The chemical denaturation of Pseudomonas aeruginosa cytochrome c(551) variants was examined at pH 5.0 and 3.6. All variants were stabilized at both pHs compared with the wild-type. Remarkably, the variants carrying the F34Y and/or E43Y mutations were more stabilized than those having the F7A/V13M or V78I ones at pH 5.0 compared with at pH 3.6 by ~3.0-4.6 kJ/mol. Structural analyses predicted that the side chains of introduced Tyr-34 and Tyr-43 become hydrogen donors for the hydrogen bond formation with heme 17-propionate at pH 5.0, but less efficiently at pH 3.6, because the propionate is deprotonated at the higher pH. Our results provide an insight into a stabilization strategy for heme proteins involving variation of the heme electronic state and introduction of appropriate mutations. Study holds ProTherm entries: 24920, 24921, 24922, 24923, 24924, 24925, 24926, 24927, 24928, 24929, 24930, 24931, 24932, 24933, 24934, 24935, 24936, 24937, 24938, 24939 Extra Details: Circular dichroism spectroscopy; Cytochrome c; Hydrogen bond; Protein stability; Heme propionate
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:55 p.m.
|Number of data points||78|
|Proteins||Cytochrome c-551 ; Cytochrome c-551|
|Assays/Quantities/Protocols||Experimental Assay: Cm pH:3.6 ; Experimental Assay: m pH:3.6 ; Experimental Assay: dG_H2O pH:3.6 ; Experimental Assay: Cm pH:5.0 ; Experimental Assay: m pH:5.0 ; Experimental Assay: dG_H2O pH:5.0 ; Derived Quantity: ddG_H2O pH:3.6 ; Derived Quantity: ddG_H2O pH:5.0|
|Libraries||Mutations for sequence EDPEVLFKNKGCVACHAIDTKMVGPAYKDVAAKFAGQAGAEAELAQRIKNGSQGVWGPIPMPPNAVSDDEAQTLAKWVLSQK|