169698-16-2Relevant academic research and scientific papers
Carboxypeptidase A-Catalyzed Hydrolysis of α-(Acylamino)cinnamoyl Derivatives of L-β-Phenyllactate and L-Phenylalaninate: Evidence for Acyl-Enzyme Intermediates
Suh, Junghun,Cho, Wonhwa,Chung, Shin
, p. 4530 - 4535 (1985)
The (CPA) carboxypeptidase A-catalyzed hydrolysis of α-(acetylamino)- (1), α-(benzoylamino)- (2), or α-cinnamoyl ester (3) of L-β-phenyllactate manifested small values of both kcat and Kmapp.On the other hand, the corresponding amides of L-Phe showed enhanced kcat and unaffected Kmapp values.At -2 deg C, accumulation of an intermediate was observed spectrophotometrically immediately after mixing of 6x10-5 M CPA with 4x10-5 M 3.This is the most stable (in terms of half-life and Kmapp) intermediate ever reported for the CPA-catalyzed reactions.For 2 and 3, kcat was independent of pH over pH 5.5-9.5.Although attempts to trap the intermediate with external or intramolecular trapping reagents were unseccesful, the very small Kmapp and the pH independence of kcat for 2 and 3 provide evidence that shows that the accumulating intermediate is the anhydride acyl-CPA intermediate.The temperature dependence and the D2O effect were measured for the kcat values of 2 and 3.The different effects of the α-(acylamino)cynnamoyl groups on the kinetic parameters for esters and for peptides were explained in terms of a single mechanism with the intermediacy of an acyl-enzyme.
