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Abstract
Summary: The most active carboxylating enzyme in cell-free extracts of Neocosmospora vasinfecta was identified as pyruvate carboxylase (EC 6.4.1.1) on the basis of its substrate specificity, biotin dependence and cofactor requirements. Following 48 h. growth on acetate as sole carbon source, the specific activity of the extracted enzyme was 1·4 to 3 times greater than when the organism was maintained on glucose. Bicarbonate fixation in vivo was considerably reduced in the acetategrown mycelium, but was enhanced when ethyl pyruvate was supplied. The mycelial pyruvic acid content was almost an order of magnitude lower in acetategrown mycelium than in glucose-grown. These results indicate that bicarbonate fixation in acetate-grown mycelium may be limited by the availability of pyruvic acid.
- Accepted:
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