Drastic Influence of a Single Heme Axial Ligand Replacement on the Thermostability of Cytochrome c3

• Published in: Biochemical and biophysical research communications Vol. 211; no. 3; pp. 742 - 747
• Main Authors: Dolla, A., Florens, L., Bruschi, M., Dudich, I.V., Makarov, A.A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 26-06-1995
• Subjects: Circular Dichroism; Cytochrome c Group - chemistry; Cytochrome c Group - genetics; Desulfovibrio vulgaris - chemistry; Desulfovibrio vulgaris - genetics; Histidine - chemistry; Histidine - genetics; Hot Temperature; Ligands; Methionine - chemistry; Methionine - genetics; Point Mutation; Protein Denaturation; Spectrophotometry, Ultraviolet
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.1995.1875

The thermostability of wild type Desulfovibrio vulgaris Hildenborough tetraheme cytochrome c3 and its H22M, H25M, H35M and H70M mutants was studied by circular dichroism technique in the far UV and Soret regions. It was shown that wild type cytochrome is extremely thermostable and retains structural and functional properties up to 110°C. Mutations do not change overall secondary structure and local structure of the hemes vicinity. All mutants are much more unstable to heat denaturation than the wild type cytochrome. Point mutation (His/Met replacement) results in extraordinary 30-45°C decrease in the protein thermostability depending on the mutation. We may conclude therefore that the heme region is important not only for the functional properties of the cytochrome but also for the overall protein thermostability.