STUDIES ON AROMATIC AMINO-ACID OXIDASE ACTIVITY IN RAM SPERMATOZOA - ROLE OF PYRUVATE AS AN ANTIOXIDANT

Chemical antioxidants and catalase have been shown to be ineffective i n improving the motility of ram spermatozoa in a chemically-defined di luent (RSD-1). In an attempt to identify the biochemical basis of this observation, the activity of aromatic amino acid oxidase (AAAO), the enzyme responsible for generation of hydrogen peroxide in ram and bull spermatozoa, has been investigated. Ram spermatozoa contained higher levels of AAAO activity than bull spermatozoa, although the physico-ch emical properties of the enzyme were generally similar in both species . Components of the medium had a marked effect upon AAAO activity. In the presence of glutamate and 3-( N-morpholino)propanesulfonic acid (M OPS), AAAO activity was decreased. Pyruvate appeared to increase AAAO activity. This was due to the ability of this substance to destroy hyd rogen peroxide. Pyruvate in RSD-1 works as an effective antioxidant an d therefore eliminates the need for other antioxidants in the semen di luent. (C) 1998 Elsevier Science B.V. All rights reserved.