title: Studies on peptide amidase-catalysed C-terminal peptide amidation in organic media with respect to its substrate specificity.
abstract: Peptide amidase-catalysed amidations of the C- terminal carboxylic group of peptides were studied using model substrates of a large series of N(alpha)-protected di-, tri-, tetra- and penta-peptides in the presence of NH4HCO3 as the ammonium source. The maximal yields of amide syntheses were achieved in a medium consisting of acetonitrile with 20-25 vol% of dimethylformamide and 3 vol% of water. Under these conditions, the substrate specificity of the enzyme was more restricted in the synthetic reaction than was found for the amide hydrolysis. Elongation of the peptide chain had a negative effect on enzymic amidation. Thus the direct amidation of N(alpha)-t-butoxycarbonyl-protected Leu-enkephalin resulted in a low yield of protected enkephalin amide.
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo 2, Prague 6, 166 10, Czech Republic.
authors.forename: V
authors.initials: V
authors.lastname: Cerovský
authors.forename: M R
authors.initials: MR
authors.lastname: Kula
mesh_terms: D000581:Amidohydrolases; D001671:Biochemistry / Q000379:methods; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D012997:Solvents; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D010455:Peptides; D012997:Solvents; D000581:Amidohydrolases