The Krebs (or
tricarboxylic acid, TCA) cycle forms a central junction in aerobic metabolism,being connectedto glycolysis, gluconeogenesis, fatty acid metabolism and amino
acid metabolism.
Pyruvate carboxylase (PC)
catalyzes the carboxylation of pyruvate to form oxaloacetate, an important
so-called anaplerotic reaction to provide a sufficient level of metabolites for
the TCA cycle. The breakdown of oxaloacetate to pyruvate by oxaloacetate
decarboxylases (ODx) is mainly known from prokaryotic organisms where two main
variants of ODx enzymes are known: a membrane-bound variant that depends on
sodium and biotin and a soluble variant that depends on divalent cations. Far
less is known about ODx activity in mammalian organisms, apart from the
promiscuous activity of some metabolic enzymes.
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