L-Hydantoinases (L-HYDs) and Allantoinase (ALN); L-Hydantoinases are a member of the dihydropyrimidinase family, which catalyzes the reversible hydrolytic ring opening of dihydropyrimidines and hydantoins (five-membered cyclic diamides used in biotechnology). But L-HYDs differ by having an L-enantio specificity and by lacking activity on possible natural substrates such as dihydropyrimidines. Allantoinase catalyzes the hydrolytic cleavage of the five-member ring of allantoin (5-ureidohydantoin) to form allantoic acid.
Jiyao W et al.(2023). "The conserved domain database in 2023.",