The role of alpha- and epsilon-amino groups in the glycation-mediated cross-linking of gammaB-crystallin. Study of three site-directed mutants.
Abstract
In the previous report we demonstrated that gammaB-crystallin is glycated predominantly at the N-terminal alpha-amino group (Casey, E. B., Zhao, H. R., and Abraham, E. C. (1995) J. Biol. Chem. 270, 20781-20786). To investigate the possible role of alpha- and epsilon-amino groups of gammaB-crystallin in glycation-mediated cross-linking, Lys-2 or Lys-163, or both, were mutated to threonine by site-directed mutagenesis in bovine gammaB-crystallin cDNA. Wild type and mutant gammaB-crystallins were expressed in Escherichia coli cells. Cross-linking studies were performed by incubating wild type and mutant gammaB-crystallins with glyceraldehyde, ribose, and galactose followed by SDS-polyacrylamide gel electrophoresis under reducing conditions. When both of the lysines of gammaB-crystallin were mutated to threonines (gammaB-K2T/K163T), the quantity of cross-linked products was greatly reduced, indicating that, despite the fact that the alpha-amino group is a major glycated site, epsilon-amino groups play a predominant role in cross-linking. Therefore, cross-linking ability depends not only upon the level of glycation but also upon which amino group is glycated. Steric hindrance may decrease the cross-linking ability of the alpha-amino...Continue Reading
References
Pentosidine: a molecular marker for the cumulative damage to proteins in diabetes, aging, and uremia
Citations
Related Concepts
Related Feeds
ASBMB Publications
The American Society for Biochemistry and Molecular Biology (ASBMB) includes the Journal of Biological Chemistry, Molecular & Cellular Proteomics, and the Journal of Lipid Research. Discover the latest research from ASBMB here.