Academic literature on the topic 'Gamma-ammino acidi beta,beta-disostituiti'
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Journal articles on the topic "Gamma-ammino acidi beta,beta-disostituiti"
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Liakopoulou, E., CA Blau, Q. Li, B. Josephson, JA Wolf, B. Fournarakis, V. Raisys, G. Dover, T. Papayannopoulou, and G. Stamatoyannopoulos. "Stimulation of fetal hemoglobin production by short chain fatty acids." Blood 86, no. 8 (October 15, 1995): 3227–35. http://dx.doi.org/10.1182/blood.v86.8.3227.3227.
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Abstract Butyrate, a four-carbon fatty acid, and its two-carbon metabolic product, acetate, are inducers of gamma-globin synthesis. To test whether other short-chain fatty acids share this property, we first examined whether propionic acid, a three-carbon fatty acid that is not catabolized to acetate, induces gamma-globin expression. Sodium propionate increased the frequency of fetal hemoglobin containing erythroblasts and the gamma/gamma + beta mRNA ratios in adult erythroid cell cultures and F reticulocyte production in a nonanemic juvenile baboon. Short-chain fatty acids containing five (pentanoic), six (hexanoic), seven (heptanoic), eight (octanoic), and nine (nonanoic) carbons induced gamma-globin expression (as measured by increase in gamma-positive erythroblasts and gamma/gamma + beta mRNA ratios) in adult erythroid burst-forming unit cultures. There was a clear-cut relationship between the concentration of fatty acids in culture and the degree of induction of gamma-globin expression. Three-, four-, and five-carbon fatty acids were better inducers of gamma globin in culture as compared with six- to nine-carbon fatty acids. These results suggest that all short-chain fatty acids share the property of gamma-globin gene inducibility. The fact that valproic acid, a derivative of pentanoic acid, also induces gamma-globin expression suggests that short-chain fatty acid derivatives that are already approved for human use may possess the property of gamma-globin inducibility and may be of therapeutic relevance to the beta-chain hemoglobinopathies.
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Liakopoulou, E., CA Blau, Q. Li, B. Josephson, JA Wolf, B. Fournarakis, V. Raisys, G. Dover, T. Papayannopoulou, and G. Stamatoyannopoulos. "Stimulation of fetal hemoglobin production by short chain fatty acids." Blood 86, no. 8 (October 15, 1995): 3227–35. http://dx.doi.org/10.1182/blood.v86.8.3227.bloodjournal8683227.
Full textAbstract:
Butyrate, a four-carbon fatty acid, and its two-carbon metabolic product, acetate, are inducers of gamma-globin synthesis. To test whether other short-chain fatty acids share this property, we first examined whether propionic acid, a three-carbon fatty acid that is not catabolized to acetate, induces gamma-globin expression. Sodium propionate increased the frequency of fetal hemoglobin containing erythroblasts and the gamma/gamma + beta mRNA ratios in adult erythroid cell cultures and F reticulocyte production in a nonanemic juvenile baboon. Short-chain fatty acids containing five (pentanoic), six (hexanoic), seven (heptanoic), eight (octanoic), and nine (nonanoic) carbons induced gamma-globin expression (as measured by increase in gamma-positive erythroblasts and gamma/gamma + beta mRNA ratios) in adult erythroid burst-forming unit cultures. There was a clear-cut relationship between the concentration of fatty acids in culture and the degree of induction of gamma-globin expression. Three-, four-, and five-carbon fatty acids were better inducers of gamma globin in culture as compared with six- to nine-carbon fatty acids. These results suggest that all short-chain fatty acids share the property of gamma-globin gene inducibility. The fact that valproic acid, a derivative of pentanoic acid, also induces gamma-globin expression suggests that short-chain fatty acid derivatives that are already approved for human use may possess the property of gamma-globin inducibility and may be of therapeutic relevance to the beta-chain hemoglobinopathies.
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Nishikawa, Koichi, and Neil L. Harrison. "The Actions of Sevoflurane and Desflurane on the γ-Aminobutyric Acid Receptor Type A." Anesthesiology 99, no. 3 (September 1, 2003): 678–84. http://dx.doi.org/10.1097/00000542-200309000-00024.
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Background Previous studies have shown that specific amino acid residues in the putative second transmembrane segment (TM2) of the gamma-aminobutyric acid receptor type A (GABAA) receptor play a critical role in the enhancement of GABAA receptor function by halothane, enflurane, and isoflurane. However, very little is known about the actions of sevoflurane and desflurane on recombinant GABAA receptors. The aim of this study was to examine the effects of sevoflurane and desflurane on potentiation of GABA-induced responses in the wild-type GABAA receptor and in receptors mutated in TM2 of the alpha1, alpha 2, or beta 2 subunits. Methods GABAA receptor alpha 1 or alpha 2, beta 2 or beta 3, and gamma 2s subunit cDNAs were expressed for pharmacologic study by transfection of human embryonic kidney 293 cells and assayed using the whole cell voltage clamp technique. Concentration-response curves and EC50 values for agonist were determined in the wild-type alpha 1 beta 2 gamma 2s and alpha 2 beta 3 gamma 2s receptors, and in receptors harboring mutations in TM2, such as alpha1(S270W)beta 2 gamma 2s, alpha 1 beta 2(N265W)gamma 2s, and alpha2(S270I)beta 3 gamma 2s. The actions of clinically relevant concentration of volatile anesthetics (isoflurane, sevoflurane, and desflurane) on GABA activated Cl- currents were compared in the wild-type and mutant GABAA receptors. Results Both sevoflurane and desflurane potentiated submaximal GABA currents in the wild-type GABAA alpha 1 beta 2 gamma 2s receptor and alpha 2 beta 3 gamma 2s receptor. Substitution of Ser270 in TM2 of the alpha subunit by a larger amino acid, tryptophan (W) or isoleucine (I), as in alpha1(S270W)beta 2 gamma 2s and alpha 2(S270I)beta 3 gamma 2s, completely abolished the potentiation of GABA-induced currents by these anesthetic agents. In contrast, mutation of Asn265 in TM2 of the beta subunit to tryptophan (W) did not prevent potentiation of GABA-induced responses. The actions of sevoflurane and desflurane in the wild-type receptor and in mutated receptors were qualitatively and quantitatively similar to those observed for isoflurane. Conclusions Positions Ser270 of the GABAA alpha1 and alpha2 subunits, but not Asn265 in the TM2 of the beta2 subunit, are critical for regulation of the GABAA receptor by sevoflurane and desflurane, as well as isoflurane, consistent with the idea that these three volatile anesthetics share a common site of actions on the alpha subunit of the GABAA receptor.
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Desai, Rooma, Dirk Ruesch, and Stuart A. Forman. "γ-Amino Butyric Acid Type A Receptor Mutations at β2N265 Alter Etomidate Efficacy While Preserving Basal and Agonist-dependent Activity." Anesthesiology 111, no. 4 (October 1, 2009): 774–84. http://dx.doi.org/10.1097/aln.0b013e3181b55fae.
