title: The origin of sulfur in biotin.
abstract: The comparative ability of Escherichia coli K-12 hpb lambda-, a biotin overproducing strain, to incorporate 35S from isotopically labeled L-methionine, L-cystine, and the sulfane sulfur of thiocystine was determined. Comparison of the specific activity of sulfur in biotin produced by the organism with that of the 35S-labeled amino acids demonstrates that the sulfur of cystine is transferred to biotin with an efficiency of at least 75%, that the sulfur of methionine does not contribute to biotin significantly, and that the sulfane sulfur of thiocystine contributes approximately one-third of the sulfur to newly synthesized biotin and is essentially equivalent in utilization to that of the other two sulfur atoms in the molecule.
mesh_terms: D001710:Biotin / Q000096:biosynthesis*; D003553:Cystine / Q000031:analogs & derivatives / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism*; D007700:Kinetics; D008715:Methionine / Q000378:metabolism; D009154:Mutation; D013455:Sulfur / Q000378:metabolism*; D013462:Sulfur Radioisotopes
chemical_list: D013462:Sulfur Radioisotopes; C019572:thiocystine; D003553:Cystine; D001710:Biotin; D013455:Sulfur; D008715:Methionine