Aromatic residues in c-type cytochromes might have an important function in the folding and/or electron transferring properties of the molecule. In the tetraheme cytochrome c3 (Mr 13 000) from Desulfovibrio vulgaris Hildenborough, Phe20, is located between heme 1 and heme 3 with its aromatic ring close and almost parallel to the ring plane of heme 1. We replaced this residue by a nonaromatic hydrophobe residue, leucine, and analyzed the effects in terms of functional, structural, and physicochemical properties. While the F20L replacement did not have any strong effects on the heme region stability, a decrease of the thermostability of the whole molecule was observed. In the same way, the four macroscopic redox potentials were affected by the mutation as well as the flexibility of the surface loop around heme 4. The F20L replacement itself and/or this structural modification might be responsible for the loss of the intermolecular cooperativity between F20L cytochrome c3 molecules. Study holds ProTherm entries: 16307, 16308 Extra Details: The partial molar heat capacity at 20 C is 3.8 kcal/K mol. cytochrome c3, mutagenesis, heme region stability, phenylalanine 20
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:47 p.m.
|Number of data points||3|
|Proteins||Cytochrome c3 ; High-molecular-weight cytochrome c|
|Assays/Quantities/Protocols||Experimental Assay: Tm ; Derived Quantity: dTm|
|Libraries||Mutations for sequence APKAPADGLKMEATKQPVVFNHSTHKSVKCGDCHHPVNGKEDYRKCGTAGCHDSMDKKDKSAKGYYHVMHDKNTKFKSCVGCHVEVAGADAAKKKDLTGCKKSKCHE|