Structure of the carboxypeptidase t from <i>Thermoactinomyces vulgaris</i> complex with <i>L</i> - phenyl lactate

The crystal structure of the metallocarboxypeptidase T from Thermoactinomyces vulgaris complex with L-phenylactate was obtained with a resolution of 1.73 Å. Unlike pancreatic carboxypeptidase A, which binds one L-phenylactate molecule, in complex with CPT, the ligand occupies both S1 and S1ʹ sites of the active center simultaneously. In this case, conformational changes occur that differ from the changes caused by the alternate occupation of the S1 and S1ʹ sites by BOC-leucine and benzylsuccinic acid. These changes concern the residues E277, E59, L254, G192, S127 and Y218 and reach a span of 0.77 Å. A conclusion is made about the possible role of these residues in the recognition and catalysis of substrates by carboxypeptidase T.