." Applied and Environmental Microbiology 78, no. 3 (November 23, 2011): 651–59. http://dx.doi.org/10.1128/aem.07209-11.

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ABSTRACTBacillus subtilisand its close relatives are widely used in industry for the Sec-dependent secretory production of proteins. Like other Gram-positive bacteria,B. subtilisdoes not possess SecB, a dedicated targeting chaperone that posttranslationally delivers exported proteins to the SecA component of the translocase. In the present study, we have implemented a functional SecB-dependent protein-targeting pathway intoB. subtilisby coexpressing SecB fromEscherichia colitogether with a SecA hybrid protein in which the carboxyl-terminal 32 amino acids of theB. subtilisSecA were replaced by the corresponding part of SecA fromE. coli.In vitropulldown experiments showed that, in contrast toB. subtilisSecA, the hybrid SecA protein gained the ability to efficiently bind toE. coliSecB, suggesting that the structural details of the extreme C-terminal region of SecA constitute a crucial SecB binding specificity determinant. Using a poorly exported mutant maltose binding protein (MalE11) and alkaline phosphatase (PhoA) as model proteins, we could demonstrate that the secretion of both proteins byB. subtiliswas significantly enhanced in the presence of the artificial protein targeting pathway. Mutations in SecB that do not influence its chaperone activity but prevent its interaction with SecA abolished the secretion stimulation of both proteins, demonstrating that the implemented pathway in fact critically depends on the SecB targeting function. From a biotechnological view, our results open up a new strategy for the improvement of Gram-positive bacterial host systems for the secretory production of heterologous proteins.

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Ayerza (h), Ricardo. "Variaciones en el contenido de proteína, lípidos y ácidos grasos de la semilla de chía (Salvia hispanica L.) producida comercialmente en Ecuador." La Técnica: Revista de las Agrociencias. ISSN 2477-8982, no. 22 (December 18, 2019): 11. http://dx.doi.org/10.33936/la_tecnica.v0i22.1785.

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Variations in the protein, lipid and fatty acid content of the commercial chia seed (Salvia hispánica L.) produced in Ecuador Resumen El objetivo fue determinar las variaciones en los contenidos de proteína, lípidos y composición de ácidos grasos de las semillas de chía producidas comercialmente en seis sitios de los ecosistemas de los Valles Interandinos (Altos y Bajos), Selva Lluviosa Pluviestacional y Bosque Seco Tropical, del Ecuador. El contenido de proteína fue más alto (p<0,05) en las semillas de Bosque de Oro (24,78%) y El Azúcar (24,35%) que las de los otros cuatro sitios, y sin diferencias significativas (P<0,05) entre ellos. Las semillas de Bosque de Oro (34,90%) y San Pablo presentaron el más alto contenido de lípidos, aunque sin diferencias significativas (p<0,05) con las de Salinas (32,65%) y Patate (31.97%). Las semillas originadas en Salinas presentaron el mayor (p<0,05) contenido de α-linolénico (66,75%), seguido por las de Patate (63,93%), Guayllabamba (63,57%), Bosque de Oro (63,53%) y San Pablo (62,70%). El ácido graso α-linolénico presentó una alta relación negativa con los ácidos grasos palmítico (R2 = 0,797; p<0,001), linoleico (R2 = 0,862; p<0,001), y oleico (R2 = 0,767; p<0,001). Palabras clave: aceite; ácidos grasos; chía; Ecuador; Salvia hispánica L. Abstract The objective was to determine the variations in the protein content, lipids and fatty acids composition of the chia seeds commercially produced in six locations of the Inter-Andean Valley (Low and high), Rainforest and Tropical Dry Forest ecosystems of Ecuador. The protein content was higher (p< 0.05) in the seeds from Bosque de Oro (24.78%) and El Azúcar (24.35%) than those originated in the other four locations and without significant differences (p < 0.05) between them. The seeds of Bosque de Oro (34.90%) and San Pablo had the highest lipid content, although without significant differences (p<0.05) with those of Salinas (32.65%) and Patate (31.97%). The seeds originated in Salinas had the highest (p<0.05) content of α-linolenic (66.75%), followed by those of Patate (63.93%), Guayllabamba (63.57%), Bosque de Oro (63.53%) and San Pablo (62.70%). The α-linolenic fatty acid showed a high negative relationship with palmitic fatty acids (R2 = 0.797; p<0,001), linoleic (R2 = 0.862; p<0.001), and oleic (R2 = 0.767; p<0.001). Keywords: chia; Ecuador; fatty acids; oil; Salvia hispanica L.