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Background Etomidate acts at gamma-Aminobutyric acid type A (GABAA) receptors containing beta2 or beta3, but not beta1 subunits. Mutations at beta residue 265 (Ser in beta1; Asn in beta2 or beta3) profoundly affect etomidate sensitivity. Whether these mutations alter etomidate binding remains uncertain. Methods Heterologously expressed alpha1beta2gamma2L GABAA receptors and receptors with beta2(N265S) or beta2(N265M) mutations were studied electrophysiologically in both Xenopus oocytes and HEK293 cells. Experiments quantified the impact of beta2N265 mutations or substituting beta1 for beta2 on basal channel activation, GABA EC50, maximal GABA efficacy, etomidate-induced leftward shift in GABA responses, etomidate direct activation, and rapid macrocurrent kinetics. Results were analyzed in the context of an established allosteric co-agonist mechanism. Results Mutations produced only small changes in basal channel activity, GABA EC50, maximal GABA efficacy, and macrocurrent kinetics. Relative to wild-type, beta2(N265S) reduced etomidate enhancement of apparent GABA affinity six-fold, and it reduced etomidate direct activation efficacy 14-fold. beta2(N265M) totally eliminated both etomidate modulation of GABA responses and direct channel activation. Mechanism-based analysis showed that the function of both mutants remains consistent with the allosteric co-agonist model and that beta2(N265S) reduced etomidate allosteric efficacy five-fold, whereas etomidate-binding affinity dropped threefold. Experiments swapping beta2 subunits for beta1 indicated that etomidate efficacy is reduced 34-fold, whereas binding affinity drops less than two-fold. Conclusions Mutations at beta2N265 profoundly alter etomidate sensitivity with only small changes in basal and GABA-dependent channel activity. Mutations at the beta2N265 residue or replacement of beta2 with beta1 influence etomidate efficacy much more than binding to inactive receptors.
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Husmann, M., J. Lehmann, B. Hoffmann, T. Hermann, M. Tzukerman, and M. Pfahl. "Antagonism between retinoic acid receptors." Molecular and Cellular Biology 11, no. 8 (August 1991): 4097–103. http://dx.doi.org/10.1128/mcb.11.8.4097-4103.1991.
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In the developing mouse, retinoic acid receptors (RARs) beta and gamma 1 are expressed in characteristic spatiotemporal patterns which are correlated with different developmental fates of the respective tissues. Understanding the cues that regulate the expression of the various RARs may therefore provide insights into the process of tissue diversification. Transcription of RAR beta is rapidly upregulated through a retinoic acid-responsive element (here referred to as the beta RARE) in its promoter. Like RAR alpha and RAR beta, RAR gamma 1 has been implicated in the activation of the beta RARE. Therefore, it is puzzling that RAR beta and RAR gamma 1 appear to be expressed in reciprocal patterns. In the present report, we show that RAR gamma 1, one of the two predominant RAR gamma isoforms, can inhibit the activity of RAR gamma 2, RAR beta, and endogenous RAR on the beta RARE. In contrast, the three RAR gamma isoforms tested and RAR beta activated a palindromic thyroid hormone response element with similar levels of efficiency. The differential activity of RAR gamma 1 compared with that of RAR beta appears to reside in both the N-terminal and the C-terminal halves of RAR gamma 1. RAR gamma 1-mediated inhibition of other RARs may involve competition for the response element as well as direct interaction with other receptors and might be part of a regulatory system contributing to the characteristic tissue distribution of the various RARs.
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Husmann, M., J. Lehmann, B. Hoffmann, T. Hermann, M. Tzukerman, and M. Pfahl. "Antagonism between retinoic acid receptors." Molecular and Cellular Biology 11, no. 8 (August 1991): 4097–103. http://dx.doi.org/10.1128/mcb.11.8.4097.
Full textAbstract:
In the developing mouse, retinoic acid receptors (RARs) beta and gamma 1 are expressed in characteristic spatiotemporal patterns which are correlated with different developmental fates of the respective tissues. Understanding the cues that regulate the expression of the various RARs may therefore provide insights into the process of tissue diversification. Transcription of RAR beta is rapidly upregulated through a retinoic acid-responsive element (here referred to as the beta RARE) in its promoter. Like RAR alpha and RAR beta, RAR gamma 1 has been implicated in the activation of the beta RARE. Therefore, it is puzzling that RAR beta and RAR gamma 1 appear to be expressed in reciprocal patterns. In the present report, we show that RAR gamma 1, one of the two predominant RAR gamma isoforms, can inhibit the activity of RAR gamma 2, RAR beta, and endogenous RAR on the beta RARE. In contrast, the three RAR gamma isoforms tested and RAR beta activated a palindromic thyroid hormone response element with similar levels of efficiency. The differential activity of RAR gamma 1 compared with that of RAR beta appears to reside in both the N-terminal and the C-terminal halves of RAR gamma 1. RAR gamma 1-mediated inhibition of other RARs may involve competition for the response element as well as direct interaction with other receptors and might be part of a regulatory system contributing to the characteristic tissue distribution of the various RARs.
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Friedrich, R. J., K. S. Campbell, and J. C. Cambier. "The gamma subunit of the B cell antigen-receptor complex is a C-terminally truncated product of the B29 gene." Journal of Immunology 150, no. 7 (April 1, 1993): 2814–22. http://dx.doi.org/10.4049/jimmunol.150.7.2814.
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Abstract The predominant Ag-receptor complex of B cells consists of mIgM or mIgD noncovalently associated with glycosylated heterodimers of Ig-alpha and Ig-beta or Ig-alpha and Ig-gamma. Upon B cell stimulation the associated proteins are phosphorylated, giving rise to pp32/33 (alpha), pp37 (beta), and pp34 (previously designated gamma). Ig-alpha and Ig-beta contain extended cytoplasmic structure (61 and 48 amino acids, respectively) and associate with cytoplasmic effectors indicating that they are directly involved in signal transduction. Here we report analysis of the structural relationship of mIgM- and mIgD-associated Ig-beta and Ig-gamma chains from mice. N-terminal sequence, immunoblotting, and physicochemical analyses show that both Ig-beta and Ig-gamma are products of the B cell-specific B29 gene and demonstrate that the 37-kDa Ig-beta protein is the full length predicted product of the B29 gene. The Ig-associated protein that migrates in the 34-kDa range is actually two distinct species. The minor species is a phosphorylatable and underglycosylated form of full length Ig-beta, and the major species is a C-terminally truncated form of B29, which we now designate Ig-gamma. This conclusion is based on the observations that Ig-gamma is composed of a core protein which is 3 to 4 kDa smaller than deglycosylated Ig-beta, it is not phosphorylated, unlike Ig-beta, and it does not react with an antiserum raised against a peptide of the seven C-terminal amino acids of B29. Based on these findings we estimate that Ig-gamma is truncated by about 30 to 36 amino acid residues and hypothesize that the most 3' B29 exon, which encodes the 32 C-terminal residues, may not be expressed in Ig-gamma. All of the documented B29 products are found in association with both mIgM and mIgD. Interestingly, Ig-gamma is found in intermediate and low density splenic B cells, but is not detectable in resting B cells. This raises the possibility that it may confer some distinct signaling function on the Ag receptors of these cells.
