Distribution of Transaminases (Aminotransferases) in the Tissues of Pacific Salmon (Oncorhynchus), with Emphasis on the Properties and Diagnostic Use of Glutamic-Oxalacetic Transaminase

Abstract

A partially purified glutamic-oxalacetic transaminase (GOT) from salmon liver was shown likely to function best at a pH > 7.5, to be specific for the L isomer of aspartic acid, and to require pyridoxal phosphate for activity. The coenzyme appeared to be tightly bound to the apoenzyme.A survey of the scope of apparent transaminations in dialyzed homogenates of brain, heart, kidney, liver, and muscle indicated that GOT and glutamic-pyruvic transaminase were active in all tissues and that α-ketoglutarate (α-KG) was a more widely used amino acceptor than pyruvate. No transamination to the amino acceptors α-KG or pyruvate could be detected using as donors β-alanine, D-alanine, γ-aminobutyrate, glycine, histidine, proline, serine, or threonine. The following amino acids showed various degrees of transamination with α-KG in at least some tissue homogenates: L-leucine, L-norvaline, L-ornithine, L-phenylalanine, L-tyrosine, and L-valine. Interpretation of these results is discussed, particularly in relation to comparative biochemistry.Spectrophotometric estimations of plasma or serum GOT levels were used to distinguish at a significant level (p < 0.01), apparently healthy fish from those treated with the hepatic poisons bromobenzene and CCl4or those affected by bacterial kidney disease. The practical value of using GOT estimations as a diagnostic tool is discussed.It is tentatively suggested from limited data that the activity (units of enzyme/milligram tissue N) of GOT in various tissues decreases in the following order: heart, liver, kidney, and muscle.