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Coelho, Christian, Cécile Bord, Karine Fayolle, Cindy Bibang, and Stéphanie Flahaut. "Development of a Novel Flavored Goat Cheese with Gentiana lutea Rhizomes." Foods 12, no. 3 (January 19, 2023): 468. http://dx.doi.org/10.3390/foods12030468.

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Gentiana lutea rhizomes, generally used as a bittering agent in food, were harvested from two geographical sites (Massif Central: MC and Jura: J) to evaluate their potential use in the flavoring step during goat cheesemaking. Gentian flavored goat cheeses (MCGC and JGC) were elaborated by a one-night immersion of unflavored goat cheeses (CGC) into gentian-infused whey. The impregnation of gentian in goat cheeses was evaluated by chemical and sensory analysis. The chemical composition of cheeses was analyzed by HS-SPME-GC-MS (Head-Space—Solid Phase MicroExtraction—Gas Chromatography—Mass Spectrometry) for volatile compounds (alcohols, ketones, aldehydes, esters, alkenes, alkanes, acids, terpenes) and UHPLC-DAD (Ultra High-Performance Liquid Chromatography—Diode Array Detector) for gentian bitter compounds (seco-iridoids). The sensory analysis consisted of a bitterness rating and a free description of cheeses by 17 trained panelists. Results of the study highlighted that unflavored goat cheeses presented higher unpleasant notes (goaty and lactic whey) and higher amounts of hexanoic acid and toluene compared to gentian flavored goat cheeses. The bitterness of gentian flavored goat cheeses was higher compared to unflavored cheeses and could be explained by loganic acid transfer from yellow gentian to flavored cheeses. Other free descriptors of gentian flavored goat cheeses revealed more complex notes (herbal, vegetal, floral, sweet, spicy and creamy) and higher relative amounts of volatile compounds such as 3-methyl butanoic acid, 2-methyl propanoic acid, 4-methyl decane, 2,3-butanediol, ethanol, diacetyl, methyl acetate and 2-phenylethyl acetate, compared to unflavored cheeses. Phenylethyl acetate was the only volatile compound that enabled differentiation of gentian origin on gentian flavored goat cheeses. Gentian rhizomes could be considered a promising flavoring agent contributing to the olfactive and gustative complexity of flavored goat cheeses and the reduction of their goaty perceptions.

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Murcia, Monica, Olga del Longo, Juan Argüello, Maria Alejandra Perez, and Anna Peretti. "Evaluacion del crecimiento de plántulas de cultivares de girasol con diferentes proporciones de acidos oleico/linoleico en respuesta a la baja temperatura." Revista Brasileira de Sementes 28, no. 2 (2006): 95–101. http://dx.doi.org/10.1590/s0101-31222006000200012.

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El objetivo de este trabajo fue estudiar el vigor a baja temperatura de semillas de girasol con diferente proporción de los ácidos oleico/linoleico, a través de la evaluación del crecimiento de plántulas (pesos secos aéreo y radicular y indice raíz/aéreo) y el tiempo medio de germinación. La proporción oleico/ linoleico de las semillas no se relacionó con el tiempo medio de germinación ni con las variables de crecimiento medidas, ni a temperatura óptima ni a baja temperatura. Los pesos secos aéreo y radicular fueron mayores, en general, en el grupo Alto Linoleico. Sin embargo la variación dentro de cada grupo no permitió asociar la respuesta a la baja temperatura con la composición acídica de los cultivares. Dichas variables se relacionaron con el peso seco de las semillas. Se evidenció respuesta diferencial a la bajas temperatura de las porciones aérea y radicular, con la consiguiente modificación del indice raíz aéreo, variable que tampoco mostró asociación con la composición acídica de los cultivares.

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Ortiz, Darinel, Martina Medkova, Christiane Walch-Solimena, and Peter Novick. "Ypt32 recruits the Sec4p guanine nucleotide exchange factor, Sec2p, to secretory vesicles; evidence for a Rab cascade in yeast." Journal of Cell Biology 157, no. 6 (June 3, 2002): 1005–16. http://dx.doi.org/10.1083/jcb.200201003.

