Biotin synthase, a new member of the family of enzymes which uses S-adenosylmethionine as a source of deoxyadenosyl radical.
The fact that biotin synthase, from Escherichia coli and Bacillus sphaericus, requires S-adenosylmethionine and a reducing system led us to postulate that this synthase could belong to the family of enzymes which use S-adenosylmethionine as a source of deoxyadenosyl radical, namely pyruvate formate-lyase, lysine 2,3-aminomutase, and anaerobic ribonucleotide reductase. We describe here experiments with S-[2,8-(3)H] adenosylmethionine and S-adenosyl-[methyl-3H]methionine which allowed the identification and quantification of the expected cleavage products, deoxyadenosine, and methionine. They are formed in equimolar amounts, in a ratio close to 3 with respect to the biotin produced. We postulate a mechanism involving the homolytic cleavage of two C-H bonds which should consume two equivalents of S-adenosylmethionine. The observed excess of S-adenosylmethionine consumption is attributed to abortive processes.
Guianvarc'h
D
D
Laboratoire de Chimie Organique Biologique, Université Paris VI, France.
Florentin
D
D
Tse Sum Bui
B
B
Nunzi
F
F
Marquet
A
A
D001407:Bacillus / Q000201:enzymology*; D001710:Biotin / Q000096:biosynthesis*; D004926:Escherichia coli / Q000201:enzymology*; D005609:Free Radicals; D012436:S-Adenosylmethionine / Q000737:chemistry / Q000378:metabolism*; D013466:Sulfurtransferases / Q000378:metabolism*
D005609:Free Radicals; D001710:Biotin; D012436:S-Adenosylmethionine; D013466:Sulfurtransferases; C057985:biotin synthetase