Nonenzymatic glycosylation of peripheral nerve protein in diabetes mellitus.

Abstract

A new affinity chromatography system that selectively retains glycosylated amino acids was utilized to determine the amount of nonenzymatic glycosylation present in peripheral nerve from diabetic and control rats and dogs. The mean value for glycosylated amino acids in diabetic rats was 2.8 times greater than the mean value in normal rats (P < 0.001). In diabetic dogs, mean values were 2.15 times greater than normal values (P < 0.05). Amino acid analysis of reduced, glycosylated amino acids previously isolated by affinity chromatography showed that glycosylated Lys and its hydrolysis rearrangement products were the major borohydride-reducible adduct present. Another glycosylated product was present in major proportions. This radioactive product did not chromatograph with any of the available glycosylated amino acid standards. The finding that diabetes results in a nearly 3-fold increase of peripheral nerve glycosylation is consistent with a number of previous investigations in which glycosylation was measured in Hb, serum albumin and urinary amino acids and peptides from diabetics and normals. Increased nonenzymatic glycosylation evidently is occurring in a tissue where physiological, morphological and clinical degeneration characteristically develop as a result of diabetes mellitus.