Developmental changes in gamma-glutamyl transpeptidase in human amniotic fluid.

Human amniotic fluid gamma-glutamyl transpeptidase (GGT) occurs in a high molecular weight form, as shown by G-200 gel chromatography. Papain treatment causes the formation of a GGT molecule with an approximate molecular weight of 98 000. Early amniotic fluid contains GGT which binds mostly to Con A-Sepharose and shows alpha-mobility on cellulose acetate electrophoresis. In late amniotic fluid, the major portion of the GGT activity is concanavalin A-nonreactive and is present in the beta-region on electrophoresis. Neuraminidase treatment abolishes the difference in the electrophoretic mobility between early and late amniotic fluid GGT. Papain treatment has no effect on the electrophoretic mobility or concanavalin A-binding of GGT. The results suggest that the carbohydrate moiety of amniotic fluid GGT undergoes developmental changes during gestation.