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Reversible modification of thiol-containing polypeptides with poly (ethylene glycol) through formation of mixed disulfide bonds. The case of papaya proteinase III.

par Musu, Tony;Azarkan, Mohamed ;Brygier, Jeanne;Paul, Claudine ;Vincentelli, Jean ;Volant-Baeyens, Danielle ;Guermant, Claude ;Nijs, Michelle ;Looze, Yvan
Référence Applied biochemistry and biotechnology, 56, 3, page (243-263)
Publication Publié, 1996-03

Article révisé par les pairs

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Résumé :

Papaya proteinase III (PPIII) was purified, as the S-methylthio derivative from the latex of Carica papaya L., by ion-exchange chromatography. Separation of reactivable PPIII from the irreversibly oxidized molecular species of this enzyme was readily achieved after a selective conversion of the reactivated proteinase into the S-monomethoxypoly(ethylene glycol)thio derivative (S-mPEG thio PPIII). From this derivative, a PPIII preparation titrating 1 mol of thiol/mol of enzyme was regenerated. From the physicochemical properties of S-mPEG thio PPIII that were investigated, it is concluded that interactions between the mPEG and the PPIII chains occur only to a limited extent. In addition to its usefulness for purifying thiol-containing enzymes, the mPEG modification resulting from mixed disulfide bond formation may find other practical applications.