Nonenzymatic glycosylation of human IgG: in vitro preparation.
Incubation of human serum with either D- (1-14C) galactose (5 mM), D- (1-14C) glucose (5 mM) or L- (1-14C) fucose (5 mM) in vitro for 7 days under physiological conditions resulted in the accumulation of radioactivity into trichloroacetic acid precipitable material. Separation of the serum proteins by Sephadex G-200 chromatography, revealed the association of radioactivity with the albumin fraction (95%) and to a lesser extent with IgG (4%) and IgM (1%). D-galactose glycosylated purified human IgG at 2 to 3 fold the rate of D-glucose of L-fucose. The rate of glycose incorporation into IgG increased parabolically with increasing pH and temperature of incubation, and followed a first order dependence with either the glycose or the IgG concentration. The post-translational modification of IgG through nonenzymatic glycosylation may affect its immunological properties in clinical conditions associated with increased blood sugar concentrations.
D002384:Catalysis; D002474:Cell-Free System; D005643:Fucose; D005690:Galactose; D005947:Glucose; D006023:Glycoproteins; D006801:Humans; D007074:Immunoglobulin G; D013696:Temperature; D013997:Time Factors
D006023:Glycoproteins; D007074:Immunoglobulin G; D005643:Fucose; D005947:Glucose; D005690:Galactose