title: Enzymatic characterization of 5-methylthioribulose-1-phosphate dehydratase of the methionine salvage pathway in Bacillus subtilis.
abstract: 5-Methylthioribulose-1-phosphate (MTRu-1-P) dehydratase catalyzes the reaction from MTRu-1-P to 2,3-diketo-5-methylthiopentyl-1-phosphate (DK-MTP-1-P) in the methionine salvage pathway in Bacillus subtilis. The properties of this enzyme remain to be determined. We characterized these properties using a recombinant protein. The enzyme, with a molecular mass of 90 kDa, was composed of four subunits. The K(m) and V(max) of the enzyme were 8.9 microM and 42.7 micromole min(-1) mg protein(-1) at 25 degrees C respectively. Maximum activity was observed at pH 7.5 to 8.5 and 40 degrees C. The activation energy of the reaction from MTRu-1-P to DK-MTP-1-P was 63.5 kJ mol(-1). The reaction product DK-MTP-1-P was labile, and decomposed at a rate constant of 0.048 s(-1) to an unknown compound that was not utilized by DK-MTP-1-P enolase, the enzyme catalyzing the next step. The function of this enzyme in the pathway is discussed.
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama, Ikoma, Nara 630-0192, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Ashida
authors.forename: Yohtaro
authors.initials: Y
authors.lastname: Saito
authors.forename: Chojiro
authors.initials: C
authors.lastname: Kojima
authors.forename: Akiho
authors.initials: A
authors.lastname: Yokota
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology* / Q000378:metabolism; D006836:Hydro-Lyases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008715:Methionine / Q000378:metabolism*; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D012274:Ribulosephosphates / Q000378:metabolism*; D013696:Temperature
chemical_list: D012274:Ribulosephosphates; C038238:1-phospho-5-S-methylthioribulose; D008715:Methionine; D006836:Hydro-Lyases; D010751:Phosphopyruvate Hydratase