Cysteine , genetically engineered residue

Some recent approaches to orientated immobilization exploited methods of genetic engineering to introduce suitable binding site like a cysteine residue [101]. Mansfeld and Ulbrich-Hofmann introduced cysteine on a thermolysinelike neutral protease from Bacillus stearothermophilus [114]. This approach is especially interesting since it allows the introduction of cystein residues in different positions of the protein molecule and therefore enables one to study the effects of molecule orientation on its biological activity [115]. More information about the oriented immobilization can be found in recent reviews of Turkova [101,110]. 

J. C. Lewis and S. Daunert, Bioluminescence Immunoassay for Thyroxine Employing Genetically Engineered Mutant Aequorins Containing Unique Cysteine Residues, Anal. Chem. 2001, 732, 3227. 

Similarly, the wild type of CCMV could be chemically derivatized using amine-reactive fluorescent anhydrides or via activation of surface-exposed carboxylates and subsequent reaction with fluorophores bearing nucleophilic amine groups. In addition, genetically engineered CCMV with surface-exposed cysteine residues could be used for additional thiol selective attachment of fluorophores and peptides. 

A cytochrome P450 j j mutant genetically engineered so as to introduce a surface cysteine residue at position 344 was labeled with the related compound N-ferro-cenyl maleimide 25. 

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