α-Chymotryptic Hydrolysis of Derivatives of the Specific Substrates with Substituents in the Nucleus

抄録

Steady state kinetic studes of α-chymotrypsin [EC 3. 4. 21.l]-catalyzed hydrolysis of nucleus-substituted derivatives of the specific substrates were made at pH 6.5 and 7.8. Ac-Trp (NCps)-OMe was hydrolyzed more readily than Ac-Trp-OMe owing to its smaller Km value. The k_cat values of Ac-Trp (CHO)-OMe and Ac-Tyr (3-NO₂)-OMe were higher than those of the corresponding unmodified substrates, suggesting that derivatives with a substituent as large as a formyl or nitro group at the s-position are stereochemically favorable to the catalytic process. Derivatives of Ac-Phe-OMe with a chain of four atoms at the 3 or 4-position of the phenyl nucleus and 2, 3-dihydropyrrolo[2, 3-b]indoles derived from Ac-Trp-OMe were not hydrolyzed at all.