Reversible modification of thiol-containing polypeptides with poly(ethylene glycol) through formation of mixed disulfide bonds
- 1 March 1996
- journal article
- Published by Springer Nature in Applied Biochemistry and Biotechnology
- Vol. 56 (3) , 243-263
- https://doi.org/10.1007/bf02786956
Abstract
Papaya proteinase III (PPIII) was purified, as the S-methylthio derivative from the latex ofCarica 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.Keywords
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