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Pace, B., Q. Li, K. Peterson, and G. Stamatoyannopoulos. "alpha-Amino butyric acid cannot reactivate the silenced gamma gene of the beta locus YAC transgenic mouse." Blood 84, no. 12 (December 15, 1994): 4344–53. http://dx.doi.org/10.1182/blood.v84.12.4344.bloodjournal84124344.
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Butyric acid, a naturally occurring fatty acid, has been shown to increase fetal hemoglobin in BFUe cultures, in primates, and in patients with beta chain hemoglobinopathies. The precise mechanism of gamma gene induction by butyrate is unknown. Butyrate may induce fetal hemoglobin production in vivo by reactivation of silenced gamma globin genes, by inhibiting the silencing of gamma genes, or by both mechanisms. We examined the effects of butyrate on gamma gene expression in transgenic mice carrying three types of constructs: microLCRA gamma mice, which continue to express the gamma gene in the adult stage of development at a level of one-third to one-fifth of the expression in the fetus; microLCRA gamma psi beta delta beta mice, which display correct developmental regulation of gamma and beta human globin genes and have low level gamma globin expression in the adult; and beta locus YAC mice, which display correct developmental regulation of epsilon, gamma, and beta globin genes and have a totally silenced gamma gene in the adult stage. Animals were treated with a continuous infusion of alpha-amino butyric acid (alpha-ABA) for 7 days. In microLCRA gamma mice alpha-ABA produced up to a 43-fold induction of gamma and 9-fold induction of mouse alpha globin genes. In contrast, butyrate did not induce gamma globin expression in the beta locus YAC mice. However, the gamma globin genes of beta locus YAC mice were activated after administration of 5-azacytidine (5-azaC), and the level of gamma globin expression was further increased by administration of alpha-ABA. These results suggest that butyrate cannot reactivate a totally silenced gamma gene and that induction of fetal hemoglobin by this compound may require the presence of preactivated gamma globin genes.
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Munck, B. G., L. K. Munck, S. N. Rasmussen, and A. Polache. "Specificity of the imino acid carrier in rat small intestine." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 266, no. 4 (April 1, 1994): R1154—R1161. http://dx.doi.org/10.1152/ajpregu.1994.266.4.r1154.
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The rat intestinal imino acid carrier is chloride independent, while in guinea pig and rabbit intestine it is chloride dependent. While non-alpha-amino acids do not significantly interact with guinea pig and rabbit imino acid carriers, inhibition studies had indicated that in rat small intestine beta-alanine, gamma-aminobutyric acid (GABA), and probably taurine might be transported by the imino acid carrier. The present study of rat jejunum demonstrates that the half-maximal activation concentration of beta-alanine (K1/2 beta-Ala) is identical to its inhibition constant (Ki beta-Ala) against GABA, that K1/2GABA is identical to KiGABA against beta-alanine, that proline and sarcosine have identical values of Ki against beta-alanine and GABA, and that Ki of beta-alanine and proline against sarcosine are equal to their K1/2 values. Taurine inhibits the transport of beta-alanine, and 300 mM proline and beta-alanine reduce the transport of taurine measured at 80 mM taurine to the level expected for the diffusive contribution, corresponding to Ki values equal to those against sarcosine. Thus the rat imino acid carrier is the principal carrier of taurine and the only carrier of beta-alanine and GABA. It is also demonstrated that alpha-amino-monocarboxylic acids with side chains in excess of one methyl group do not significantly interact with the imino acid carrier, and the lack of stereospecificity is confirmed.
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Gugneja, S., J. V. Virbasius, and R. C. Scarpulla. "Four structurally distinct, non-DNA-binding subunits of human nuclear respiratory factor 2 share a conserved transcriptional activation domain." Molecular and Cellular Biology 15, no. 1 (January 1995): 102–11. http://dx.doi.org/10.1128/mcb.15.1.102.
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Nuclear respiratory factor 2 (NRF-2) was previously purified to near homogeneity from HeLa cells on the basis of its ability to bind tandem recognition sites in the rat cytochrome oxidase subunit IV (RCO4) promoter. It consisted of five subunits, alpha, beta 1, beta 2, gamma 1, and gamma 2. Sequencing of tryptic peptides from alpha and from mixtures of the two beta or two gamma subunits revealed sequence identities with subunits of the mouse GA-binding protein (GABP), a ubiquitously expressed ETS domain activator composed of three subunits, alpha, beta 1, and beta 2. To understand the precise relationship between NRF-2 and GABP, cDNAs for all five NRF-2 subunits have now been cloned and their products have been overexpressed. The results establish that the two additional NRF-2 subunits are molecular variants that differ from GABP beta 1 and beta 2 by having a 12-amino-acid insertion containing two serine doublets. PCR and RNase protection assays show that mRNAs for these variants are expressed in the human but not the rodent cells and tissues examined. The insertion did not alter the ability of the beta and gamma subunits to associate with alpha, the DNA-binding subunit, nor did it affect the ability of NRF-2 beta 1 or beta 2 to direct high-affinity binding of alpha to tandem sites in the RCO4 promoter. In addition, the four NRF-2 beta and gamma subunits were equally proficient in activating transcription in transfected cells when fused to a GAL4 DNA-binding domain. The domain responsible for this transcriptional activation was localized by deletion mapping to a region of approximately 70 amino acids that is conserved in all four NRF-2 beta and gamma subunits. The repeated glutamine-containing hydrophobic clusters within this region bear a strong resemblance to those recently implicated in protein-protein interactions within the transcriptional apparatus.
Dissertations / Theses on the topic "Gamma-ammino acidi beta,beta-disostituiti"
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Venneri, Cesare Daniele. "Sintesi stereoselettiva mediata da enzimi di analoghi lineari e ciclici dell'acido Ÿ- amminobutirrico." Doctoral thesis, Università degli studi di Trieste, 2010. http://hdl.handle.net/10077/3517.
