Different effects of reductive and nonreductive glucosylation on LDL-catabolism

The effects of various degrees of reductive and nonreductive glucosylation of low density lipoprotein on its catabolism by human fibroblasts have been examined. Moderate glucosylation of LDL does not alter its interaction with the high affinity receptor at concentrations of 5-2000 micrograms LDL-cholesterol/ml. Only heavy glucosylation of LDL (more than 12 lysine residues glucosylated per apo B), i.e. conditions not expected to occur in diabetes, slows receptor-mediated internalisation and degradation. In contrast, impairment of LDL-catabolism has been found at even low degrees of reductive glucosylation. The possible reasons for the different properties of reductively and nonreductively glucosylated LDL are discussed.