TITLE

Main Physicochemical Features of Monofunctional Flavokinase from Bacillus subtilis

AUTHOR(S)
Solovieva, I. M.; Tarasov, K. V.; Perumov, D. A.
PUB. DATE
February 2003
SOURCE
Biochemistry (00062979);Feb2003, Vol. 68 Issue 2, p177
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
The main properties of a monofunctional riboflavin kinase from B. subtilis have been studied for the first time; the enzyme is responsible for a key reaction in flavin biosynthesis—the ATP-dependent phosphorylation of riboflavin with production of flavin mononucleotide. The active form of the enzyme is a monomer with molecular weight of about 26 kD with a strict specificity for reduced riboflavin. To display its maximum activity, the enzyme needs ATP and Mg2+. During the phosphorylation of riboflavin, Mg2+ could be partially replaced by ions of other bivalent metals, the efficiencies of which decreased in the series Mg2+ > Mn2+ > Zn2+, whereas Co2+ and Ca2+ had inhibiting effects. The flavokinase activity was maximal at pH 8.5 and 52°C. ATP could be partially replaced by other triphosphates, their donor activity decreasing in the series: ATP > dATP > CTP > UTP. The Michaelis constants for riboflavin and ATP were 0.15 and 112 μM, respectively. As compared to riboflavin, a tenfold excess of its analog 7,8-dimethyl-10-(O-methylacetoxime)-isoalloxazine decreased the enzyme activity by 30%. Other analogs of riboflavin failed to markedly affect the enzyme activity.
ACCESSION #
15100656

 

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