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SEC2 is an essential gene required for polarized growth of the yeast Saccharomyces cerevisiae. It encodes a protein of 759 amino acids that functions as a guanine nucleotide exchange factor for the small GTPase Sec4p, a regulator of Golgi to plasma membrane transport. Activation of Sec4p by Sec2p is needed for polarized transport of vesicles to exocytic sites. Temperature-sensitive (ts) mutations in sec2 and sec4 result in a tight block in secretion and the accumulation of secretory vesicles randomly distributed in the cell. The proper localization of Sec2p to secretory vesicles is essential for its function and is largely independent of Sec4p. Although the ts mutation sec2-78 does not affect nucleotide exchange activity, the protein is mislocalized. Here we present evidence that Ypt31/32p, members of Rab family of GTPases, regulate Sec2p function. First, YPT31/YPT32 suppress the sec2-78 mutation. Second, overexpression of Ypt31/32p restores localization of Sec2-78p. Third, Ypt32p and Sec2p interact biochemically, but Sec2p has no exchange activity on Ypt32p. We propose that Ypt32p and Sec4p act as part of a signaling cascade in which Ypt32p recruits Sec2p to secretory vesicles; once on the vesicle, Sec2p activates Sec4p, enabling the polarized transport of vesicles to the plasma membrane.

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Lian-niang, Li, Xue Hong, Ge Da-lun, Kunio Kangouri, Toshio Miyoshi, and Sadafumi Omura. "Isolation and Structure Elucidation of Seco-neokadsuranic Acid A and 3,4-Seco-(24Z)-lanosta-4(30),8,24-triene-3,26-dioic Acid1." Planta Medica 55, no. 03 (June 1989): 300–302. http://dx.doi.org/10.1055/s-2006-962012.

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Gómez, Willian Rafael, Carlos Enrique Cardona Ayala, and Sandra Rivero. "Producción y calidad del forraje de tres variedades de yuca bajo tres densidades de siembra." Temas Agrarios 21, no. 2 (December 16, 2016): 9–20. http://dx.doi.org/10.21897/rta.v21i2.897.

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Una limitante de la ganadería, de la región Caribe colombiana es la disminución de la producción y calidad del forraje en épocas de sequía o de lluvias. El objetivo del estudio fue evaluar la producción y calidad del forraje de tres variedades de yuca (SM 2546-40, SM 1511-6 y SM 2081-34) bajo tres densidades de siembra (40.000, 55.000 y 70.000 plantas ha-1 ) y tres edades de cosecha (75, 90 y 105 días). El experimento se realizó en el Centro de Investigación Turipaná-Corpoica, en 2011, bajo un diseño de parcelas subdivididas, con tres repeticiones. Se evaluaron las producciones de forraje verde (PFV), materia seca (PMS), proteína bruta (PPB), contenido de proteína bruta (CPB), fibra detergente neutro (FDN), fibra detergente acida (FDA) y cenizas. En el periodo húmedo (mayo-agosto), la PFV y PMS fue 150% más alta que en el seco (enero-abril) y, la de proteína 100% mayor. La variedad de yuca SM 2081-34 produjo mayores PFV y PMS, y menor contenido de FDA. En las tres densidades de siembra las PFV y PMS fueron similares, pero con 55.000 y 70.000 plantas/ha, la PPB fue más alta. A los 105 días, se obtuvieron mayores PFV, PMS y PPB; mientras que, a los 75 días, el forraje presentó menores contenidos de FDN y FDA, y mayor contenido de proteína (CPB). A los 105 días, el contenido de cenizas fue más alto. La variedad SM 2081-34 produjo más materia seca y proteína a los 105 días con 55.000 plantas ha-1 . Palabras clave: Yuca forrajera, materia seca, proteína bruta, fibra detergente ácida.

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Sánchez Gutiérrez, Ricardo A., Héctor Gutiérrez Bañuelos, Alfonso Serna Pérez, Ramón Gutiérrez Luna, and Alejandro Espinoza Canales. "Producción y calidad de forraje de variedades de avena en condiciones de temporal en Zacatecas, México." Revista Mexicana de Ciencias Pecuarias 5, no. 2 (June 7, 2014): 131. http://dx.doi.org/10.22319/rmcp.v5i2.3220.