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2008/2009E’ stata sviluppata una sintesi enantioselettiva facile e rapida di una serie di analoghi del GABA beta-sostituiti e beta,beta’-disostituiti potenzialmente utili, a partire da precursori gamma-nitro esterei racemi facilmente disponibili, attraverso la loro risoluzione cinetica enzimatica. L'applicazione della procedura descritta al substrato che reca in posizione beta il raggruppamento isobutilico consente di ottenere il composto terapeuticamente utile (S)-(+)-Pregabalina e la sua controparte enantiomerica; la medesima strategia sintetica applicata al substrato beta,beta’-disostituito con i gruppi metile e isobutile conduce all’analogo tetrasostituito della stessa Pregabalina, mentre il substrato recante in beta,beta’ il gruppo 3-metilcicloesile permette l’ottenimento di un analogo chirale della Gabapentina (Neurontin®) e del suo enantiomero. L’interesse verso la sintesi di gamma-amminoacidi beta,beta’-sostituiti risiede non solo nella potenziale attività biologica dei composti target, analoghi chirali della Gabapentina, ma è anche in relazione al problema sintetico connesso con l’ottenimento di composti chirali in cui l’atomo di carbonio asimmetrico è quaternario. I risultati ottenuti sono di notevole interesse anche alla luce della nota riluttanza delle comuni idrolasi a riconoscere e trasformare substrati in cui il centro chirale adiacente alla funzione idrolizzabile è completamente sostituito. La medesima procedura rappresenta inoltre una strategia sintetica alternativa per acidi 2-alchilsuccinici otticamente attivi, che possono essere così ottenuti in condizioni relativamente blande. Infatti la trasformazione di un nitrocomposto primario in un acido carbossilico, nota come reazione di Victor Meyer, richiede condizioni drastiche, cioè trattamento a riflusso con acidi minerali, oppure laboriose procedure di sintesi. Gli acidi succinici, oltre a manifestare varie attività a livello biologico, sono utili intermedi sintetici per importanti building blocks omochirali come beta-lattami, beta- e gamma-lattoni, succinimidi, anidridi succiniche. Nell’ambito della sintesi degli analoghi del GABA beta,beta’-sostituiti, inoltre, parallelamente al lavoro con gli enzimi è stata sviluppata un’addizione coniugata diretta e altamente enantioselettiva di un nitroalcano ad un’aldeide alfa,beta-insatura usando difenilprolinol silil etere come organocatalizzatore, per ottenere un intermedio prontamente convertito nell’amminoacido target. Questa concisa, pratica ed efficiente procedura sintetica si ritiene possa trovare ampia applicabilità nella sintesi stereoselettiva di altri composti recanti un carbonio quaternario chirale, di difficile ottenimento, e, in particolare, di altri gamma-amminoacidi beta,beta-dialchilati enantiopuri di interesse chimico e farmaceutico. Si presenta infine un’efficiente sintesi dell’acido 2-carbossi-3-pirrolidinacetico, gamma-amminoacido conformazionalmente costretto e importante agonista del recettore NMDA (N-metil-D-aspartato) che costituisce lo scheletro degli acidi kainici, dotati, fra le varie azioni biologiche, di attività neuroeccitatoria. La strategia sintetica proposta conduce ad elevati eccessi enantiomerici e rese soddisfacenti.
XXII Ciclo
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Abarbri, Mohamed. "Acides Alpha-Beta et Beta-Gamma insaturés : préparation, réactivité et utilisation en synthèse organique." Tours, 1995. http://www.theses.fr/1995TOUR4014.
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Les acides but-3-enoiques substitues en position 3 sont préparés par substitution de l'acide 3-iodobut-3-enoique par des organozinciques ou organostanniques en présence de complexes de palladium et du dmf. Cette étude a été étendue aux dérivés de l'acide 3-iodopropénoique (z ou e) pour préparer des acides alpha-beta insaturés substitues en position beta. Nous avons montré que l'utilisation d'acétylures de zinc en présence d'un complexe de palladium ii peut s'avérer une méthode très efficace pour préparer, d'une façon stéréosélective, des composés possédant des structures enynoiques fonctionnelles porteuses notamment de la fonction acétal. De plus, nous avons montré que le couplage de vinylétains avec ces acides beta iodé conduit stéréosélectivement a des structures diénoiques. Les possibilites offertes par la synthèse de ces oléfines substituées, en particulier, le deuxième site électrophile qu'est la fonction acide a permis de synthétiser des molécules terpéniques telles que les ocimenones, la () ar-turmerone, les pseudotagetones et des amides naturels tels que la pellitorine et la kalecide. Les résultats obtenus au cours de ce travail apparaissent comme une contribution a la synthèse stéréospécifique d'oléfines di- ou trisubstituées porteuses d'une fonction acide.
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Zhang, Jing. "Synthesis of phosphinic acids and aza-beta and gamma-lactams as potential inhibitors of bacterial D,D-peptidases and beta-lactamases." Université catholique de Louvain, 2003. http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-09292003-151944/.
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Grison, Claire. "Peptides-beta/gamma mixtes : nouveaux édifices foldamères pour mimer l'hélice-alpha." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS128/document.
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Cette thèse est consacrée à la synthèse et à l'étude structurale de peptides-beta/gamma, contenant en alternance des acides aminés-beta et -gamma, conçus pour mimer l'hélice-alpha (ou hélice-13), structure secondaire des protéines. Nous avons ainsi élaboré une stratégie de design « bottom-up » pour des peptides-beta/gamma devant se replier sous forme d'hélice-13. Ces peptides comportent un acide aminé-beta, le (1S,2S)-trans-2-aminocyclobutanecarboxylique, qui joue un rôle clé de brique constitutive en apportant des contraintes conformationnelles. Dans un premier temps, la synthèse énantiomériquement pure du trans-ACBC basée sur une étape clé de photocycloaddition [2+2] a été optimisée. Il a alors été possible de synthétiser des peptides-beta/gamma incorporant en alternance le trans-ACBC et le GABA, qui est un acide aminé-gamma dépourvu de toute contrainte. Des études expérimentales et théoriques fines de ces peptides-beta/gamma ont révélé une structuration inédite sous forme de rubban-9/8, en solution. Il a été démontré que ces nouveaux foldamères adoptent une forme plus ou moins courbe gouvernée par un code combinant configuration et conformation des acides aminés constitutifs de ces peptides. Dans un deuxième temps, des contraintes sur l'acide aminé-gamma ont été introduites par la préparation de peptides-beta/gamma alternant le trans-ACBC et des acides aminés-gamma4. Des études expérimentales et théoriques de ces peptides-beta/gamma en solution ont révélé une préférence conformationnelle sous forme d'hélice-13. La stabilité de cette structure hélicoïdale augmente avec la longueur de la chaîne peptidique. Ces hélices-13 sont en effet fortement stabilisées à partir de 5 liaisons hydrogènes inter-résidus. Enfin, des peptides-alpha/beta/gamma capables de mimer l'hélice-alpha du peptide p53(15-31) ont été conçus et synthétisés, afin de vérifier expérimentalement leur hélicité prédite par modélisation moléculaire. Une fois leur résistance à la dégradation protéolytique démontrée, ces peptides-alpha/beta/gamma ont été testés comme inhibiteur de l'interaction p53/hDM2. Un candidat a particulièrement été capable d'inhiber cette interaction en se liant au site naturel de fixation avec la protéine hDM2. Ce résultat illustre la réussite de notre stratégie de construction de mimes de l'hélice-alphaThis thesis is devoted to the synthesis and the structural characterisation of beta/gamma-peptides, constructed from beta- and gamma-amino acids in alternation, designed to mimic the alpha-helix secondary structure which is present in many native proteins. The alpha-helix can be defined as a 13-helix and a bottom-up foldamer design strategy to target a 13-helical structure was examined, whereby beta/gamma-peptides were proposed in which (1S,2S)-trans-2-aminocyclobutanecarboxylic acid (trans-ACBC) was incorporated as a conformationally-restricted beta-amino acid component. The scalable synthesis of enantiomerically pure trans-ACBC using a [2+2] photocycloaddition strategy was successfully optimized. beta/gamma-Peptides incorporating trans-ACBC and GABA, the latter being the gamma-amino acid component devoid of any constraint, were then synthesised. Experimental and theoretical investigations of their solution-state folding behaviour revealed an unprecedented 9/8-ribbon foldamer structure that adopts curved shapes governed by a combined configuration-conformation code. Additional constraints on the gamma-amino acid component were then considered and beta/gamma-peptides incorporating trans-ACBC and gamma4-amino acids were synthesised. Experimental and theoretical investigations of these beta/gamma-peptides in solution unveiled a preference for 13-helix folding behaviour, which increased commensurately with the peptide chain length; robust 13-helices were stabilised by a minimum of five intramolecular hydrogen bonds. In the last part of this thesis, molecular modelling was used to design helical alpha/beta/gamma-peptides intended to reproduce as closely as possible the hot-spot residues of the known alpha-helical peptide sequence p53(15-31). These peptides were synthesised and their predicted helical folding was verified experimentally along with their resistance to proteolytic enzymes. The alpha/beta/gamma-peptides were tested as inhibitors of the p53/hDM2 interaction. One peptide was found to behave as potent inhibitor and to bind to the native peptide binding pocket of the hDM2 protein, providing a successful proof of concept of the alpha-helix mimetic design strategy
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Chapman, Mark Andrew. "The synthesis of #beta#,#gamma#-ethynyldiaminopimelic acid analogues as potential chemotherapeutic agents." Thesis, University of Sunderland, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294051.
