Expression and properties of human liver beta-ureidopropionase.
A cDNA encoding beta-ureidopropionase (BUP) was isolated from a human liver cDNA library, expressed in E. coli, and purified from the culture extract. The 2,006 bp cDNA contained a 1,152 bp open reading frame encoding a protein of 384 amino acids with a molecular weight of 43,165 Da. The subunit molecular weight of the enzyme expressed was about 43,000 Da. The enzyme was inhibited by 1 mM propionate, but not by 10 mM beta-alanine. Chemical analysis of the purified human BUP showed 0.54 zinc atoms per subunit, and the sequence of BUP cDNA contained one putative zinc-binding site motif. The purified enzyme had a pI of 5.65, and exhibited positive cooperativity with N-carbamoyl-beta-alanine as the substrate with a Hill coefficient 2.0. These properties of human BUP, except the inhibition by beta-alanine, were similar to the rat liver purified enzyme. Beta-alanine inhibits rats BUP activity. The complex regulatory function and the negative cooperative mechanism of BUP by beta-alanine have been observed in rats. This kind of mechanism may not exist in humans, because beta-alanine did not inhibit human BUP.
Sakamoto
T
T
Faculty of Nutrition and High Technology Research Center, Kobe Gakuin University, Japan.
Sakata
S F
SF
Matsuda
K
K
Horikawa
Y
Y
Tamaki
N
N
D000581:Amidohydrolases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000302:isolation & purification; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D008099:Liver / Q000201:enzymology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016366:Open Reading Frames; D051381:Rats; D016415:Sequence Alignment; D014018:Tissue Distribution
D018076:DNA, Complementary; D000581:Amidohydrolases; C021590:beta-ureidopropionase