[Conjugates of alpha-chymotrypsin with polyalkylene oxides in hydrated reverse micelles].

Conjugates of alpha-chymotrypsin (ChT) with poly(ethylene glycol) (PEG) and block copolymers of ethylene oxide and propylene oxide (proxanols) have been synthesized. The molecular mass of the polymers was 2 kDa. The conjugates contained 5 to 7 polymeric chains per enzyme molecule. Hydrolysis of N-trans-cinnamoylimidazole catalyzed by conjugates of ChT with poly(alkylene oxides) was studied in 0.05 M Tris-HCl buffer, pH 8.0, and in hydrated reversed micelles of aerosol OT (AOT) in octane at 25 degrees C. The deacylation constant, k3, for the conjugates in the buffer solution was found to be 1.5-1.8-fold higher than the corresponding value for native ChT. The value of the [H2O]/[AOT] ratio corresponding to the maximum on the k3 versus [H2O]/[AOT] curves for the conjugates (around 16) allows the dimensions of their molecules to be characterized. The radius of the conjugate molecules was found to be approximately equal to 2.8 nm. The k3 value for the conjugate of ChT with PEG, as in the case of native ChT, remains constant when the concentration of AOT is varied. However, the deacylation constant for ChT conjugates with proxanols decreases with a rise in AOT concentration. This fact indicates that ChT conjugates with proxanols are able to interact with the micellar matrix, i.e., they possess membranotropic properties.