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Tercinier, Pierre. "Etude de la préparation et de la réactivité des 2,3-aziridino-γ-lactones : approche à la synthèse de l’apto, acide ß-amine composant des microsclérodermines C et D." Paris 11, 2007. http://www.theses.fr/2007PA112080.
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Les travaux décrits dans cette thèse s'articulent autour de la réactivité et de la synthèse de composés bicycliques chiraux, les 2,3-aziridino-gamma-Iactones et leur utilisation pour 1âpréparation d'acides beta-aminés polysubstitués. Nous avons d'abord étudié la réactivité des 2,3-aziridino-gamma-Iactones vis-à-vis de nucléophiles mous carbonés tel que des organocuprates. Pour cela, différentes aziridines ont été préparées à partir de la D-ribonolactone puis mises en réaction avec différents nucléophiles carbonés. Ainsi nous avons pu introduire de manière régiosélective un groupement méthyle en position C-2, le composé obtenu étant néanmoins accompagné de produits secondaires. Nous avons ensuite utilisé ces composés bicycliques chiraux dans le cadre de la synthèse de l'APTO, acide beta-aminé polysubstitué composant des microsclérodermines C et D. Ainsi, nous avons développé une synthèse énantiospécifique d'un précurseur cyclique de l'APTO au départ du L-gulose. Cette stratégie est basée sur la préparation de l'aziridineelactone appropriée suivie de l'ouverture régiosélective en C-2 de l'aziridine et d'une réaction de Heck. Ce composé a pu être ouvert par différents nucléophiles aminés montrant ainsi son potentiel synthétique. Enfin, nous avons étudié une nouvelle voie d'accès aux 2,3-aziridino-gamma-Iactones à partir d'un sulfamate insaturé. Cette aziridination intramoléculaire par transfert de nitrène se fait par catalyse au rhodium, médiée par le diacétate d'iodosylbenzène. Ce procédé permet d'obtenir des 2,3-aziridino-gamma-Iactones de stéréochimie différente de celles préparées par la méthode précédente, et donc d'accéder à de nouveaux acides beta-aminésThe work described in this thesis concems the synthesis and reactiviy of chiral bicyclic compounds, 2,3gamma-Iactones, and their use in the preparation ofpolysubstituted beta-amino acids. The reactivity of 2,3-aziridino-gamma-Iactones with soft carbon nucleophiles such as organocuprates was first studied. Different aziridines were prepared and reacted with various carbon nucleophiles. A methyl group was successfully introduced at the C-2 position but this was accompanied by the formation of many by-products. The 2,3-aziridino-gamma-Iactones were then used to synthesize APTO, a polysubstituted beta-amino acid fragment of microsclerodermines C and D. An enantiospecific synthesis of a cyclic precursor of APTO was developed starting from L-gulose. This strategy is based upon the preparation of the appropriate aziridine-Iactone, followed by regioselective CC2 ring-opening by an acetate and a Heck reaction. This intermediate was successfully opened by various amines, demonstrating its synthetic potential. Lastly, a new process for the preparation of 2,3-aziridino-gamma-Iactones starting from an unsaturated sulfamate was studied. This intramolecular nitrene transfer aziridination was catalyzed by rhodium salts and mediated by iodosylbenzene diacetate. This new methodology allowed the preparation of 2,3-aziridino-gamma-Iactones with a different stereochemistry than those synthesized previously, potentially leading to new beta-amino acids
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Mähl, Philipp Henning. "Die Proteinkinase A-vermittelte Ekto-Phosphorylierung des Membranproteins FAT/CD36 hemmt die Aufnahme freier Palmitinsäure durch humane Thrombozyten." Doctoral thesis, Humboldt-Universität zu Berlin, Medizinische Fakultät - Universitätsklinikum Charité, 2003. http://dx.doi.org/10.18452/14956.
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Untersucht wurde der Zusammenhang zwischen der Proteinkinase A-vermittelten Ekto-Phosphorylierung des Membranproteins FAT/CD36 [Hatmi et al. 1996] und der initialen zellulären Aufnahme langkettiger Fettsäuren. Wir zeigten einen inhibitorischen Effekt auf die initiale Palmitinsäure-Aufnahme humaner Thrombozyten unter den Bedingungen der Ekto-Phosphorylierung von FAT/CD36. Damit kann erstmalig ein Mechanismus für die kurzfristige Regulation der proteinvermittelten Aufnahme langkettiger Fettsäuren vorgeschlagen werden. Für die Bearbeitung der Fragestellung wurden die Isolation "ruhender", morphologisch und funktionell intakter humaner Thrombozyten und eine Methode zur Messung der initialen Palmitinsäure-Aufnahme etabliert. Die Kinetik der Palmitinsäure-Aufnahme humaner Thrombozyten wurde charakterisiert und bestätigt, dass ein wesentlicher Anteil der initialen Aufnahme proteinvermittelt erfolgt. Die von Hatmi und Co-Autoren beschriebene Ekto-Proteinkinase A-vermittelte, cAMP-abhängige Phosphorylierung von FAT/CD36 [Hatmi et al. 1996] konnte unter unseren experimentellen Bedingungen nachvollzogen werden. Die Ekto-Phosphorylierung von FAT/CD36 ging mit einer signifikanten Abnahme der initialen Palmitinsäure-Aufnahme einher. Die maximale Abnahme auf 72 % des Kontrollwerts wurde bei einer extrazellulären ATP-Konzentration von 0,5 nM erreicht. Der inhibitorische Effekt liess sich durch Co-Inkubation mit dem spezifischen Proteinkinase A-Inhibitorpeptid PKI 5-24 oder mit beta-gamma-ATP aufheben. Der Effekt war durch Dephosphorylierung mit Alkalischer Phosphatase vollständig reversibel. Bei extrazellulären ATP-Konzentrationen zwischen 10 pM und 15 nM war der inhibitorische Effekt der Ekto-Phosphorylierung auf die Palmitinsäure-Aufnahme signifikant. ATP-Konzentrationen über 15 nM verminderten den Effekt, bei über 5 µM ATP war kein Effekt nachzuweisen. Wir konnten ausschliessen, dass die Aufhebung durch ATP-Abbauprodukte verursacht wurde. Unsere Beobachtungen deuten auf einen regulatorischen Einfluss höherer extrazellulärer ATP-Konzentrationen, der dem inhibitorischen Effekt der Ektophosphorylierung von FAT/CD36 auf die Fettsäure-Aufnahme entgegenwirkt.We investigated the correlation between the ecto-protein kinase A-mediated phosphorylation of the membrane-associated protein FAT/CD36 [Hatmi et al. 1996] and the initial cellular long chain fatty acid uptake. Under the conditions of FAT/CD36-ecto-phosphorylation, an inhibitory effect on the initial palmitate uptake of human platelets could be shown. This is the first time that a mechanism for the short-term regulation of protein-mediated long chain fatty acid uptake can be proposed. The isolation of morphologically and functionally intact resting human platelets and a method for measuring the initial palmitate uptake were established. The