Azide binding to yeast cytochrome c peroxidase and horse metmyoglobin: comparative thermodynamic investigation using isothermal titration calorimetry

2004 ◽  
Vol 422 (2) ◽  
pp. 125-136 ◽  
Author(s):  
Timothy Jacobson ◽  
Joy Williamson ◽  
Anthony Wasilewski ◽  
Janet Felesik ◽  
Lidia B. Vitello ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Isothermal Titration Calorimetry ◽  
Cytochrome C Peroxidase ◽  
Titration Calorimetry ◽  
Thermodynamic Investigation ◽  
Azide Binding

Binding of Yeast Cytochrome c to Forty-Four Charge-Reversal Mutants of Yeast Cytochrome c Peroxidase: Isothermal Titration Calorimetry

Biochemistry ◽  
2015 ◽  
Vol 54 (31) ◽  
pp. 4845-4854 ◽  
Author(s):  
James E. Erman ◽  
Lidia B. Vitello ◽  
Naw May Pearl ◽  
Timothy Jacobson ◽  
Meka Francis ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Isothermal Titration Calorimetry ◽  
Cytochrome C Peroxidase ◽  
Titration Calorimetry ◽  
Charge Reversal

scholarly journals Thermodynamics of hydrogen cyanide and hydrogen fluoride binding to cytochrome c peroxidase and its Asn-82→Asp mutant

1994 ◽  
Vol 302 (2) ◽  
pp. 437-442 ◽  
Author(s):  
S F DeLauder ◽  
J M Mauro ◽  
T L Poulos ◽  
J C Williams ◽  
F P Schwarz
Keyword(s):  
Cytochrome C ◽  
Binding Constant ◽  
Binding Constants ◽  
Cytochrome C Peroxidase ◽  
Titration Calorimetry ◽  
Difference Spectroscopy ◽  
Cyanide Binding ◽  
Order Of Magnitude ◽  
Binding Enthalpy ◽  
Entropic Effects

The thermodynamics of binding of fluoride and cyanide to cytochrome c peroxidase (CCP) and its Asn-82-->Asp mutant (D82CCP) in phosphate and acetate buffer at an ionic strength of 0.15 mol.kg-1 from pH 5.0 to 7.1 were investigated by titration calorimetry at 289 and 297 K. The binding reactions are enthalpically driven. The fluoride-binding constants determined from the titration calorimetry results were in agreement with those determined from difference-spectroscopy measurements. For cyanide binding to CCP at 297.9 K, the binding constant decreased from 8.95 (+/- 0.83) x 10(5) M-1 at pH 7.0 to 4.04(+/- 0.23) x 10(5) M-1 at pH 5.0, and the binding enthalpy increased from -57.2 +/- 1.4 kJ.mol-1 at pH 7.0 to -48.6 +/- 1.8 kJ.mol-1 at pH 5.0. For fluoride binding to CCP, the binding constant increased from 8.41(+/- 0.54) x 10(3) M-1 at pH 7.0 to 3.11(+/- 0.09) x 10(5) M-1 at pH 5.0 and the binding enthalpy increased from -71.9 +/- 1.1 kJ.mol-1 at pH 7.0 to -67.0 +/- 1.9 kJ.mol-1 at pH 5.0. The binding enthalpies for D82CCP were about the same as those for CCP. However, the binding constants for cyanide and fluoride to D82CCP were respectively a factor of two less and at least an order of magnitude less than the corresponding binding constants of CCP. Decreased ligand-binding strength in the D82CCP mutant is thus entirely due to entropic effects.

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