A modified assay system for collagen glucosyltransferase.

A simplified assay procedure has been developed for the determination of collagen glucosyltransferase activity in tissue extracts. Using degraded gelatine as acceptor it was possible to isolate the reaction product by precipitation on to a glass fibre disc. Under our conditions degraded gelatine is glucosylated with a reaction rate which is 3--4 times lower compared with the glucosylation of basement membrane derived glycopeptides. Good reproducibility is demonstrated by the coefficient of variation of 4% in the same assay and an interassay variation coefficient below 8%. As the assay allows the testing of large numbers of samples in a few hours, it should prove a useful tool to determine the enzyme level in the tissue of diabetic animals. In humans the activity of the glucosyltransferase could provide a biochemical parameter related to diabetic microangiopathy.