Cyanide binding to Cu,Zn superoxide dismutase: an NMR study of the Cu(II),Co(II)

Journal Article · Tue Jan 05 04:00:00 EST 1988 · J. Biol. Chem.; (United States)

OSTI ID:6837282

Paci, M; Desideri, A; Rotilio, G

The Cu,Co superoxide dismutase derivative, in which the native Zn(II) was replaced by Co(II), was investigated by /sup 1/H NMR spectroscopy at pH 7.0 in the presence of CN/sup -/ and N/sub 3//sup -/. Addition of either anion produced large but remarkably different variations in the position of the histidine proton signals bound to the metal cluster. The resonances of the histidines bound to the copper broadened at low CN/sup -/ concentrations and narrowed again, with changed chemical shifts at (KCN) > 10/sup -2/ M. At 7 /sup 0/C two resonances split into two pairs of lines as a function of (CN/sup -/). The temperature dependence of these resonances, in the presence of nonsaturating (CN/sup -/), suggests a slow exchange between two forms of the protein-bound copper in the presence of the anion. The apparent activation parameters associated with the interconversion of the two species indicate a local conformational change in the presence of CN/sup -/. No evidence of temperature dependence was seen in the spectrum in the presence of N/sub 3//sup -/, which, on the other hand, was fully removed from the copper by addition of CN/sup -/. No evidence was obtained for removal by CN/sup -/ of a histidine bound to the copper as previously reported for low affinity anions at pH 5.5. These results indicate that CN/sup -/ has a unique pattern of binding to the enzyme copper. Since catalytic and structural data indicate that CN/sup -/ is the only appropriate substrate analogue for the Cu,Zn superoxide dismutase, data from anions with much less affinity may lead to misleading conclusions on the mechanism of anion and substrate binding to the enzyme.

• Research Organization: Tor Vergata Univ. via O. Raimondo, Rome (Italy)
• OSTI ID: 6837282
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 263:1; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

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59 BASIC BIOLOGICAL SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
ANIONS
BARYONS
BIOCHEMICAL REACTION KINETICS
CHARGED PARTICLES
COBALT COMPOUNDS
CONFIGURATION INTERACTION
COPPER COMPOUNDS
CYANIDES
ELEMENTARY PARTICLES
ENZYMES
FERMIONS
HADRONS
IONS
KINETICS
MAGNETIC RESONANCE
NUCLEAR MAGNETIC RESONANCE
NUCLEONS
OXIDOREDUCTASES
PROTONS
REACTION KINETICS
RESONANCE
SUPEROXIDE DISMUTASE
TRANSITION ELEMENT COMPOUNDS
ZINC COMPOUNDS