Thiol-maleimide conjugation, protein

Add the thiol-protein to the maleimide-PEG-protein in the desired molar ratio to initiate the conjugation reaction. 

Figure 7.10 An NHS-PEG-maleimide compound can be used to functionalize dendrimers to provide a hydrophilic spacer terminating in thiol-reactive groups. Thiol-containing proteins then can be conjugated to this reactive intermediate to form covalent thioether bonds.

Figure 19.16 A common way of conjugating sulfhydryl-containing haptens to carrier proteins is to activate the carrier with sulfo-SMCC to create an intermediate maleimide derivative. The maleimide groups then can be coupled to thiols to form thioether bonds.

OPDM). One of two maleimide residues of OPDM, added in excess (10 pM) to the protein, reacts with the thiol group, whereas the other remains inactive. The number of maleimide-reacted thiol groups in the protein can be estimated by the determination of the number of unmodified sulfhydryl groups. Subsequently, the maleimide-deri-vatized protein is conjugated with BGase. 

Maleimides (Section 11.2.3.2.1.2) are particularly useful for the conjugation of thiol-containing haptens. Other approaches are based on the activation of the protein with bromoacetamide groups (Singh et al., 1978) or on the formation of disulfide bonds between the carrier and hapten in acetate buffer, pH 4.0, in the presence of hydrogen peroxide, as used for the conjugation of penicillenic acid (De Week and Eisen, 1960). 

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