/sup 31/P NMR study of the interaction of inorganic phosphate with bovine copper-zinc superoxide dismutase

Journal Article · Wed Aug 26 04:00:00 EDT 1987 · Inorg. Chem.; (United States)

DOI:https://doi.org/10.1021/ic00264a014· OSTI ID:5572262

de Freitas, D M; Luchinat, C; Banci, L; Bertini, I; Valentine, J S

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), Journal Name: Inorg. Chem.; (United States) Vol. 26:17; ISSN INOCA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400202 -- Isotope Effects
Isotope Exchange
& Isotope Separation
CHEMICAL REACTIONS
COPPER COMPOUNDS
DATA
ENZYMES
EXPERIMENTAL DATA
INFORMATION
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS 31
PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
RADICALS
RESONANCE
STABLE ISOTOPES
SUPEROXIDE RADICALS
TRANSITION ELEMENT COMPOUNDS
ZINC COMPOUNDS