MASSIVE GLYCATION OF PROTEIN HC, A LOW-MOLECULAR-WEIGHT LIPOCALIN, INNONDIABETIC INDIVIDUALS

Human protein HC is a member of the lipocalin superfamily with unique properties since it carries a covalently bound fluorescent chromophore mediating the linkage of the major part of protein HC to several plas ma proteins, with IgA as the dominating complex partner, Native protei n HC displays characteristic absorption and fluorescence spectra simil ar to those of glycated proteins with advanced glycosylation end produ cts (AGEs), In vitro glycation of protein HC induces the formation of fibril aggregates with a corresponding increase of absorption in the v isible region of the spectrum, Boronate-affinity chromatography and a novel galactosyltransferase assay indicate that protein HC is modified ,vith residues of glucose exposed in a terminal non-reducing position which is typical of glycated proteins, The glycation level of several isolated batches of protein HC as measured by both assays was around 3 5%, which represents the highest level described for human plasma-deri ved proteins from healthy individuals. (C) 1997 Federation of European Biochemical Societies.