Peptidyl transfers in gramicidin S bisoynthesis from enzyme-bound thioester intermediates.
The biosynthesis of the peptide antibiotic gramicidin S involves successive peptidyl transfer reactions between intermediates bound in thioester linkages to two active enzyme fractions, I and II. Fraction II activates and recemizes phenylalanine, and then initiates peptidyl transfer by catalyzing a reaction between the carboxyl group of D-phenylalanine, bound to an enzymic sulfhydryl group, and the free imino group of L-proline, one of four L-amino acids all linked by their carboxyl functions to separate sulfhydryl groups on fraction I. Successive reactions of this type in the active centers of the multienzyme complex of fraction I lead to the formation of thioester-bonded nascent peptide chains and, ultimately, of the antibiotic product.
D000595:Amino Acid Sequence; D004952:Esters; D008970:Molecular Weight; D010455:Peptides / Q000378:metabolism*; D011485:Protein Binding; D013438:Sulfhydryl Compounds; D013455:Sulfur; D014166:Transferases / Q000378:metabolism; D014449:Tyrothricin / Q000096:biosynthesis*
D004952:Esters; D010455:Peptides; D013438:Sulfhydryl Compounds; D014449:Tyrothricin; D013455:Sulfur; D014166:Transferases