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Transaminase Activity in Sheep Rumen Content

Faculty of Agriculture, Mie University, Tsu, Japan

ABSTRACT

Transaminase activities of sheep rumen were studied. The protozoa-rich fraction showed active transaminase activities. In this fraction nine amino acids, alanine, valine, leucine, isoleucine, phenylalanine, aspartic acid, cysteine, serine, and methionine, showed some activity in transaminating with -ketoglutaric acid. Transaminase activities were demonstrated also in the bacterial fraction in which alanine, phenylalanine, valine, leucine, isoleucine, and aspartic acid were utilized as amino donors to form glutamic acid. The cell-free soluble fraction of rumen fluid had no glutamic-pyruvic transaminase activity.

The glutamic-pyruvic transaminase in the protozoa-rich fraction catalyzed the reaction that alanine transaminated with -keto-glutarate to form glutamic acid and pyruvic acid in equal molar concentrations. Glutamic-pyruvic transaminase activity was proportional to the protein concentration of the crude enzyme preparation. The optimum temperature of the reaction was about 37 C; at 60 C the enzyme was still active. When the preparation was heated at 100 C for ten minutes, the activity was completely eliminated. The optimum pH was in the range of pH 6.0 to 7.0. Dialysis for 70 hr resulted in some loss of activity but which could be restored completely by the addition of pyridoxal phosphate. Addition of either p-chloromercuribenzoic acid or HgCl₂ completely inhibited the glutamic-pyruvic transaminase activity. Glutathione reduced the inhibition induced by addition of PCMB.