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Galactose Residue (galactose + residue)
Selected AbstractsC-Disaccharides as Probes for Carbohydrate Recognition , Investigation of the Conformational Requirements for Binding of Disaccharide Mimetics of Sialyl Lewis XEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2007Richard W. Denton Abstract A set of C-disaccharide analogs was designed to probe the recognition of a known O-disaccharide mimetic of sialyl Lewis X, to P-selectin. The synthesis of the C-glycosides centered on the de novo construction of the galactose residue via an oxocarbenium ion/enol ether cyclization. Conformational analysis was performed by a combination of NMR spectroscopy and molecular mechanics (MM) and molecular dynamics (MD) calculations. The inhibition of P-selectin binding was evaluated in a P-selectin Biacore assay. At 12 mM, the O-glycoside showed 48,% inhibition of binding, while the C-glycoside analogs exhibited between 25,31,% inhibition. This data is discussed within the context of the active conformation of sLex and the conformational behavior of these ligands. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] The effect of heavy atoms on the conformation of the active-site polypeptide loop in human ABO(H) blood-group glycosyltransferase BACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2007James A. Letts The human ABO(H) blood-group antigens are oligosaccharide structures that are expressed on erythrocyte and other cell surfaces. The terminal carbohydrate residue differs between the blood types and determines the immune reactivity of this antigen. Individuals with blood type A have a terminal N -acetylgalactosamine residue and those with blood type B have a terminal galactose residue. The attachment of these terminal carbohydrates are catalyzed by two different glycosyltransferases: an ,(1,3)N -acetylgalactosaminyltransferase (GTA) and an ,(1,3)galactosyltransferase (GTB) for blood types A and B, respectively. GTA and GTB are homologous enzymes that differ in only four of 354 amino-acid residues (Arg/Gly176, Gly/Ser235, Leu/Met266 and Gly/Ala268 in GTA and GTB, respectively). Diffraction-quality crystals of GTA and GTB have previously been grown from as little as 10,mg,ml,1 stock solutions in the presence of Hg, while diffraction-quality crystals of the native enzymes require much higher concentrations of protein. The structure of a single mutant C209A has been determined in the presence and absence of heavy atoms and reveals that when mercury is complexed with Cys209 it forces a significant level of disorder in a polypeptide loop (amino acids 179,195) that is known to cover the active site of the enzyme. The observation that the more highly disordered structure is more amenable to crystallization is surprising and the derivative provides insight into the mobility of this polypeptide loop compared with homologous enzymes. [source] Design and in vitro Biodegradation of Novel Hepatocyte-Targetable (Galactose Polycation/Hemoglobin) Multilayers and MicrocapsulesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 12 2009Fu Zhang Abstract The formation of novel hepatocyte-targetable and biodegradable polycation/protein multilayers and hollow microcapsules by LbL assembly is reported, in which galactose residues allow for targetability and Hb acts as a main degradable component. The in vitro biodegradability of multilayers via proteases was evaluated in detail on both planar substrates and CaCO3 particles followed by UV-Vis, SEM, and AFM characterizations. The degradation approximately follows an exponential decay, and the relation between the kinetic constant k and the number n of deposited bilayers is well approximated by a power equation. Sustained release of the encapsulated model drug was attained by using enzymatic degradation of hollow capsules. [source] How Post-Translational Modifications Influence Amyloid Formation: A Systematic Study of Phosphorylation and Glycosylation in Model PeptidesCHEMISTRY - A EUROPEAN JOURNAL, Issue 26 2010Malgorzata Broncel Abstract A reciprocal relationship between phosphorylation and O-glycosylation has been reported for many cellular processes and human diseases. The accumulated evidence points to the significant role these post-translational modifications play in aggregation and fibril formation. Simplified peptide model systems provide a means for investigating the molecular changes associated with protein aggregation. In this study, by using an amyloid-forming model peptide, we show that phosphorylation and glycosylation can affect folding and aggregation kinetics differently. Incorporation of phosphoserines, regardless of their quantity and position, turned out to be most efficient in preventing amyloid formation, whereas O-glycosylation has a more subtle effect. The introduction of a single ,-galactose does not change the folding behavior of the model peptide, but does alter the aggregation kinetics in a site-specific manner. The presence of multiple galactose residues has an effect similar to that of phosphorylation. [source] | ||||||||||