Liver glutamic-oxalacetic

M16. Molander, D. W., Graver, L. F., and Packs, G. T., Liver enzymes, serum glutamic oxalacetic transminase, cholinesterase and alkaline phosphatase in primary and metastatic hepatic neoplasia. Acta Unio Int. Cancrum 16, 1478-1481 (1960). 

Aminooxyacetate, an inhibitor of glutamate— oxalacetate transaminase, inhibits the formation of aspartate. Soling Kleinicke (1976) observed that aminooxyacetate did not inhibit the formation of glucose from lactate and, therefore, concluded that the malate-aspartate shuttle was not essential for the lactate gluconeogenesis in avian liver. However, Ochs Harris (1980) found that aminooxyacetate did block lactate gluconeogenesis when lower concentrations of pyruvate were used and incubation was for longer than 15 min. They concluded that the malate-aspartate shuttle was required. 

Fig. 12.41. Differentiation of fresh liver (1) from frozen and thawed liver (2) by electrophoretic separation of glutamate-oxalacetate transaminases (a) GOT sarcoplasm, (b) GOT mitochondria (according to Hamm 2indMasic, 1975)...

Injection of hydrocortisone into the rat results in an approximately four fold increase in liver (but not kidney) tyrosine-a-ketoglutarate transaminase activity 374)- Corticosterone and cortisone were somewhat less effective. Interesting in this connection is the observation that injection of L-tyrosine increased the activity of tyrosine-a-ketoglutarate transaminase to about the same extent as hydrocortisone. Other amino acids had a much smaller stimulating effect which was attributed to adrenal cortical stress. In a preliminary report the addition of hydrocortisone to lymphocyte suspensions was found to inhibit glutamic-oxalacetic transaminase activity 376). 

Aspartate aminotransferase (most active in liver) Aspartate + Oxoglutarate (a-kitoglutarate) Oxalacetate + Glutamate... 

Ti-Aspartic Oxidase. Aspartase and transaminases account for a major part of the metabolism of L-aspartic acid. n-Aspartic acid is oxidized by an enzyme present in liver and kidney. This is an oxidase that converts aspartate to oxalacetate and ammonia while reducing oxygen to hydrogen peroxide. The oxidase was resolved by ammonium sulfate precipitation and dialysis to a protein that could be reactivated by FAD but not by FMN. The enzyme differs from n-amino acid oxidase in its insensitivity to benzoate. The only other known substrate for the partially purified D-aspartic oxidase is D-glutamate, but since the relative rates of oxidation of the two amino acids vary during the preparation of the enzyme, it is... 

D-Aspariic Acid Oxidase. Still et al. reported that rabbit kidney and liver contain a soluble enzyme which catalyzes the aerobic oxidation of D-aspartate to oxalacetate plus NH3 with the formation of hydrogen peroxide. In a later study by Still and Sperling the D-aspartic acid oxidase was resolved and reactivated by the addition of FAD. The purified enzyme showed about one-sixth the activity with D-glutamate this, according to these workers, is best explained by the presence of a D-glu-tamic acid oxidase. The activity of n-aspartic acid oxidase is higher than that of D-amino acid oxidase in rabbit kidney and liver, and they are of the same order of activity in pig kidney. In contrast to pig kidney o-amino acid oxidase, which is inhibited by benzoic acid, the D-aspartic acid oxidase was unaffected. 

In the presence of ammonium chloride, the production of ketone bodies is increased in rat liver homogenates and slices, slices of brain, and possibly in guinea pig kidney cortex. Rat liver slices seem to exhibit this effect only when prepared from well-fed animals. The extra ketosis results from a decrease in oxalacetate brought about by the conversion of a-ketoglutarate to glutamic acid in the presence of the added ammonium ion. ... 

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