Reaction of antibody with gamma-glutamyl transpeptidase. I. Isolation of the human enzyme and inhibition of its activity by antiserum.

Use of a four-step method of purification from human kidneys yielded gamma-glutamyl transpeptidase with specific activity 330 times higher than activity in the homogenate. The enzyme from human liver was also purified, and from urine two fractions of it were separated. From rabbits immunized with the enzyme from human kidney, antiserum was obtained which inhibits and precipitates the human-derived enzyme, and in a low degree the enzyme purified from bovine kidneys. This inhibition was independent of incubation time and precipitate formation, but dependent on the amount of antiserum used. A gamma-glutamyl transpeptidase complex with antibody was isolated on a column with CM-cellulose with electrophoretic mobility different from that of the native enzyme.