Temperature, pH, and solvent isotope effects on cytochrome c peroxidase mutant N82A studied by proton NMR.
The mutant of baker's yeast cytochrome c peroxidase-CN with Ala82 in place of Asn82, [N82A]CcPCN, exhibits a complex solution behavior featuring dynamic interconversion among three enzyme forms that so far have only been detected by NMR spectroscopy. Proton NMR studies of [N82A]CcPCN reveal resonances from each of the three enzyme forms and show that the interconversion among forms is controlled by the pH, temperature, and isotope composition (H2O vs. D2O) of the buffer solution. No evidence for a key hydrogen bond between His52 and heme-coordinated cyanide is found in any of the enzyme forms, indicating that disruption of the extensive distal hydrogen bonding network is the source of this phenomenon.
Satterlee
J D
JD
Department of Chemistry, Washington State University, Pullman 99164-4630, USA. heme.team@wsu.edu
Teske
J G
JG
Erman
J E
JE
Mauro
J M
JM
Poulos
T L
TL
D000409:Alanine / Q000737:chemistry / Q000235:genetics; D019943:Amino Acid Substitution; D001216:Asparagine / Q000737:chemistry / Q000235:genetics; D003578:Cytochrome-c Peroxidase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D012997:Solvents; D013696:Temperature; D013816:Thermodynamics
D012997:Solvents; D001216:Asparagine; D003578:Cytochrome-c Peroxidase; D000409:Alanine