Catalyses by polymer complexes. VII. Enhanced esterolytic reactivity of polymer‐coenzyme A, glutathione complexes

The association of coenzyme A(CoASH) and glutathione (GSH) with the water‐soluble polymers and their esterolytic reactivities were evaluated through the reaction with p‐nitrophenyl acetate in the presence of cationic polymer micelles: partially laurylated poly(2‐ethyl‐1‐vinylimidazole) and poly(4‐vinylpyridine). The polymer micelles with high lauryl‐group content (more than 12 mol%) markedly accelerated the reaction at very low concentrations of the polymer. Other polymers with no or small lauryl‐group content only slightly enhanced the association and the reaction rate. From the rate‐polymer concentration profiles, the association constants (K) and the rate constants for thiol coenzymes bound to the polymer (k′_a,bound) were determined: for polymers with more than 12 mol % lauryl‐group content, K_CoASH = 1110–2270 M⁻¹, K_GSH = 170–503M⁻¹, k′_a,bound at pH 8.65 = 142–341M⁻¹ sec⁻¹. k′_a,bound were 20–340 times larger than that observed in the absence of the polymer. The logarithm of k′_a,bound was found to be correlated well with the polymer hydrophobicity, indicating that the hydrophobic environment of the polymer activated the bound thiol anions. On the other hand, the polymer hydrophobicity did not correlate with the association constant.