Document Detail


Analysis of dynamics and mechanism of ligand binding to Artocarpus integrifolia agglutinin. A 13C and 19F NMR study.
MedLine Citation:
PMID:  3170566     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Binding of 13C-labeled N-acetylgalactosamine (13C-GalNAc) and N-trifluoroacetylgalactosamine (19F-GalNAc) to Artocarpus integrifolia agglutinin has been studied using 13C and 19F nuclear magnetic resonance spectroscopy, respectively. Binding of these saccharides resulted in broadening of the resonances, and no change in chemical shift was observed, suggesting that the alpha- and beta-anomers of 13C-GalNAc and 19F-GalNAc experience a magnetically equivalent environment in the lectin combining site. The alpha- and beta-anomers of 13C-GalNAc and 19F-GalNAc were found to be in slow exchange between free and protein bound states. Binding of 13C-GalNAc was studied as a function of temperature. From the temperature dependence of the line broadening, the thermodynamic and kinetic parameters were evaluated. The association rate constants obtained for the alpha-anomers of 13C-GalNAc and 19F-GalNAc (k+1 = 1.01 x 10(5) M-1.s-1 and 0.698 x 10(5) M-1.s-1, respectively) are in close agreement with those obtained for the corresponding beta-anomers (k+1 = 0.95 x 10(5) M-1.s-1 and 0.65 x 10(5) M-1.s-1, respectively), suggesting that the two anomers bind to the lectin by a similar mechanism. In addition these values are several orders of magnitude slower than those obtained for diffusion controlled processes. The dissociation rate constants obtained are 49.9, 56.9, 42, and 43 s-1, respectively, for the alpha- and beta-anomers of 13C-GalNAc and 19F-GalNAc. A two-step mechanism has been proposed for the interaction of 13C-GalNAc and 19F-GalNAc with A. integrifolia lectin in view of the slow association rates and high activation entropies. The thermodynamic parameters obtained for the association and dissociation reactions suggest that the binding process is entropically favored and that there is a small enthalpic contribution.
Authors:
M V Krishna Sastry; M J Swamy; A Surolia
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  263     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  1988 Oct 
Date Detail:
Created Date:  1988-11-10     Completed Date:  1988-11-10     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  14826-31     Citation Subset:  IM    
Affiliation:
Molecular Biophysics Unit, U. G. C. Centre of Advanced Studies, Indian Institute of Science, Bangalore.
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MeSH Terms
Descriptor/Qualifier:
Acetylgalactosamine / metabolism*
Carbon Isotopes
Fluorine
Galactosamine / analogs & derivatives*,  metabolism
Kinetics
Lectins / metabolism*
Ligands
Magnetic Resonance Spectroscopy / methods
Mathematics
Models, Theoretical
Plant Lectins*
Protein Binding
Chemical
Reg. No./Substance:
0/Carbon Isotopes; 0/Lectins; 0/Ligands; 0/Plant Lectins; 0/jacalin; 117766-36-6/N-trifluoroacetylgalactosamine; 31022-50-1/Acetylgalactosamine; 7535-00-4/Galactosamine; 7782-41-4/Fluorine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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