Serum gamma-glutamyltransferase isoenzymes in extrahepatic biliary obstruction.

The gamma-glutamyltransferase isoenzymes in the sera of patients with extrahepatic biliary obstruction have been studied, using electrophoretic, gel filtration, and ultracentrifugation techniques, and compared with those present in normal sera. Five isoenzymes were shown to exist in patients' sera, three of which were not demonstrated in normal sera. The observations are discussed in relation to the influence of biliary regurgitation and the possible solubilisation of membrane-bound enzymes. The results are compared with those of previous studies on alkaline phosphatase.