Maleimide reactive cross-linkers

The first two compounds discussed in this section are truly sulfhydryl-reactive, using the common iodoacetyl and maleimide functionalities, respectively. The third derivative, however, is not reactive directly with sulfhydryl groups, but contains a protected sulfhydryl which, after deprotection, can be used to react with other sulfhydryl-reactive cross-linkers. 

The most common type of heterobifunctional reagent used for the activation of lipid components includes the amine- and sulfhydryl-reactive cross-linkers containing an NHS ester group on one end and a maleimide, iodoacetyl, or pyridyl disulfide group on the other end (Chapter 5, Section 1). Principle reagents used to effect this activation process include SMCC (Chapter 5, Section 1.3), MBS (Chapter 5, Section 1.4), SMPB (Chapter 5, Section 1.6), SIAB (Chapter 5, Section 1.5), and SPDP (Chapter 5, Section 1.1). 

Creation of a sulfhydryl-reactive PEG derivative was done by Goodson and Katre (1990) by reacting a active ester—maleimide heterobifunctional cross-linker with the... 

Benzophenone-4-maleimide is a heterobifunctional photoreactive cross-linker that has sulfhydryl reactivity similar to benzophenone-4-iodoacetamide discussed in the... 

Figure 287 Carrier proteins may be activated with sulfo-SMCC to produce maleimide derivatives reactive with sulfhydryl-containing molecules. The graphs show the gel filtration separation on Sephadex G-2S of maleimide-activated BSA (A) and OVA (B) after reaction with sulfo-SMCC. The first peak is the protein and the second peak is excess cross-linker. The maleimide groups create increased absorbance at 280 nm in the activated proteins.

Succinimidyl-4-(p-maleimidophenyl)butyrate (SMPB) is a heterobifunctional analog of MBS containing an extended cross-bridge (Chapter 5, Section 1.6). The cross-linker has an amine-reactive NHS ester on one end and a sulfhydryl-reactive maleimide group on the other. Conjugates formed using SMPB thus are linked by stable amide and thioether bonds. 

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