Proteins Undergoing Folding-Defolding Processes

Particularly relevant to this chapter is work done on protein folding triggered by electron transfer. This electron transfer step can be either electrochemical181 or photochemical using such means as Ru(bipy) + in its 3MLCL excited state as an elec- 

Addition of increasing concentrations of guanidinium chloride favors the unfolded form of ferri cyt c (Fe(m)), due to binding to the iron center by chloride. 

Reversible chemical oxidation reactions have also been used to control and modulate the conformation of polypeptide chains.119,101 By converting methionine to its sulfoxide, Gellman and co-workers were able to control the secondary structure of an 18-residue peptide. The side chain of a methionine residue (containing a CH2CH2SCH3 fragment) is hydrophobic and favors a-helical folding. Oxidation to the methionine sulfoxide state results in a preference for a (i-strand situation. 

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