Diabetes, Vol 37, Issue 8 1144-1150, Copyright © 1988 by American Diabetes Association
Nonenzymatic glycation of basement membranes from human glomeruli and bovine sources. Effect of diabetes and age
RL Garlick, HF Bunn and RG Spiro
Department of Medicine, Harvard Medical School, Boston, Massachusetts.
The nonenzymatic glycation of glomerular basement membranes (GBMs) from 14
diabetic and 19 nondiabetic human subjects was determined after boronic
acid affinity and high-performance cation-exchange chromatography of their
NaB[3H]4-reduced ketoamine adducts. The glucitol-lysine (Glc-Lys) and the
glucitol-hydroxylysine (Glc-Hyl) content of diabetic GBM was found to be
about twofold higher than that of nondiabetic samples (P less than .001).
The content of these glycated amino acids did not correlate with age over
the range examined (20-91 yr) or with the length of disease in diabetic
subjects (2-16 yr). However, analyses of Glc-Lys and Glc-Hyl in calf and
adult bovine GBM and lens capsules indicated that the levels of these
glycated amino acids were several times greater in basement membranes from
older animals. We also observed that guanidine-insoluble collagen of bovine
GBM is more extensively glycated (approximately 4-fold) than primarily
noncollagenous proteins that are extracted by this reagent. In all of the
basement membranes examined, the percentage of glycation of lysine was
greater than of hydroxylysine. Characterization of the components released
by alkaline hydrolysis indicated that O-glycosylated hydroxylysine residues
are nonenzymatically N-glycated to the same extent as those without an
enzymatically attached carbohydrate unit. Our study indicates that more
than a hundred times as many hydroxylysine residues are enzymatically
glycosylated in human and bovine GBM as those containing the
nonenzymatically formed ketoamine adduct.