α-Chymotrypsin Catalyzed Hydrolysis of N-Benzoyl-L-Tyrosine Ethyl Ester Anchored in β-Cyclodextrin

Abstract

N-Benzoyl-L-tyrosine ethyl ester, a substrate for α-chymotrypsin (EC. 3.4.21.1) was solubilised by β-cyclodextrin at a molar ratio of 1.0:2.0 but not by α-cyclodextrin. The completely water soluble BTEE-β-cyclodextrin complex served as an excellent substrate for the enzyme α-chymotrypsin. The rate of hydrolysis of such a cyclodextrin anchored BTEE was identical to that of the substrate in Triton X-100 micelles, but was higher than the methanol solubilised substrate. The pH-activity profile was similar for all the three substrate preparations. The specificity constant (k_cat/K_m) was higher in the case of BTEE-β-cyclodextrin compared to the methanol and Triton X-100 solubilised substrates. However, the enthalpy of activation was found to be increased in the case of Triton X-100 and β-cyclodextrin anchored substrates.

Key Words:

• β-Cyclodextrin
• α-Chymotrypsin
• Anchored catalysis