[Amidation of proteins and peptides with carboxypeptidase Y].

The native and modified carboxypeptidase Y-catalyzed reaction of acyl transfer of acylamino acid and peptide residues from the corresponding esters to ammonia was studied. Use of the modified carboxypeptidase Y increased the yield of the resulting product. Calcitonin-Leu was transformed into human calcitonin.

[C-terminal amidation of acylamino acids and peptides using a transpeptidation method catalyzed by carboxypeptidase Y].

The carboxypeptidase Y-catalyzed reaction of acyl transfer of acylamino acid and peptide residues from the corresponding esters to ammonia and to amides of amino acids has been studied, and conditions for obtaining amides of amino acids and peptides with the yields up to 90% found.

[Mechanism of oxygen exchange in the amide group of substrates during their hydrolysis catalyzed by leucine aminopeptidase and pepsin].

Oxygen exchange in the amide group of leucine amide catalyzed by leucine aminopeptidase, and in leucyltyrosine amide catalyzed by porcine pepsin, was found to proceed mainly by the transfer of the leucyl residue onto the ammonia or tyrosine amide which are formed during the hydrolysis. Thus oxygen exchange in the non-hydrolyzed substrate can not be a proof of the tetrahedral intermediate formation in the course of the catalysis by proteolytic enzymes.