Influence of solvent viscosity on the rate of hydrolysis of dipeptides by carboxypeptidase Y

The influence of solvent viscosity on the rate of enzymatic hydrolysis of a series of dipeptides (Z‐Phe‐Gly, Z‐Phe‐Sar, Z‐Phe‐Ala, Z‐Phe‐NMeAla, Z‐Phe‐Aib and Z‐Phe‐Pro) by carboxypeptidase Y was investigated. The effect of solvent viscosity on the enzymatic hydrolysis revealed that whereas all k cat values decreased with viscosity, those of the N ‐alkyl peptides decreased more than those of the N ‐H peptides. The kinetic behaviour implies the involvement of conformational changes of the enzyme in terms of the ‘induced‐fit’ process.