Cysteine modification

Kurose, K., Inouye, S., Sakaki, Y., and Tsuji, F. I. (1989). Bioluminescence of the calcium-binding photoprotein aequorin after cysteine modification. Proc. Natl. Acad. Sci. USA 86 80-84. 

Thus, iodoacetamide has the highest reactivity toward cysteine sulfhydryl residues and may be directed specifically for —SH blocking. If iodoacetamide is present in limiting quantities (relative to the number of sulfhydryl groups present) and at slightly alkaline pH, cysteine modification will be the exclusive reaction. For additional information on a-haloacetate reactivities and a protocol for blocking, see Section 4.2 (this chapter). 

Marcus, S., Caldwell, G.A., Miller, D., Xue, C.B., Naider, F., and Becker, J.M. (1991). Significance of C-terminal cysteine modifications to the biological activity of the Saccharomyces cerevisiae a-factor mating pheromone. Mol Cell Biol 11 3603-3612. 

The results of cysteine modification confirm the similarities in structure and function of the active sites of mammalian and yeast alcohol dehydrogenases (Section II,D). Minor differences are, however, observed. Thus, the nicotinamide-substituted imidazole dinucleotide (137) selectively alkylates one of the two cysteine ligands to the catalytic zinc atom, Cys-43, in the yeast enzyme. In the horse enzyme, on the other hand, the same reagent alkylates a different ligand to the same zinc atom, Cys-174. 

Fig. 10.3-2 Common strategies for protein bioconjugation, targeting lysine, cysteine, aspartic acid, and glutamic acid residues. In most situations, only cysteine modification reactions are site selective.

Various organocatalyst-based hybrid catalysts were also prepared in this study [61]. For example, flavin 24 was used for the selective cysteine modification of the tHisF mutant Cys9Ala/AspllCys. This compound allows for direct quantification of chemical modification because it has chromophoric properties. In view of future en masse parallelized bioconjugation of mutant libraries in the process of directed evolution experiments (Fig. 3), the course of the chemical modification process was studied more... 

Levonen AL, Landar A, Ramachandran A, Ceaser EK, Dickinson DA, Zanoni G, Morrow JD, Darley-Usmar VM (2004) Cellular mechanisms of redox cell signalling role of cysteine modification in controlling antioxidant defences in response to electrophilic lipid oxidation products. Biochem J 378(Pt 2) 373-382... 

An instractive example of the effect of cysteine modification on amyloid formation is provided by the TTR protein. This plasma protein is a tetramer in solution, with four identical 127 amino acid sub-units and is responsible for transport of thyroxine and the retinol-binding protein-vitamin A complex (Hamilton and Benson 2001). Deposition of wtTTR occurs in senile systemic amyloidosis (SSA) (Table 1). This is a non-hereditary disorder that affects roughly 25% of individuals over the age of 80. The amyloid fibrils formed consist mainly of wfTTR and its fragments, and they build up in the heart. 

C., Mussgnug, J.H., Nickelsen, J., and Kruse, O. (2009) Cysteine modification of a specific repressor protein controls the translational status of nucleus-encoded LHCII mRNAs in Chlamydomonas. Proc. Natl. Acad. Sci. U.S.A., 106 (32), 13290-13295,... 

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