title: The fidelity of gramicidin S synthetase.
abstract: The amino acid analog L-cyclohexylalanine, which may be considered an analog of the hydrophobic amino acids leucine and valine, was found to thioester-bind to the heavy enzyme of gramicidin S synthetase. The results indicate that it preferably binds to the thiol site of leucine, although binding to the valine site also occurs. In the synthesis of the cyclic decapeptide by gramicidin S synthetase, the results suggest that L-cyclohexylalanine can replace L-leucine and L-valine. We have also found that in the synthesis of the cyclic decapeptidase L-leucine can replace L-valine and vice versa. The results further indicate that the previously reported thioester binding of D and L-phenylalanine to the heavy enzyme takes place at the thiol site of leucine.
mesh_terms: D000591:Amino Acid Isomerases / Q000378:metabolism*; D001407:Bacillus / Q000201:enzymology*; D007700:Kinetics; D007930:Leucine; D009097:Multienzyme Complexes / Q000378:metabolism*; D009842:Oligopeptides / Q000138:chemical synthesis; D010453:Peptide Synthases / Q000378:metabolism*; D010456:Peptides, Cyclic / Q000138:chemical synthesis; D010649:Phenylalanine / Q000031:analogs & derivatives; D011485:Protein Binding; D013379:Substrate Specificity; D014633:Valine
chemical_list: D009097:Multienzyme Complexes; D009842:Oligopeptides; D010456:Peptides, Cyclic; C028544:cyclohexylalanine; D010649:Phenylalanine; D000591:Amino Acid Isomerases; D010453:Peptide Synthases; C020831:gramicidin-S-synthetase 2; D007930:Leucine; D014633:Valine