kinetics of palmitate uptake by human platelets were characterised and it was shown that a substantial fraction of initial palmitate uptake is protein-mediated. The ecto-protein kinase A-mediated, cAMP-dependent phosphorylation of FAT/CD36 as described by Hatmi and co-authors could be demonstrated under our experimental conditions. The ecto-phosphorylation of FAT/CD36 was paralleled by a significant impairment of the initial palmitate uptake. Maximum inhibition was achieved at 0,5 nM extracellular ATP, when the palmitate uptake was decreased to 72 % compared to control. The inhibition of palmitate uptake was abolished by co-incubation with the specific protein kinase A inhibitor peptide PKI 5-24 or with beta-gamma-methylene-ATP, and was fully reversible upon addition of alkaline phosphatase. The inhibitory effect of the ecto-phosphorylation on the initial palmitate uptake was significant at extracellular ATP concentrations between 10 pM and 15 nM. ATP concentrations over 15 nM reduced the effect and concentrations over 5 µM completely abolished it. We could exclude that the abolishment was caused by ATP-derivates. Our data point to a regulatory influence of higher ATP concentrations, that antagonises the inhibitory effect of the ecto-phosphorylation of FAT/CD36 on the initial palmitate uptake.
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BLANC, DELPHINE. "Hydrogenation asymetrique catalysee par des complexes chiraux du ruthenium : synthese de ligands chiraux a partir de diols 1,3 optiquement purs. synthese asymetrique de gamma-butyrolactones-alpha, beta, gamma-trisubstituees : (-)-methylenelactocine, acide (-)-phaseolinique et (-)-isoavenaciolide." Paris 6, 1999. http://www.theses.fr/1999PA066062.
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Les complexes chiraux du ruthenium, prepares in situ a partir d'un precurseur commercial codru(2-methylallyl) 2, ont ete utilises pour la synthese de nouveaux ligands chiraux et de composes d'interet biologique. Ces catalyseurs se sont reveles particulierement efficaces pour l'hydrogenation asymetrique de nouveaux substrats fluores et de dicetones 1,3 symetriques. Les beta-hydroxyesters fluores, ainsi que les diols 1,3 anti sont obtenus quantitativement avec de bonnes selectivites, allant jusqu'a 99%. Les alcools optiquement purs obtenus sont des intermediaires clefs pour la synthese de produits naturels ou de ligands chiraux. L'utilisation de ces complexes du ruthenium a egalement permis de mettre en evidence l'efficacite du skewphos pour l'hydrogenation asymetrique de nombreuses cetones fonctionnalisees, dans des conditions hautement controlees de temperature et de pression. La synthese de nouveaux ligands chiraux, derives du skewphos, a ete abordee : deux diphosphines hydrocarbonees ont ete preparees, ainsi qu'un diol 1,3 anti perfluore qui pourra etre utilise pour la synthese d'un nouveau ligand fluore, derive du skewphos. Une methode generale et rapide de synthese de gamma-butyrolactones beta, gamma-disubstituees a ete mise au point. L'etape clef de cette approche est l'hydrogenation asymetrique de beta-cetoesters, associee a l'alkylation diastereoselective. Cette strategie a ete appliquee a la synthese totale de la (-)-methylenelactocine et de l'acide (-)-phaseolinique, ainsi qu'a la synthese formelle de la (-)-isoavenaciolide.
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Wan, Yang. "Synthesis of β,γ-diamino acids and their use to design new analogues of the antimicrobial peptide Gramicidin Septide antimicrobien, la Gramicidine S." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS407/document.
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Dans notre groupe, nous nous intéressons au développement de peptides contenant des acides γ-aminés. Comme d’autres peptides contenant des acides aminés non naturels, ils ont montré leur capacité à posséder des conformations stables et/ou des propriétés biologiques intéressantes. De plus, ces peptides sont généralement résistant à la protéolyse. Dans l’objectif de synthétiser des acides -diaminés sous la forme d’un seul stéréoisomère, nous avons développé une voie de synthèse reposant sur une réaction de Blaise suivie d’une réduction diastéréosélective. En appliquant cette méthode, nous avons synthétisé des acides β,γ-diaminés dérivés de la D-phénylalanine et de l’acide L-glutamique. Le premier a été utilisé pour concevoir des analogues d’un peptide antimicrobien, la gramicidine S. Comparé à la molécule parent, les analogues ont montré une cytotoxicité beaucoup moins importante pour les cellules hôtes tout en conservant une activité antibactérienne intéressante. Cette étude nous a donné de meilleures connaissances pour développer d’autres analogues de la gramicidine S ainsi que d’autres peptides antimicrobiens. Nous avons également effectué de nombreuses optimisations pour synthétiser de façon efficace des acides β,γ-diaminés cycliques à partir de l’acide L-glutamique. Les oligomères incorporant ces acides β,γ-diaminés et des acides α-aminés ont montré un fort potentiel pour l’adoption de conformations stables. Ces études vont être poursuiviesIn our group, we are interested in developing peptides containing β,γ-diamino acids . Along with many other peptides containing unnatural amino acids, they have shown the ability to possess stable conformations and/or interesting biological activities. Moreover, those peptides are usually more resistant to proteolysis. In order to synthesize stereopure γ-amino acids, we have developed a synthetic route using Blaise reaction and subsequent diastereoselective reduction as key reactions. Through applying this method, we have synthesized β,γ-diamino acids derived from D-phenylalanine and L-glutamic acid. The former β,γ-diamino acid was used for designing antimicrobial peptide gramicidin S analogues. Compared with mother molecule, the analogues exerted much less host cell cytotoxicity while remaining interesting antibacterial activity. Meanwhile, it gave us more knowledge for further developing analogues of gramicidin S as well as other antimicrobial peptides. We also paid lots of effort to efficiently synthesize cyclic β,γ-diamino acids starting from L-glutamic acid. Interestingly, when oligomers incorporating this β,γ-diamino acids and α-amino acids, they have shown the potential to adopt stable conformations. The following studies will be continuously investigated
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Pimentel, Neusa Maria Nascimento. "Avaliação da resposta imuno-inflamatória no tecido cerebral de camundongos deficientes em CRAMP submetidos a modelo de etilismo agudo." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/5/5164/tde-28092018-092046/.
