γ-Glutamyltransferase bound to prostatic subcellular organelles and in free form in human seminal plasma

Abstract

Most of the γ-glutamyltransferase occurring in semen was found to be bound to the membranes of prostatic organelles, as is the case with Mg⁺⁺-Ca⁺⁺-dependent ATPase, and Zn⁺⁺-dependent peptidase hydrolysing succinyl (alanine)₃-paranitroanilide. Organelie-bound γ-glutamyltransferase was released in a water-soluble form by papain. Charge shift electrophoresis revealed the presence in seminal fluid of a small additional amount of γ-glutamyltransferase that is unbound and water-soluble, but also of prostatic origin. After papain treatment there was no sign of the organelle-bound Zn⁺⁺-dependent peptidase activity, nor of the Mg⁺⁺-Ca⁺⁺ dependent ATPase activity, both having been inactivated by the papain. Both organelle-bound γ-glutamyltransferase and Zn⁺⁺-dependent peptidase could be rendered soluble in active form with the non-ionic detergent Triton X-100.

Key Words:

• adenosine triphosphatase
• γ-glutamyl transpeptidase
• membrane-bound proteins
• peptidohydrolase
• prostate
• semen