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Curr Opin Chem Biol. 1999 Oct;3(5):623-9.

The enzymology of sulfur activation during thiamin and biotin biosynthesis.

Author information

1
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA. tpb2@cornell.edu.

Abstract

The thiamin and biotin biosynthetic pathways utilize elaborate strategies for the transfer of sulfur from cysteine to cofactor precursors. For thiamin, the sulfur atom of cysteine is transferred to a 66-amino-acid peptide (ThiS) to form a carboxy-terminal thiocarboxylate group. This sulfur transfer requires three enzymes and proceeds via a ThiS-acyladenylate intermediate. The biotin synthase Fe-S cluster functions as the immediate sulfur donor for biotin formation. C-S bond formation proceeds via radical intermediates that are generated by hydrogen atom transfer from dethiobiotin to the adenosyl radical. This radical is formed by the reductive cleavage of S-adenosylmethionine by the reduced Fe-S cluster of biotin synthase.

PMID:
10508664
[Indexed for MEDLINE]
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