Diaminohydroxyphosphoribosylaminopyrimidine deaminase () is an enzyme characterised from Escherichia coli that catalyzes the hydrolysis of 2,5-diamino-6-hydroxy-4-(5-phosphoribosylamino)pyrimidine to 5-amino-6-(5-phospho-β-D-ribosylamino)uracil and ammonia:
The reaction is part of the biosynthesis of riboflavin in Streptomyces davawensis.
This enzyme is a hydrolase, one acting on carbon-nitrogen bonds other than peptide bonds (specifically in cyclic amidines). The systematic name of this enzyme class is 2,5-diamino-6-hydroxy-4-(5-phosphoribosylamino)pyrimidine 2-aminohydrolase.
Structural studies As of late 2007, 6 structures have been solved for this class of enzymes, with PDB accession codes , , , , , and .
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