Dihydropyrimidine amidohydrolases and dihydroorotases share the same origin and several enzymatic properties.
Nucleic Acids Res
; 31(6): 1683-92, 2003 Mar 15.
Article
en En
| MEDLINE
| ID: mdl-12626710
ABSTRACT
Slime mold, plant and insect dihydropyrimidine amidohydrolases (DHPases, EC 3.5.2.2), which catalyze the second step of pyrimidine and several anti-cancer drug degradations, were cloned and shown to functionally replace a defective DHPase enzyme in the yeast Saccharomyces kluyveri. The yeast and slime mold DHPases were over-expressed, shown to contain two zinc ions, characterized for their properties and compared to those of the calf liver enzyme. In general, the kinetic parameters varied widely among the enzymes, the mammalian DHPase having the highest catalytic efficiency. The ring opening was catalyzed most efficiently at pH 8.0 and competitively inhibited by the reaction product, N-carbamyl-beta-alanine. At lower pH values DHPases catalyzed the reverse reaction, the closing of the ring. Apparently, eukaryote DHPases are enzymatically as well as phylogenetically related to the de novo biosynthetic dihydroorotase (DHOase) enzymes. Modeling studies showed that the position of the catalytically critical amino acid residues of bacterial DHOases and eukaryote DHPases overlap. Therefore, only a few modifications might have been necessary during evolution to convert the unspecialized enzyme into anabolic and catabolic ones.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Evolución Molecular
/
Dihidroorotasa
/
Amidohidrolasas
Límite:
Animals
Idioma:
En
Revista:
Nucleic Acids Res
Año:
2003
Tipo del documento:
Article
País de afiliación:
Dinamarca