Conjugates of alpha-chymotrypsin with poly(alkylene oxides) in hydrated reversed micelles

Conjugates of alpha-chymotrypsin (ChT)(4) with poly(ethylene glycol) (PEG) and block copolymers of ethylene oxide and propylene oxide (proxanols) have been synthesized. The molecular mass of polymers used was 2 kD. Conjugates contained 5 to 7 polymeric chains per enzyme molecule. Hydrolysis of N-trans-cinnamoylimidazole catalyzed by the ChT conjugates with poly(alkylene oxides) was studied in 0.05 M Tris-HCl buffer, pH 8.0, and in the system of the hydrated reversed micelles of aerosol OT (AOT) in octane at 25 degrees C. The deacylation constant, k(3), for the conjugates in the buffer solution was found to be 1.5-1.8-fold higher than the k(3) value for native ChT. The value of the [H2O]/[AOT] ratio corresponding to the maximum on the kg versus [H2O]/[AOT] curves for the conjugates (similar to 16) allows the dimensions of their molecules to be characterized. The radius of the conjugate molecules was found to be similar to 2.8 nm, The value of k(3) for the ChT conjugate with PEG, as in the case of native ChT, remains constant when the concentration of AOT is varied. However, the deacylation constant for the ChT conjugates with proxanols decreases with an increase in AOT concentration. This fact indicates that the ChT conjugates with proxanols are able to interact with the micellar matrix, i.e., they are membranotropic compounds.