Characterization of the oligosaccharides of plasma sex hormone binding globulin from noncirrhotic alcoholic patients

In previous reports we have demonstrated high plasma levels of sex hormone- binding globulin (SHBG) in asymptomatic alcoholic men. In the present work the physicochemical properties of SHBG from plasma of noncirrhotic alcoholi c patients have been further compared with SHBG of control subjects. Steroi d binding to SHBG was similar for tilt: two groups: alcoholic men, K-d of 0 .62 +/- 0.07 nM and control individuals, K-d of 0.70 +/- 0.10 nM. The struc ture of oligosaccharides attached to SHBG from controls and alcoholic men w ere determined by using serial chromatography. Our data indicated that 7% o f SHBG of control individuals was not retarded by the Con-A column, whereas similar to 30% of SHBG of alcoholic men eluted in the void Volume of Con A . Approximately 46% of SHBG of alcoholics applied to Con A, possessed biant ennary complex oligosaccharides, as indicated by the fact that it could be eluted with methyl-alpha-D-glucopyranoside and by its retention on wheat ge rm agglutinin; in contrast, when SHBG from control men was analyzed, simila r to 51% was eluted with methyl-alpha-D-glucopyranoside. Approximately 9% o f the biantennary complex oligosaccharides on SHBG of control men and none of those on SHBG from alcoholic men were fucosylated on the chitobiose core , as determined by chromatography on Lenn culinaris lectin. Galactosylated oligosaccharides were also present on the SHBG fraction as indicated by its interaction with Ricinus communis-I. Approximately 24% of SHBG of alcoholi c men and 39% of those on SHBG from control individuals applied to Con-A we re retained and could be eluted with methyl-alpha-D-mannopyranoside. Eviden ce based on the binding on mannoside-eluted SHBG to Con-A, wheat germ agglu tinin, and R. communis-I indicated that at least the SHBG in this fraction, from alcoholics or controls, contained two glycosylation sites and that th e sites were differentially glycosylated. (C) 2000 Elsevier Science Inc. Al l rights reserved.