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M20 Peptidase beta-alanine synthase, an amidohydrolase Peptidase M20 family, beta-alanine synthase (bAS; N-carbamoyl-beta-alanine amidohydrolase and beta-ureidopropionase; EC 3.5.1.6) subfamily. bAS is an amidohydrolase and is the final enzyme in the pyrimidine catabolic pathway, which is involved in the regulation of the cellular pyrimidine pool. bAS catalyzes the irreversible hydrolysis of the N-carbamylated beta-amino acids to beta-alanine or aminoisobutyrate with the release of carbon dioxide and ammonia. Also included in this subfamily is allantoate amidohydrolase (allantoate deiminase), which catalyzes the conversion of allantoate to (S)-ureidoglycolate, one of the crucial alternate steps in purine metabolism. It is possible that these two enzymes arose from the same ancestral peptidase that evolved into two structurally related enzymes with distinct catalytic properties and biochemical roles within the cell. Downstream enzyme (S)-ureidoglycolate amidohydrolase (UAH) is homologous in structure and sequence with AAH and catalyzes the conversion of (S)-ureidoglycolate into glyoxylate, releasing two molecules of ammonia as by-products. Yeast requires beta-alanine as a precursor of pantothenate and coenzyme A biosynthesis, but generates it mostly via degradation of spermine. Disorders in pyrimidine degradation and beta-alanine metabolism caused by beta-ureidopropionase deficiency (UPB1 gene) in humans are normally associated with neurological disorders. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",