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Se evaluó la producción, calidad y componentes de rendimiento de seis variedades de avena forrajera en Zacatecas. Los experimentos se establecieron en julio de 2011 y 2012 en el municipio de Monte Escobedo. El diseño experimental fue bloques completos al azar con tres repeticiones, la densidad de siembra fue 120 kg ha-1 y dosis de fertilización de 60-40-00 de N, P2O5, K. La cosecha fue en estado fisiológico lechoso-masoso. En 2011 y 2012, La variedad Saía sobresalió (P<0.05) entre cultivares en rendimiento de forraje seco con 3.7 y 5.6 ha-1, altura de planta con 119 y 120 cm, y en componentes de rendimiento acumuló la mayor (P<0.05) proporción de hoja y tallo. La variedad Karma sobresalió en proporción de espiga con 42 y 49 % (P<0.05) en 2011 y 2012, respectivamente. En proteína cruda losresultados fueron similares (P>0.05) entre variedades con un rango de 10.6 a 13.8 %. En los dos años de estudio Karma presentó las mejores características nutricionales: baja acumulación de fibra detergente neutro (51 %) y acida (33.4 y 35.3 %), valores altos en total de nutrientes digestibles (54 y 58 %), digestibilidad de la materia seca (60 y 62 %), valor relativo del forraje (110 y 113) y energía neta para lactación (1.4 y 1.34 Mcal/kg; P<0.05). Las variables asociadas de manera positiva con forraje seco fueron altura de planta (r=0.701), días a cosecha (r=0.685) y proporción de tallo (r=0.629), y negativamente con proporción de espiga (r=-0.629). En calidad nutricional Karma tuvo mejor valor forrajero. Saia es una buena alternativa para incrementar el rendimiento de forraje por hectárea.

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Nouwen, Nico, Greetje Berrelkamp, and Arnold J. M. Driessen. "Charged Amino Acids in a Preprotein Inhibit SecA-Dependent Protein Translocation." Journal of Molecular Biology 386, no. 4 (March 2009): 1000–1010. http://dx.doi.org/10.1016/j.jmb.2009.01.031.

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Al-Maythalony, Bassem A., M. Monim-ul-Mehboob, Mohammed I. M. Wazeer, Anvarhusein A. Isab, M. Nasiruzzaman Shaikh, and Saleh Altuwaijri. "Synthesis, CP-MAS NMR Characterization, and Antibacterial Activities of Glycine and Histidine Complexes of Cd(SeCN)2and Hg(SeCN)2." Bioinorganic Chemistry and Applications 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/476874.

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The synthesis and characterization of cadmium and mercury complexes of selenocyanate of the type [(L)M(SeCN)2] are described, where L is L-Histidine (His) or L-Glycine (Gly) and M is Cd2+or Hg2+. These complexes are obtained by the reaction of 1 equivalent of respective amino acids with metal diselenocyanate precursor in a mixture of solvents (methanol : water = 1 : 1). These synthesized compounds are characterized by analytical and various spectroscopic techniques such as elemental analysis (EA), IR,H,1andC13NMR in solution and in the solid state forC13andN15. Thein vitroantibacterial activities of these complexes have been investigated with standard type cultures ofEscherichia coli(MTCC 443),Klebsiella pneumoniae(MTCC 109),Pseudomonas aeruginosa(MTCC 1688),Salmonella typhi(MTCC 733), andStaphylococcus aureus(MTCC 737).

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Duque Quintero, Monica, Ricardo Rosero Noguera, and Marta Olivera Ángel. "Digestión de materia seca, proteína cruda y aminoácidos de la dieta de vacas lecheras." Agronomía Mesoamericana 28, no. 2 (April 30, 2017): 341. http://dx.doi.org/10.15517/ma.v28i2.25643.

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The aim of this study was to determine the digestion of dry matter (MS), crude protein (PC) and amino acids (AA) in dairy cows. Two cannulated cows were used for the determination of passage rate (Kp), in situ ruminal degradability (DR) and intestinal digestibility (DI) by abomasal catheter. The data to calculate Kp was analyzed with NLIN procedure by SAS, and descriptive statistics for DR and DI of MS, PC and AA from Kikuyu grass (Pennisetum clandestinum), a commercial supplement and two sources of rumen-protected AA. The study showed a Kp and a ruminal retention time of 0.036 h-1 and 27.4 h. The highest values from DR of MS and CP were from Kikuyu grass (69.0 and 61.8%) and concentrate (84.7 and 77.2%), followed by MetP (60.2 and 66.7%) and LysP (6.72 and 11.4%). The highest percentages of rumen indegradable amino acids (AADR) were from Kikuyu and concentrate, varying between 58.7 and 68% in forage, and 76.1 and 82.9% in the concentrate. The DR was 11.5 and 65.8% in LysP and MetP, respectively. The DI of AA (%AADR) varied between 42.3 and 77.4% for Kikuyu and 42.2 and 59.3% for concentrate. The values for the protected amino acids were 42.1 for LysP and 58.6 for MetP.

