Abstract
Imidase is an enzyme, also known as dihydropyrimidinase (EC 3.5.2.2), hydantoinase, dihydropyrimidine hydrase or dihydropyrimidine amidohydrolase, that catalyzes the reversible hydrolysis of 5,6-dihydrouracil to 3-ureidopropionate and many other imides. Substrate specificity, metal content and amino-acid sequence all differ significantly between bacterial and mammalian imide-hydrolyzing enzymes. In this study, a thermophilic imidase was isolated from pig liver and crystallized. Two kinds of imidase crystals were grown by the hanging-drop vapour-diffusion method using polyethylene glycol MME 5000 and 2-propanol as precipitants. One belongs to the triclinic P 1 space group, with unit-cell parameters a = 96.35, b = 96.87, c = 154.87 Å, α = 82.10, β = 72.54, γ = 77.19°, and the other belongs to the orthorhombic C222 1 space group, with unit-cell parameters a = 113.92, b = 157.22, c = 156.21 Å.