Glycation of amino groups in protein. Studies on the specificity of modification of RNase by glucose.

摘要: Ribonuclease A has been used as a model protein for studying the specificity of glycation amino groups in under physiological conditions (phosphate buffer, pH 7.4, 37 degrees C). Incubation RNase with glucose led to an enhanced rate inactivation enzyme relative modification lysine residues, suggesting preferential active site residues. Sites were identified by acid analysis tryptic peptides isolated reverse-phase high pressure liquid chromatography and phenylboronate affinity chromatography. Schiff base adducts trapped Na-BH3CN alpha-amino group Lys-1 was primary (80-90%) initial formation on RNase. In contrast, Lys-41 Lys-7 accounted about 38 29%, respectively, ketoamine formed via Amadori rearrangement. Other sites reactive included N alpha-Lys-1 (15%), epsilon-Lys-1 (9%), Lys-37 (9%) which are adjacent acidic acids. The remaining six residues RNase, located surface protein, relatively inactive forming either or adduct. Both equilibrium concentration rearrangement at each found be important determining