Magnetic circular dichroism spectroscopy as a probe of axial heme ligand replacement in semisynthetic mutants of cytochrome c

FEBS Letters

Dawson, John H.¹  Rux, John J.¹ 

[1] Department of Chemistry, University of South Carolina, Columbia, SC 29208, USA

关键词: MCD spectroscopy;    Active site structure determination;    Cytochrome;    Cysteine ligation;    Histidine ligation;    Electron transfer protein;    EPR;    electron paramagnetic resonance;    MCD;    magnetic circular dichroism;    P-450;    cytochromes P-450 from any source;    P-450-CAM;    the camphor-hydroxylating P-450 from Pseudomonas putida;    cyt c-Cys80;    cytochrome c having cysteine as an axial ligand in place of methionine at position 80;    cyt c-His80;    cytochrome c having histidine in place of methionine at position 80;    cyt c-Imid;    the imidazole adduct of cytochrome c with imidazole in place of methionine;   

DOI  :  10.1016/0014-5793(91)81222-T

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Horse heart cytochrome c with either histidine or cysteine replacing the endogenous axial methionine ligand at position 80 has been characterized with magnetic circular dichroism (MCD) spectroscopy in the UV-visible region. Comparison of the MCD spectra of the mutant proteins in the ferric state to those of authentic bis-imidazole- and imidazole/thiolate-ligated ferric heme proteins clearly shows that the histidine-imidazole and cysteine-thiolate groups of the replacement amino acids at position 80 are coordinated to the heme iron in the mutant proteins. This study demonstrates the power of MCD spectroscopy in identifying axial ligands in mutant heme proteins. Accurate axial ligand assignment is essential for proper interpretation of the altered properties of such novel proteins.

【 授权许可】

Unknown