Biotin And Derivatives

Biotin1 is a vitamin that was first recognized as an agent for preventing dermatitis and paralysis in rats fed large quantities of uncooked egg white (which contains abundant quantities of the protein avidin). The vitamin is covalently attached to an e-amino group of an active site lysyl residue in biotin-dependent enzymes. Carboxy-phosphate is thought to be formed prior to carboxyl group transfer to biotin. The N-1' position of biotin then acts as a carboxyl group carrier involved in carboxyla-tion reactions.

Biotin N-l'-Carboxybiotin

Beyond its fundamental role in metabolism, the high affinity of biotin binding to avidin (Kd 10-15 M) and streptavidin has made biotin labeling especially valuable in cell biology1. A protein of interest may be covalently labeled with suitably derivatized, commercially available biotin. For example, one can use N-hydroxysuccinimide or p-nitrophenyl derivatives of biotin to react with amino groups on the target protein.2 The protein's location within cells can be detected by using streptavidin along with a fluorescently labeled anti-streptavidin antibody.

1For a comprehensive discussion of the reactions and properties of vitamins and cofactors, readers are urged to consult Biochemistry: The Chemical Reactions of Living Cells (2nd ed.) by D. E. Metzler (2000) Academic Press, Orlando. This text and reference book contains a valuable compilation of literature citations. 2The Pierce Chemical Company (Rockford, Illinois) freely distributes Avidin-Biotin Chemistry: A Handbook to interested researchers.

Selected entries from Methods in Enzymology [vol, page(s)]: Isotopic dilution assay for biotin use of [14C]biotin, 62, 279; use of [3H]biotin, 62, 284; rapid fluorometric assay for avidin and biotin, 62, 287; microassay of avidin, 62, 290; radioimmunoassay for chicken avidin, 62, 292; the synthesis and use of spin-labeled analogs of biotin in the study of avidin, 62, 295; the avidin-biotin complex in affinity cytochemistry, 62, 308; egg yolk biotin-bind-ing protein: assay and purification, 62, 316; antibodies that bind biotin and inhibit biotin-containing enzymes, 62, 319; microbiological biosynthesis of biotin, 62, 326; preparation of pimeloyl-co-enzyme A, 62, 339; 7,8-diaminopelargonic acid aminotransferase, 62, 342; dethiobiotin synthetase, 62, 348; synthesis and use of specifically tritiated dethiobiotin in the study of biotin biosynthesis by Aspergillus niger, 62, 353; the biotin transport system in yeast, 62, 371; enzymic reduction of D-biotin D-sulfoxide to D-biotin, 62, 379; isolation and characterization of D-allobisnorbiotin, 62, 385; analysis of microbial biotin proteins, 62, 390; identification of biocytin, 62, 398.

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