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Angulo-Nizama, Manuel Rances, Karen Margori Acuña-Centurion, Majumy Jhomira Arribasplata-Gonzales, Andrea Alejandra Aldea-Garcia, Jhoan Gabriel Aspiros-Anticona, Bill Oscar Arana-Yupanqui, Johnny Alexander Aldana-Carrasca, and Frans Allinson Leiva-Cabrera. "Male sex as a risk factor for Covid-19 complications." Revista Médica de Trujillo 17, no. 4 (December 28, 2022): 150–53. http://dx.doi.org/10.17268/rmt.2022.v17i4.5016.

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In different parts of the world, analyses were made on covid-19 positive cases, reaching the conclusion that the percentage of infected men is higher than that of infected women. Cases from 9 years of age to 90 years of age or older were taken into account. Cases studied by covid were taken into account people suffering from other diseases. ACE2 is the angiotensin-converting enzyme 2, which also acts as a receptor for SARS-CoV 2. This enzyme has a positive correlation with estrogen, this hormone increases the release of acids allowing resistance to this virus. Estrogen was also found to help promote the release of immunoglobulin G and immunoglobulin M. Estrogen also helps release nitric oxide which will help suppress virus replication and acts as a vasodilator, which decreases cardiovascular risk. On the other hand, androgens inhibit the release of immunoglobulin G and immunoglobulin M. This male hormone also has the ability to positively regulate the transcription of transmembrane serine protease 2 which induces the fusion of viral and cell membrane, which is why the virus affects men more severely than women.

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Cox, Randal, Roberta J. Mason-Gamer, Catherine L. Jackson, and Nava Segev. "Phylogenetic Analysis of Sec7-Domain–containing Arf Nucleotide Exchangers." Molecular Biology of the Cell 15, no. 4 (April 2004): 1487–505. http://dx.doi.org/10.1091/mbc.e03-06-0443.

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The eukaryotic family of ADP-ribosylation factor (Arf) GTPases plays a key role in the regulation of protein trafficking, and guanine-nucleotide exchange is crucial for Arf function. Exchange is stimulated by members of another family of proteins characterized by a 200-amino acid Sec7 domain, which alone is sufficient to catalyze exchange on Arf. Here, we analyzed the phylogeny of Sec7-domain–containing proteins in seven model organisms, representing fungi, plants, and animals. The phylogenetic tree has seven main groups, of which two include members from all seven model systems. Three groups are specific for animals, whereas two are specific for fungi. Based on this grouping, we propose a phylogenetically consistent set of names for members of the Sec7-domain family. Each group, except for one, contains proteins with known Arf exchange activity, implying that all members of this family have this activity. Contrary to the current convention, the sensitivity of Arf exchange activity to the inhibitor brefeldin A probably cannot be predicted by group membership. Multiple alignment reveals group-specific domains outside the Sec7 domain and a set of highly conserved amino acids within it. Determination of the importance of these conserved elements in Arf exchange activity and other cellular functions is now possible.

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Eldarov, Chupalav, Alina Gamisonia, Vitaliy Chagovets, Luiza Ibragimova, Svetlana Yarigina, Veronika Smolnikova, Elena Kalinina, et al. "LC-MS Analysis Revealed the Significantly Different Metabolic Profiles in Spent Culture Media of Human Embryos with Distinct Morphology, Karyotype and Implantation Outcomes." International Journal of Molecular Sciences 23, no. 5 (February 28, 2022): 2706. http://dx.doi.org/10.3390/ijms23052706.