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O uso de álcool está aumentando em nossa sociedade e permanece associado a inúmeros problemas sociais, econômicos e de saúde. De fato, o álcool e os problemas de saúde associados a ele exercem um impacto importante na prática médica e representam um dos maiores desafios da saúde pública. O consumo de álcool na sociedade contemporânea é geralmente aceito positivamente, dificultando o reconhecimento de certos padrões de consumo como doença. O alcoolismo é um transtorno recidivante crônico caracterizado pela ingestão compulsiva de quantidades excessivas de etanol, perda de controle em sua ingestão, comportamento inadequado e a presença de um estado emocional negativo. O consumo de quantidades nocivas de álcool resulta em danos físicos e psicológicos e o vicio é um transtorno psiquiátrico que afeta as funções executivas, causando perda de interesse em outros alvos do prazer e comportamento compulsivo de busca por drogas. O álcool interage com vários sistemas neurológicos. O presente trabalho analisou a resposta imunoinflamatória no tecido cerebral de camundongos CRAMP knockout (KO) jovens e tipo selvagem (WT) submetidos ao modelo de intoxicação alcoólica, com o objetivo de investigar o impacto de CRAMP na dependência alcoólica no adolescente. O CRAMP é um peptídeo antimicrobiano com efeitos pleotrópicos e, até onde sabemos, seu papel nunca foi investigado nesse sentido. Também analisamos a secreção de vários neuropeptídeos, proteínas e citocinas. Nossos resultados mostraram uma diferença significativa na ingestão de etanol entre os animais comparados CRAMP KO e WT, o que foi relacionado a um aumento nos níveis cerebelares de IL-1beta. Concluimos que os pepitídeos antimicrobianos podem ter um papel importante na resposta imunoinflamatória que ocorre durante o etilismo agudoThe use of alcohol is increasing in our society and remains associated with countless social, economic and health problems. In fact, alcohol and the health issues associated to its abuse exert an important impact on medical practice and represent one of the biggest challenges of public health. The consumption of alcohol in contemporary society is generally accepted positively, making certain patterns of consumption very difficult to be recognized as a disease. Alcoholism is a chronic relapsing disorder characterized by compulsive ingestion of excessive amounts of ethanol, loss of control in its intake, inappropriated behavior and the presence of a negative emotional state. The consumption of harmful amounts of alcohol results in physical and or psychological damage and addiction is a psychiatric disorder that affects the executive functions, causing loss of interest in other aspects of life and a compulsive behavior. Alcohol interacts with several neurologic systems. The present work analyzed the immuno-inflammatory response in the brain tissue of young CRAMP knockout (KO) and wild-type (WT) mice submitted to a model of alcohol intoxication, in order to investigate the impact of CRAMP in teenager alcohol addiction. CRAMP is an antimicrobial peptide with pleotropic effects and, as far as we know, its role had never been investigation in this regard. We also analysed the secretion of several neuropeptides, proteins and cytokines. Our results showed a significant difference in ethanol intake when CRAMP KO and WT animals were compared, which was related to an increase in the cerebellar levels of IL-1beta. We conclude that antimicrobial peptides may play an important role in the immunoinflammatory response that occurs during acute alcoholism
Books on the topic "Gamma-ammino acidi beta,beta-disostituiti"
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1946-, Stephens David N., ed. Anxiolytic [Beta]-carbolines: From molecular biology to the clinic. Berlin: Springer-Verlag, 1993.
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Ellis, G. P., and G. B. West. Progress in medicinal chemistry. Amsterdam: Elsevier, 1985.
Find full textBook chapters on the topic "Gamma-ammino acidi beta,beta-disostituiti"
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Pearl, Phillip L., and Lance Rodan. "Disorders of Beta and Gamma Amino Acids." In Physician's Guide to the Diagnosis, Treatment, and Follow-Up of Inherited Metabolic Diseases, 433–52. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-67727-5_24.
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Brown, Robert Andrew. "The Crucial Relevance of ALA and LA as Primary Peroxisomal Beta-Oxidation Substrates, of Oxidised LA as the Primary Endogenous Activator of PPAR Gamma, and Energy Deficit as the Primary Activator of PPAR Alpha." In Omega-3 Fatty Acids, 451–63. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-40458-5_32.
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Duvnjak, Marija, Kristina Kljak, and Darko Grbeša. "Nitrogen Storage in Crops: Case Study of Zeins in Maize." In Nitrogen in Agriculture - Physiological, Agricultural and Ecological Aspects [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.95380.
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Crop grains accumulate significant amounts of nitrogen in the form of storage proteins. Grain storage proteins are not only important in the aspects of germination but also, storage proteins are a valuable food source in human and animal nutrition. This chapter will give insight into genotype and growing conditions influencing the quantity and quality of storage proteins, primarily maize storage proteins the leading cereal by world production. Main storage proteins in cereals are prolamins, and in maize prolamins are called zeins located within the endosperm in protein agglomerations called protein bodies. Four main classes of zein proteins are: alpha, beta, gamma and delta zein. Each of four zein classes has a distinctive position and role within protein bodies. Prolamin proteins define nutritional value of maize grain not only via amino acid quality but also via starch availability. Starch, the most important energy component of maize grain, is located within starch-protein matrix. Within this matrix, starch granules are surrounded by protein bodies that limit starch availability. In this chapter, we will describe how zein proteins influence characteristics of maize grain and nutritional value of maize.
Conference papers on the topic "Gamma-ammino acidi beta,beta-disostituiti"
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Plow, E. F., G. A. Marguerie, and M. H. Ginsberg. "RECOGNITION SPECIFICITY OFADHESION RECEPTORS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643728.
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The cytoadhesins are a broadly distributedfamily of structurally, immunologicallyand functionally related cell surface molecules which participate in cellular adhesivereactions. The members of this family are heterodimeric in structure and consist of similar, if not identical, beta subunitsand related, but not identical, alpha subunits. A common functional property of the cytoadhesins is that they possess an arginyl-glycyl-aspartic acid (RGD) recognition specificity which mediates their capacity to act as receptors for adhesive proteins.The above assigned characteristics of thecytoadhesin family are based upon immunochemical analyses, primary structural determinations, deduced amino acid sequences fromcDNA clones and from dissectionof the recognition specificity of specificfamily members for their adhesive proteins.Platelet GPIIb-IIIa, the prototype of thecytoadhesin family, exhibits a very relaxed recognition specificity which permits itto interact with at least four distinct RGD-containing proteins: fibrinogen (Fg), fibronectin, von Willebrand Factor and vitronectin. RGD-containing peptidesas well as peptides corresponding in structure to the extreme carboxyl terminus of the gamma chain of Fg inhibit the binding of this adhesive protein set to GPIIb-IIIa.Both peptide sets interact with GPIIb-IIIaat either the same set of sites or intercommunicating sites. Nevertheless, using crosslinking reagents, certain RGD and gamma chain peptides can be crosslinked to different subunits of GPIIb-IIIa. This raises the possibility that a binding pocket for the adhesive proteins on GPIIb-IIIa may be directly comprised or situated in close proximity to both subunits of the cytoadhesin. Endothelial cells also express a cytoadhesin which is capable of binding Fg. Although both RGD and gamma chain peptides inhibit this interaction, the finerecognition specificity of the platelet and endothelial cell cytoadhesin for Fg are distinguishable. Thus, by combining very similar if not the same beta subunits with different alpha subunits, the RGD specificity of the cytoadhesins may bemodulated to achieve selectivity in the recognition of adhesive proteins.
