Conformational Change of Wild Type Cytochrome c Characterized by NMR Spectroscopy at Natural Isotropic Abundance

Abstract

Cytochrome c is an important multifunctional protein, which plays important roles in the respiratory chain and cell apoptosis. Characterization of conformational changes of cytochrome c is essential to elucidate the molecular mechanism underlying its functions. Isotope-labeled proteins are usually needed for nuclear magnetic resonance (NMR)-based protein structure elucidation. However, post-translational modification of cytochrome c makes it difficult to be labelled by isotopes. In this work, 1H-13C HSQC NMR experiment was used to characterize the conformational changes of naturally purified wild-type cytochrome c in the redox process, focusing on the side chain methyl groups. It was observed that this method could detect the signals of most methyl groups within 2 h, and the methyl groups detected with apparent chemical shift change were coincide with its conformation change. The results indicated that it is possible to use the method proposed to study the conformational changes of proteins at natural abundance or post-translational modified proteins.

Keywords

• nuclear magnetic resonance (nmr)
• conformational change
• 1h-13c hsqc
• cytochrome c