Disulfide-sulfhydryl interchange

In the initial research of Anfinsen and co-workers (1961), on ribonuclease as in most studies of the same period, disulfide bonds reformation were produced by air reoxidation. In air reoxidation regeneration, correction of incorrect disulfide bonds occurs through disulfide-sulfhydryl interchange, either by an intramolecular process such as... 

Since part of the insolubilization of heated soy milk protein during drying occurs through the sulfhydryl/disulfide bond interchange reaction, experiments were carried out so as to distinguish... 

Mucolytics. — Studies with acetylcysteine continue to show this compound, alone and in combination with isoproterenol, demonstrates a significant and real mucolytic action greater than that produced by water, saline, detergents or enzymes. The principal mucolytic action of a sulfhydryl interchange with disulfide bonds in the mucoproteins appears to be... 

Figure 1.73 The disulfide group of a cystamine-modified protein may undergo disulfide interchange reactions with another sulfhydryl-containing protein to yield a disulfide-linked conjugate.

Figure 21.10 Cystamine may be used to make immunotoxin conjugates by a disulfide interchange reaction. Modification of antibody molecules using an EDC-mediated reaction creates a sulfhydryl-reactive derivative. A-chain toxin subunits containing a free thiol can be coupled to the cystamine-modified antibody to form disulfide crosslinks.

This enzyme [EC 5.3.4.1], also known as S—S rearran-gase, catalyzes the rearrangement of intrachain or interchain disulfide bonds within proteins to form then-native structures. The enzyme requires reducing agents or the partly reduced enzyme. The reaction operates by sulfhydryl-disulfide interchange. 

SULFATE ADENYLYLTRANSFERASE SULFATE ADENYLYLTRANSFERASE (ADR) Sulfhydryl-disulfide interchange,... 

In an earlier experiment, Jori et al. (14) reported that methionyl residues are important in maintaining the tertiary structure of lysozyme. The introduction of a polar center into the aliphatic side chain of methionine, as a consequence of the conversion of the thioether function to the sulfoxide, may bring about a structural change of the lysozyme molecule which, in turn, reduces the catalytic efficiency. When ozonized lysozyme was treated with 2-mercaptoethanol in an aqueous solution according to the procedure of Jori e al. (14), the enzyme did not show any increase in its activity. This may be explained in two ways. In one, such reactions are complicated by many side reactions, e.g. sulfhydryl-disulfide interchange, aggregation and precipitation of the modified enzyme (24-26). In the other, the failure to recover the activity of the enzyme may by associated with the extensive oxidation of other residues. 

Glutathione helps to maintain the sulfhydryl groups of proteins in a reduced state. An enzyme, protein-disulfide reductase, catalyzes sulfhydryl disulfide interchanges between glutathione and proteins. The reductase is important in insulin breakdown and may catalyze the reassortment of disulfide bonds during polypeptide chain folding. 

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