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In this study we evaluated possible differences in metabolomic profiles of spent embryo culture media (SECM) of human embryos with distinct morphology, karyotype, and implantation outcomes. A total of 153 samples from embryos of patients undergoing in vitro fertilization (IVF) programs were collected and analyzed by HPLC-MS. Metabolomic profiling and statistical analysis revealed clear clustering of day five SECM from embryos with different morphological classes and karyotype. Profiling of day five SECM from embryos with different implantation outcomes showed 241 significantly changed molecular ions in SECM of successfully implanted embryos. Separate analysis of paired SECM samples on days three and five revealed 46 and 29 molecular signatures respectively, significantly differing in culture media of embryos with a successful outcome. Pathway enrichment analysis suggests certain amino acids, vitamins, and lipid metabolic pathways to be crucial for embryo implantation. Differences between embryos with distinct implantation potential are detectable on the third and fifth day of cultivation that may allow the application of culture medium analysis in different transfer protocols for both fresh and cryopreserved embryos. A combination of traditional morphological criteria with metabolic profiling of SECM may increase implantation rates in assisted reproductive technology programs as well as improve our knowledge of the human embryo metabolism in the early stages of development.

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A.A., Opeyemi, Moses A.A., and Andrew B.O. "Cooking Methods Revealed Differences in Quality Content of Prepared Soyabean Extended Chicken Nuggets." African Journal of Agriculture and Food Science 5, no. 3 (August 23, 2022): 12–27. http://dx.doi.org/10.52589/ajafs-ukdnf8du.

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Soyabean extended chicken nuggets (SECN) were prepared, separately fried, grilled and roasted. The cooked nuggets were formulated as diets and fed to weaning rats (n=50) using standard casein and nitrogen free diets as controls. Quality attributes were assessed based on physico-chemical, sensory properties, proximate compositions, amino acids, total cholesterol and shelf stability in terms of lipid oxidation and microbial load as well as the effect of the feed on growth performance of weaned albino rats. Apart from slight variation (P<0.05), fried SECN, followed by grilled SECN improved yield, flavour, overall acceptability, crude protein and amino acid content in comparison to roasted SECN. The reduced lipid oxidation, total cholesterol and microbial load further enhanced the quality of fried SECN. Similarly, fried SECN was considered as the best based on daily feed intake, weight gained, feed conversion ratio, protein efficiency ratio and biological value. Thus, among the different cooking methods, deep-frying enhanced the quality of SECN better than other cooking methods as reflected in growth performance of weaned albino rats. Therefore, to harness acceptability of chicken nuggets, soyabean protein extender which is known for its ability to improve product firmness, chewiness and emulsion stability could be used alongside appropriate cooking methods to prepare chicken nuggets with excellent structural and nutritional qualities readily acceptable by consumers.

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Hikota, Masataka, Hitoshi Tone, Kiyoshi Horita, and Osamu Yonemitsu. "Stereoselective synthesis of erythronolide a by extremely efficient lactonization based on conformational adjustment and high activation of seco-acid1." Tetrahedron 46, no. 13-14 (January 1990): 4613–28. http://dx.doi.org/10.1016/s0040-4020(01)85585-x.

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Bensing, Barbara A., and Paul M. Sullam. "Characterization of Streptococcus gordonii SecA2 as a Paralogue of SecA." Journal of Bacteriology 191, no. 11 (April 10, 2009): 3482–91. http://dx.doi.org/10.1128/jb.00365-09.

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ABSTRACT The accessory Sec system of Streptococcus gordonii is essential for transport of the glycoprotein GspB to the bacterial cell surface. A key component of this dedicated transport system is SecA2. The SecA2 proteins of streptococci and staphylococci are paralogues of SecA and are presumed to have an analogous role in protein transport, but they may be specifically adapted for the transport of large, serine-rich glycoproteins. We used a combination of genetic and biochemical methods to assess whether the S. gordonii SecA2 functions similarly to SecA. Although mutational analyses demonstrated that conserved amino acids are essential for the function of SecA2, replacing such residues in one of two nucleotide binding folds had only minor effects on SecA2 function. SecA2-mediated transport is highly sensitive to azide, as is SecA-mediated transport. Comparison of the S. gordonii SecA and SecA2 proteins in vitro revealed that SecA2 can hydrolyze ATP at a rate similar to that of SecA and is comparably sensitive to azide but that the biochemical properties of these enzymes are subtly different. That is, SecA2 has a lower solubility in aqueous solutions and requires higher Mg2+ concentrations for maximal activity. In spite of the high degree of similarity between the S. gordonii paralogues, analysis of SecA-SecA2 chimeras indicates that the domains are not readily interchangeable. This suggests that specific, unique contacts between SecA2 and other components of the accessory Sec system may preclude cross-functioning with the canonical Sec system.

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