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Dampf, Sara J., and Timothy M. Korter. "Low-frequency Vibrational Spectroscopy of $\gamma$-Aminobutyric Acid Derivatives: GABA Hydrochloride and $\beta$-Phenyl-GABA Hydrochloride." In 2020 45th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz). IEEE, 2020. http://dx.doi.org/10.1109/irmmw-thz46771.2020.9370844.
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Lara-Robustillo, Esperanza, and Marina Rodri´guez Alcala´. "Comparison of Actinides Separation by Coprecipitation and Chromatographic Resin (Dipex®) for Gross Alpha Determination." In ASME 2009 12th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2009. http://dx.doi.org/10.1115/icem2009-16249.
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The determination of gross alpha in wastes that have alpha, beta and gamma emitters is important from a regulatory point of view. The level of alpha radioactivity allowed is limited in a low and medium level radioactive location for safety reasons, so it is necessary to measure it with high precision. In order to quantify the concentration of alpha emitters it is necessary to perform an adequate radiochemical separation before measurement. In this paper has been studied and compared the results obtained by two separation methods: one by coprecipitation using BaSO4, Fe(OH)3 and/or CaC2O4 as precipitant agents and the other one by extraction chromatography using Actinide Resin (Dipex®). The separation procedures have been applied to spent ion exchange resins from Spanish Nuclear Power Plants. Once the sample was dissolved by acid digestion in a closed vessel microwave equipment, and the radionuclides of interest were isolated of the rest by the techniques before mentioned, the gross alpha was measured by Liquid Scintillation Counting (LSC), using the α/β discrimination if necessary (when the separation was not completed), since this technique is today one of the most used and accurate for measuring radioactivity because LS spectrometry can detect practically all types of radiation with high efficiency.
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Campodónico, Paola B., Andrea Motter, Eduardo F. Farias, Elisa D. Bal de Kier Joffé, and Laura B. Todaro. "Abstract 339: Importance of retinoic acid receptors alpha, beta and gamma on thein vivotumor growth of a murine mammary bi-cellular tumor cell line: Differential response of luminal and myoepithelial components to retinoids treatment." In Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC. American Association for Cancer Research, 2010. http://dx.doi.org/10.1158/1538-7445.am10-339.
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Denton, Mark S., and Mercouri G. Kanatzidis. "Innovative Highly Selective Removal of Cesium and Strontium Utilizing a Newly Developed Class of Inorganic Ion Specific Media." In ASME 2009 12th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2009. http://dx.doi.org/10.1115/icem2009-16221.
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Highly selective removal of Cesium and Strontium is critical for waste treatment and environmental remediation. Cesium-137 is a beta-gamma emitter and Strontium-90 is a beta emitter with respective half-lives of 30 and 29 years. Both elements are present at many nuclear sites. Cesium and Strontium can be found in wastewaters at Washington State’s Hanford Site, as well as in wastestreams of many Magnox reactor sites. Cesium and Strontium are found in the Reactor Coolant System of light water reactors at nuclear power plants. Both elements are also found in spent nuclear fuel and in high-level waste (HLW) at DOE sites. Cesium and Strontium are further major contributors to the activity and the heat load. Therefore, technologies to extract Cesium and Strontium are critical for environmental remediation waste treatment and dose minimization. Radionuclides such as Cesium-137 and Strontium-90 are key drivers of liquid waste classification at light water reactors and within the DOE tank farm complexes. The treatment, storage, and disposal of these wastes represents a major cost for nuclear power plant operators, and comprises one of the most challenging technology-driven projects for the DOE Environmental Management (EM) program. Extraction technologies to remove Cesium and Strontium have been an active field of research. Four notable extraction technologies have been developed so far for HLW: solvent extraction, prussian blue, crystalline silicotitanate (CST) and organic ion-exchangers (e.g., resorcinol formaldehyde and SuperLig). The use of one technology over another depends on the specific application. For example, the waste treatment plant (WTP) at Hanford is planning on using a highly-selective organic ion-exchange resin to remove Cesium and Strontium. Such organic ion-exchangers use molecular recognition to selectively bind to Cesium and Strontium. However, these organic ion-exchangers are synthesized using multi-step organic synthesis. The associated cost to synthesize organic ion-exchangers is prohibitive and seriously limits the scope of applications for organic ion-exchangers. Further issues include resin swelling, potential hydrogen generation and precluding final disposal by vitrification without further issues. An alternative to these issues of organic ion-exchangers is emerging. Inorganic ion-exchangers offer a superior chemical, thermal and radiation stability which is simply not achievable with organic compounds. They can be used to remove both Cesium as well as Strontium with a high level of selectivity under a broad pH range. Inorganic ion-exchangers can operate at acidic pH where protons inhibit ion exchange in alternative technologies such as CST. They can also be used at high pH which is typically found in conditions present in many nuclear waste types. For example, inorganic ion-exchangers have shown significant Strontium uptake from pH 1.9 to 14. In contrast to organic ion-exchangers, inorganic ion-exchangers are not synthesized via complex multi-step organic synthesis. Therefore, inorganic ion-exchangers are substantially more cost-effective when compared to organic ion-exchangers as well as CST. Selective removal of specified isotopes through ion exchange is a common and proven treatment method for liquid waste, yet various aspects of existing technologies leave room for improvement with respect to both cost and effectiveness. We demonstrate a novel class of inorganic ion-exchangers for the selective removal of cesium and strontium (with future work planned for uranium removal), the first of a growing family of patent-pending, potentially elutable, and paramagnetic ion-exchange materials [1]. These highly selective inorganic ion-exchangers display strong chemical, thermal and radiation stability, and can be readily synthesized from low-cost materials, making them a promising alternative to organic ion-exchange resins and crystalline silicotitanate (CST). By nature, these inorganic media lend themselves more readily to volume reduction (VR) by vitrification without the issues faced with organic resins. In fact, with a simple melting of the KMS-1 media at 650–670 deg. C (i.e., well below the volatilization temperature of Cs, Sr, Mn, Fe, Sb, etc.), a VR of 4:1 was achieved. With true pyrolysis at higher temperatures or by vitrification, this VR would be much higher. The introduction of this new family of highly specific ion-exchange agents has potential to both reduce the cost of waste processing, and enable improved waste-classification management in both nuclear power plants (for the separation of Class A from B/C wastes) and DOE tank farms [for the separation of low level waste (LLW) from high level waste (HLW)]. In conclusion, we demonstrate for the first time a novel inorganic ion-exchanger for the selective removal of Cesium and Strontium. These inorganic ion-exchangers are chemical, thermal and radiation stable. These inorganic ion-exchangers can be synthesized in a cost-effective way which makes them significantly more effective than organic ion-exchange resin and CST. Finally, new thermal options are afforded for their final volume reduction, storage and disposal.