Abstract:
The spectra of amide I region (1700-1600cm-1) of horse heart ferricytochrome c at
20oC are reported at low ionic strength at of pH values between 7.0 and 11.5 encompassing the
alkaline transition. The mid-infrared spectra can probe the protein secondary structures. The Fourier
transform infrared spectroscopic technique is used to investigate the changes in the
conformationally sensitive amide I band of cytochrome c with pH and ionic strength. Analysis of
these results supports the hypothesis that an increase in the non-repetitive secondary structure
during alkaline transition is at the expense of regular secondary structures. These strongly suggest
that structural switching and ligand exchange behaviour of ferricytochrome c is accompanied by
conformational change in the protein backbone.
