Ogawa J, Shimizu S
Department of Agricultural Chemistry, Kyoto University, Japan.
Eur J Biochem. 1994 Jul 15;223(2):625-30. doi: 10.1111/j.1432-1033.1994.tb19034.x.
beta-Ureidopropionase of aerobic bacterial origin was purified to homogeneity from Pseudomonas putida IFO 12996. The enzyme shows a broad substrate specificity. In addition to beta-ureidopropionate (Km 3.74 mM, Vmax 4.12 U/mg), gamma-ureido-n-butyrate (Km 11.6 mM, Vmax 19.4 U/mg), and several N-carbamoyl-alpha-amino acids, such as N-carbamoylglycine (Km 0.68 mM, Vmax 9.14 x 10(-2) U/mg), N-carbamoyl-L-alanine (Km 1.56 mM, Vmax 1.00 U/mg), N-carbamoyl-L-serine (Km 75.1 mM, Vmax 3.78 U/mg), and N-carbamoyl-DL-alpha-amino-n-butyrate (Km 2.81 mM, Vmax 1.08 U/mg), are also hydrolyzed. The hydrolysis of N-carbamoyl-alpha-amino acids is strictly L enantiomer specific. N-Formyl-L-alanine and N-acetyl-L-alanine are also hydrolyzed by the enzyme, but the rate of hydrolysis is lower than the rate for N-carbamoyl-L-alanine. The enzyme requires a divalent metal ion, such as Co2+, Ni2+ or Mn2+, for activity, and is significantly affected by sulfhydryl reagents. The enzyme consists of two polypeptide chains with identical relative molecular mass M(r) 45000. The broad substrate specificity and metal ion dependence of the enzyme show that the beta-ureidopropionase of this aerobic bacterium is quite different from the beta-ureidopropionases of mammals and anaerobic bacteria.
从恶臭假单胞菌IFO 12996中纯化出了具有同源性的需氧细菌来源的β-脲基丙酸酶。该酶具有广泛的底物特异性。除了β-脲基丙酸（Km为3.74 mM，Vmax为4.12 U/mg）、γ-脲基正丁酸（Km为11.6 mM，Vmax为19.4 U/mg）以及几种N-氨基甲酰-α-氨基酸，如N-氨基甲酰甘氨酸（Km为0.68 mM，Vmax为9.14×10⁻² U/mg）、N-氨基甲酰-L-丙氨酸（Km为1.56 mM，Vmax为1.00 U/mg）、N-氨基甲酰-L-丝氨酸（Km为75.1 mM，Vmax为3.78 U/mg）和N-氨基甲酰-DL-α-氨基正丁酸（Km为2.81 mM，Vmax为1.08 U/mg）也能被水解。N-氨基甲酰-α-氨基酸的水解严格具有L对映体特异性。N-甲酰-L-丙氨酸和N-乙酰-L-丙氨酸也能被该酶水解，但水解速率低于N-氨基甲酰-L-丙氨酸的水解速率。该酶的活性需要二价金属离子，如Co²⁺、Ni²⁺或Mn²⁺，并且受到巯基试剂的显著影响。该酶由两条相对分子质量相同（Mr为45000）的多肽链组成。该酶广泛的底物特异性和对金属离子的依赖性表明，这种需氧细菌的β-脲基丙酸酶与哺乳动物和厌氧细菌的β-脲基丙酸酶有很大不同。
