/sup 31/P NMR study of the interaction of inorganic phosphate with bovine copper-zinc superoxide dismutase
Paramagnetic effect of /sup 31/P phosphate resonances caused by Cu(II) ions in native and phenylglyoxal-modified bovine Cu,Zn-superoxide dismutase have been used to monitor the interaction of phosphate with these proteins. T/sub 2/ values are found to be 70 times smaller than T/sub 1/, indicating that some mechanisms, as yet undefined, contribute to the line width. Using T/sub 1/ measurements, it was determined that the affinity constants for phosphate binding to the native protein are 20 +/- 4 and 34 +/- 3 M/sup -1/ at pH 8.0 and 7.0 respectively, and that the Cu(II)-phosphate distance 5.3 A. At pH 6.3, two binding sites are observed, one at a distance >7 A with an affinity constant >100 M/sup -1/ and another at approximately 5 A with an affinity constant of 10 M/sup -1/. Modification of the protein with phenylglyoxal causes the affinity of phosphate for the same sites to decrease by a factor of 3 at pH 6.3. These results indicate that phosphate does not bind directly to Cu(II) but to a site close by. It was concluded that the site of phosphate binding is Arg-141, which in known from X-ray structural evidence to be located approximately 5 Angstrom form the copper center. 26 references, 4 figures.
- Research Organization:
- Loyola Univ. of Chicago, IL
- OSTI ID:
- 5572262
- Journal Information:
- Inorg. Chem.; (United States), Vol. 26:17
- Country of Publication:
- United States
- Language:
- English
Similar Records
Cyanide binding to Cu,Zn superoxide dismutase: an NMR study of the Cu(II),Co(II)
Characterization of copper-nickel and silver-nickel bovine superoxide dismutase by /sup 1/H NMR spectroscopy
Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
COPPER COMPOUNDS
CHEMICAL REACTIONS
NUCLEAR MAGNETIC RESONANCE
ENZYMES
PHOSPHATES
SUPEROXIDE RADICALS
ZINC COMPOUNDS
EXPERIMENTAL DATA
PHOSPHORUS 31
DATA
INFORMATION
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
RADICALS
RESONANCE
STABLE ISOTOPES
TRANSITION ELEMENT COMPOUNDS
400201* - Chemical & Physicochemical Properties
400202 - Isotope Effects
Isotope Exchange
& Isotope Separation