Maleimide reactivity

React the protein with activated dendrimer for 2 hours at room temperature with mixing. At the completion of the reaction, cysteine may be added at 50 mM to block excess maleimide-reactive sites, which are not coupled with protein. 

Other heterobifunctional crosslinkers with NHS and maleimide reactive groups (e.g., BMPS, MBS, SMCC) can be used in place of GMBS. The final concentration of these other linkers in the ethanolic mix should be 1 mM. 

Polymerization by Gycloaddition. Bisimides and oligoimides capped with reactive unsaturations such as maleimide, acetylene, and xylylene groups, can be chain-extended by a cycloaddition reaction with proper bisdienes. 

Dihydropyridines 8 react with dienophiles such as A -phenyl maleimide (2) and l,2,4-triazoline-3,5-dione 9 to give the Diels-Alder adducts 10 and 11, respectively (76JHC481). Fowler observed that when a mixture of 1,2- and 1,4-dihydropyridines was treated with maleic anhydride (12), only 1,2-dihydro-pyridines yielded the Diels-Alder adducts 13, whereas the 1,4-dihydropyridines showed no reactivity with 12 (72JOC1321) (Scheme 1). 

The more reactive furan (139a) undergoes thermal Diels-Alder reaction [52] with reactive dienophiles such as maleic anhydride and maleimide (Scheme 5.21). Whereas the cycloaddition with the maleic anhydride afforded the exoadduct at room temperature, the stereochemistry of the reaction of maleimide depends on the reaction temperature. 

Maleimides Alkyl and aryl maleimides in small concentrations, e.g., 5-10 wt% significantly enhance yield of cross-link for y-irradiated (in vacuo) NR, cw-l,4-polyisoprene, poly(styrene-co-butadiene) rubber, and polychloroprene rubber. A-phenyhnaleimide and m-phenylene dimaleimide have been found to be most effective. The solubihty of the maleimides in the polymer matrix, reactivity of the double bond and the influence of substituent groups also affect the cross-fink promoting ability of these promoters [82]. The mechanism for the cross-link promotion of maleimides is considered to be the copolymerization of the rubber via its unsaturations with the maleimide molecules initiated by radicals and, in particular, by allyfic radicals produced during the radiolysis of the elastomer. Maleimides have also been found to increase the rate of cross-linking in saturated polymers like PE and poly vinylacetate [33]. 

An affinity label is a molecule that contains a functionality that is chemically reactive and will therefore form a covalent bond with other molecules containing a complementary functionality. Generally, affinity labels contain electrophilic functionalities that form covalent bonds with protein nucleophiles, leading to protein alkylation or protein acylation. In some cases affinity labels interact selectively with specific amino acid side chains, and this feature of the molecule can make them useful reagents for defining the importance of certain amino acid types in enzyme function. For example, iodoacetate and A-ethyl maleimide are two compounds that selectively modify the sulfur atom of cysteine side chains. These compounds can therefore be used to test the functional importance of cysteine residues for an enzyme s activity. This topic is covered in more detail below in Section 8.4. 

BMPA is N-(3-maleimidopropionic acid (or 3-maleimidopropionic acid), which contains a thiol-reactive maleimide group at one end and a carboxylate group on the other end (Rich et al., 1975 Moroder, 1983, 1987). The compound is the acid precursor to the short, heterobifunctional crosslinker 3-maleimidopropionic acid N-hydroxysuccinimide ester (BMPS). 

Reactive double bonds are capable of undergoing addition reactions with sulfhydryl groups. A popular example of this type of functional group is the maleimide group (Section 2.2, this... 

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