COMPLEXATION OF PEPSIN POLY(ETHYLENE GLYCOL)

Complexation of porcine pepsin (or pepsin A) (EC.3.4.23.1) with poly(ethylene glycol) (PEG) in an aqueous solution was studied as a function of pH and PEG concentration. The addition of PEG increased the reduced viscosity of the enzyme solution at pH 3 but not at pH 4.5. An increase in pH was observed by mixing both PEG and enzyme solutions which were previously adjusted to pH 3. Under conditions of pH 2.5-3 and 50-degrees-C, PEG contributed to an increase in the hydrolyzing activity of pepsin toward N-acetyl-L-phenylalanyl-3,5-diiodo-L-tyrosine. These results indicate that pepsin forms a water-soluble complex with PEG mainly through hydrogen bonds between the carboxyl groups in the enzyme and the ether groups in PEG.