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histidine decarboxylase, pyruvoyl type This enzyme converts histadine to histamine in a single step by catalyzing the release of CO2. This type is synthesized as an inactive single chain precursor, then cleaved into two chains. The Ser at the new N-terminus at the cleavage site is converted to a pyruvoyl group essential for activity. This type of histidine decarboxylase appears is known so far only in some Gram-positive bacteria, where it may play a role in amino acid catabolism. There is also a pyridoxal phosphate type histidine decarboxylase, as found in human, where histamine is a biologically active amine. [Energy metabolism, Amino acids and amines]
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