Interaction of an anticancer ruthenium complex HInd[RuInd2Cl4] with cytochrome c.

Cytochrome c is an important electron transfer protein in the respiratory chain, shuttling electrons from cytochrome c reductase to cytochrome c oxidase. Extensive chemical modification studies indicate significant electrostatic interactions between these proteins and show that all structural and conformational changes of cytochrome c can influence the electron transport. In the present work we examine the effect of an anticancer ruthenium complex, trans-Indazolium (bisindazole) tetrachlororuthenate(III) (HInd[RuInd(2)Cl(4)]), on the conformation of cytochrome c, the state of the heme moiety, formation of the protein dimer and on the folding state of apocytochrome c. For this purpose, gel-filtration chromatography, absorption second derivative spectroscopy, circular dichroism (CD) and inductively coupled plasma atomic emission spectroscopy (ICP(AES)) were used. The present data have revealed that binding of the potential anticancer drug HInd[RuInd(2)Cl(4)] complex to cytochrome c induces a conformation of the protein with less organized secondary and tertiary structure.