Effect of polyanions on ferricytochrome c.

Effects of two polyanions (heparin, Nafion) on absorption and CD spectra in the Soret region, and on fluorescence of ferricytochrome c were investigated. The conformational state of ferricyt c in the complexes with studied polyanions is significantly different. Whereas heparin affects the structure in the heme region of ferricyt c only slightly (ferricyt c remains in a native-like state), the influence of Nafion is more expressive (the Met-80-heme iron bond and the deeply buried region around Trp-59 are perturbed). Shift of the pK of the transition from neutral low-spin state to acidic high-spin state to higher pH values was observed.