Effect of redox state on unfolding energetics of heme proteins.
Both the enthalpic and entropic contributions to unfolding of three heme proteins, cytochrome b(562), cytochrome c and myoglobin, are larger for the reduced than for the oxidized form. Thus, the higher thermodynamic stability of a reduced, as compared to an oxidized, heme protein is the net result of a large increase of favorable enthalpy and a small increase in unfavorable entropy. Upon comparing the unfolding energetics of the heme proteins to those of other single-domain proteins I find that protein length is the primary determinant of the thermodynamics.
Chemistry Department, Tulane University, 6823 St. Charles Ave., New Orleans, LA 70118-5698, USA. pernilla@mailhost.tcs.tulane.edu
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D003573:Cytochrome b Group / Q000737:chemistry; D003574:Cytochrome c Group / Q000737:chemistry; D029968:Escherichia coli Proteins; D006420:Hemeproteins / Q000737:chemistry*; D009211:Myoglobin / Q000737:chemistry; D010084:Oxidation-Reduction; D017510:Protein Folding; D013696:Temperature; D013816:Thermodynamics
D003573:Cytochrome b Group; D003574:Cytochrome c Group; D029968:Escherichia coli Proteins; D006420:Hemeproteins; D009211:Myoglobin; C017850:cytochrome b562, E coli