sup 35 Cl and sup 1 H NMR study of anion binding to reduced bovine copper-zinc superoxide dismutase

Journal Article · Wed Sep 05 04:00:00 EDT 1990 · Inorganic Chemistry; (USA)

DOI:https://doi.org/10.1021/ic00343a045· OSTI ID:6170448

Mota de Freitas, D; Ramasamy, R ^[1]; Ming, Lijune; Valentine, J S ^[2]

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1. Loyola Univ. of Chicago, IL (USA)
2. Univ. of California, Los Angeles (USA)

Binding of chloride to reduced bovine copper-zinc superoxide dismutase (Cu{sub 2}Zn{sub 2}SOD) and chemically modified derivatives was monitored by the line width at half-height of the Cl{sup {minus}} resonance as measured by {sup 35}Cl nuclear magnetic resonance (NMR) spectroscopy. Reduced arginine-modified and reduced lysine-modified Cu{sub 2}Zn{sub 2}SOD (at concentrations of 2.14 {times} 10{sup {minus}4} M) caused less broadening of the Cl{sup {minus}} resonance line width of 0.1 M NaCl solutions than did reduced native protein when measured under the same conditions; Cl{sup {minus}} broadening with all protein derivatives decreased drastically in the presence of 0.05 M phosphate. The C-H and N-H proton resonances of histidyl imidazoles of reduced native and reduced lysine-modified Cu{sub 2}Zn{sub 2}SOD were shifted by addition of Cl{sup {minus}} (with apparent affinity constants of 12 and {approximately} 2 M{sup {minus}1}, respectively) whereas this anion had less effect in the {sup 1}H NMR spectrum of reduced arginine-modified Cu{sub 2}Zn{sub 2}SOD (affinity constant <2 M{sup {minus}1}) under the same conditions. phosphate caused relatively smaller changes on the {sup 1}H NMR resonances of all reduced protein derivatives. The competition measured by {sup 1}H NMR spectroscopy between chloride and phosphate for anion binding sites in the neighborhood of the Cu{sup 1} ion was much less than that for nonspecific Cl{sup {minus}} binding monitored by {sup 35}Cl NMR spectroscopy. It is concluded from these experiments that, in addition to the weak anion binding at or near the Cu{sup I} ion, Arg-141, Lys-120, and Lys-134 serve as major anion binding sites in the reduced native protein. 57 refs., 5 figs., 2 tabs.

• OSTI ID: 6170448
• Journal Information: Inorganic Chemistry; (USA), Journal Name: Inorganic Chemistry; (USA) Vol. 29:18; ISSN 0020-1669; ISSN INOCA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical &amp; Physicochemical Properties
400202 -- Isotope Effects
Isotope Exchange
&amp; