Purification and Properties of Purine Nucleoside Phosphorylase from Brevibacterium acetylicum ATCC 954(Microbiology & Fermentation Industry)

概要

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Purine nucleoside phosphorylase of Brevibacterium acetylicum ATCC 954, which catalyzes the production of ribavirin (1-β-D-ribofuranosyl-1,2,4-triazole-3-carboxamide), a potent antiviral agent, from purine nucleoside and 1,2,4-triazole-3-carboxamide in a high yield, was purified 49-fold. This enzyme had a molecular weight of 31,000 and was a monomer. The isoelectric point of the enzyme was 4.7. The optimal temperature and pH of inosine phosphorolyzing reaction catalyzed by the enzyme was around 8.5 and 70℃, respectively. The Michaelis constants for inosine, guanosine, and ribavirin were 1.43 mM, 2.44 mM and 2.08 mM, respectively, at 40℃. This enzyme appeared to be a SH enzyme because it was inactivated by SH reagents, p-chloromercuribenzoate and N-ethylmaleimide, and HgCl_2. In addition, this enzyme was completely inactivated by AgNO_3 and was slightly inhibited by CuSO_4. It showed nucleoside-phosphorolyzing activity toward inosine, 2'-deoxyinosine, 2',3'-dideoxyinosine, guanosine, 2'-deoxyguanosine, and xanthosine. However, adenosine and its derivatives could not be phosphorolyzed. This enzyme could not also phosphorolyze various 5'-mononucleotides. According to the amino terminal sequence analysis, the twenty residues from the amino terminal end of this enzyme were identified as follows: MTVNWNETRS-FLECKMQAKPE.
社団法人日本農芸化学会の論文
1991-02-23