Über natürliche Aktivatoren und Hemmungskörper proteolytischer Enzyme.

A Review of the Literature on the Potential Therapeutic Significance of Papain

“…The preparation must be dialyzed to remove the natural activators, which may lead to erroneous interpretation of the action of the supposedly purified enzyme. 131 The natural activator of papain was first named as phytokinase, a thermolabile substance destroyed by b0i1ing.l~~ A similar substance, zookinase, which activates both cathepsin and papain, was also found in animal 185 These activators were shown to be reduced glutathione.Is6 This was also supported by later but its presence in the pulp of the fruit as previously claimed176 was denied.67 Other workers have also recognized the presence of a natural activator in papain, but its identity with glutathione was doubted.42. 44.…”

Proteolytic Enzymes

“…The physiological significance of these findings was emphasized by the demonstration (Grassman, Dyckerhoff, and von Schoenebeck, 1930) that many intracellular proteases, both plant and animal, are accompanied by sulfhydryl compounds which serve as natural activators, presumably by virtue of their reducing action. A theory for the mechanism of the activation of papain by reducing agents, and of the reversible inactivation of papain by careful use of oxidizing agents such as iodine or hydrogen peroxide (Bersin, 1933(Bersin, , 1934 was developed by Bersin (1935) and Hellerman (1937), who suggested that the disulfide form of the enzyme (En--S--S--En) is inactive, and that reduction of disulfide groups to active sulfhydryl groups activates the enzyme: reduction En--S---S--En + 2H + -t-2(e) ' oxidation .... 2En -SH This sulfhydryl mechanism has been extended by HeUerman (1937) and has been applied to many other enzymes.…”