Complex of papaya proteinases modified with soluble polymer and its possible medical application

A water-soluble enzymatic preparation was obtained by coimmobilization of papaya proteinase complex together with cysteine on aldehyde dextran. The product formed possesses an extended pH optimum of catalytic activity, and increased stability, including storage stability. The formation of a protective microenvironment from cysteine sulfhydryl groups favors the fixation of catalytically active enzyme conformers upon their immobilization on the polymeric carrier. The stability of native and aldehyde dextran-cysteine-modified papaya proteinase complex towards the action of extreme pH, proteolysis, and temperature was comparatively studied. It was demonstrated that the stabilizing effect of the polymeric carrier is determined by the “strengthening” of the biocatalyst structure and by the prevention of protein association via thioldisulfide exchange reaction. The latter is the results of steric hindrance created by the carrier. At extreme pH values a destruction of the preparations occurs, which increases in the presence of pronase. The partial destruction of the carrier in the modified preparation does not decrease thermostability of the latter. The modification of the preparation increases its stability and diminishes degradation at extreme pH values. The therapeutic efficiency of the modified preparation has been demonstrated at ophthalmologic lesions.