A kinetic study into the hydrolysis of the ochratoxins and analogues by carboxypeptidase A

The hydrolyses of the ochratoxins and analogues by carboxypeptidase A were assessed. This was done by measuring the amount of phenylalanine formed wit h liquid chromatography coupled to tandem electrospray mass spectrometry. T he kinetic data of ochratoxin A, ochratoxin B, and the synthetic bromo-ochr atoxin B were compared to the values of a number of synthesized structure a nalogues, namely, ochratoxin A methyl ester, ochratoxin B methyl ester, N-( 2-hydroxybenzoyl)phenylalanine, N-(5-chloro-2-hydroxybenzoyl)phenylalanine, N-(5-bromo-2-hydroxybenzoyl)phenylalanine, and N-(5-fluoro-2-hydroxybenzoy l)phenylalanine, and N-(5-fluoro-2-hydroxybenzoyl)phenylalanine, The haloge n-containing analogues had lower turnovers than their des-halo analogues. T here are no substantial differences in the kinetic data between the differe nt halogen-containing analogues.