Oxalacetic decarboxylase

Creighton and Rose (45) have explored the route shown in Scheme 7 to synthesize chiral pyruvate. The method takes advantage of the fact that pyruvate kinase decarboxylates oxalacetate with retention of configuration. The requisite labeled oxalacetates were prepared as shown from the appropriately labeled L-malates, available from equilibration with fumarase in either deuterated or tritiated water. This method is convenient for the preparation of small amounts of chiral acetate but suffers from the low oxalacetate decarboxylase activity of pyruvate kinase. 

In chloroplasts oxalacetic acid could be reduceo to malic acid (by NADP-malate dehydrogenase) and this acid could be decarboxylated and will regenerate the substrate for PEPCase. Another reaction is also possible - oxalacetic acid to be directly decarboxylated by oxalacetate decarboxylase. In either case the decarboxylase reactions will strengthen the flow of CO2 to RuBPCase and will contribute to the better operation of Calvin cycle. 

Phosphopyruvaie Carboxylases. In addition to the malic enzyme, other oxalacetic decarboxylases are known. Enzymes purified from various... 

Nickel is an activator of a number of enzymes, e. g., alkaline phosphatase and oxalacetate decarboxylase, which can also be activated by other divalent metal ions. Nickel also enhances insulin activity. The essential role of nickel has been established by inducing deficiency S5nnptoms in feeding experiments with chickens and rats. These symptoms include changes in the liver mitochondria. The daily intake in food amounts to 150-700 pg. The nickel requirement is estimated to be 35-500 pg/day. 

The PCK of A. succinidproducens requires the nucleoside triphosphate ADP, and a pyruvate kinase-like activity of this enzyme was identified. In gluconeogenesis, PCK catalyzes the irreversible decarboxylation of oxalacetate, and in A. succinici-producens, AMP was shown to activate this oxalacetate decarboxylase reaction (Jabalquinto et al. 1999). 

Assay of Transamination. Since the sum of keto acids and amino acids does not change in a transamination, specific reactions are required to assay the reaction products. Some of the methods used are oxidation of a-ketoglutarate to succinate and determination of succinate with succinic dehydrogenase decarboxylation of oxalacetate with aniline citrate decarboxylation with specific amino acid decarboxylases separation of products on paper chromatograms and spectrophotometric determination of those keto acids that exhibit specific absorption. 

Enzymes, apparently unrelated to the malic enzyme or to Utter s oxalacetic carboxylase, catalyzing the decarbmqrlation of oxalacetate, are present in bacteria and certain plant tissues. Some of these enzymes, including the highly purified oxalacetic carboxylase (decarboxylase) of Microeoceus lysodeikticm (152), can catalyze an incorporation of CO in oxalacetate which does not require ATP (236) the mechanism of this incorporation is unknown. Kalten-bach and Kalnitsky (198,199) have reported a net synthesis of oxal-... 

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