Evaluation of serum gamma-glutamyltransferase by electrofocusing, and variations in isoform patterns.
Serum gamma-glutamyltransferase (EC 2.3.2.2) showed microheterogeneity on electrofocusing, owing to variations in sialic acid content. We investigated the isoform patterns of papain-treated serum samples on agarose gels containing nonionic detergent and ampholytes in the low pH range. Serum from cases of cholestasis show seven bands with gamma-glutamyltransferase activity. These same bands were also found in liver tissue similarly treated, and they had pl values ranging from 3.8 to 4.2. Papain-treated sera that also had been neuraminidase digested showed only a single band, still enzymatically active and with a pl of 5.9. Increased gamma-glutamyltransferase in serum as a result of alcohol abuse was combined with a abnormally high degree of sialylation of the enzyme, giving more anodal isoforms. The decline in the concentration of this enzyme during several weeks of abstinence was accompanied by a gradual decrease in gamma-glutamyltransferase sialyation and the appearance of more cathodal fractions.
D000328:Adult; D000437:Alcoholism / Q000097:blood*; D006801:Humans; D007525:Isoelectric Focusing; D008099:Liver / Q000201:enzymology; D008297:Male; D008875:Middle Aged; D009439:Neuraminidase; D010206:Papain; D005723:gamma-Glutamyltransferase / Q000097:blood* / Q000302:isolation & purification
D005723:gamma-Glutamyltransferase; D009439:Neuraminidase; D010206:Papain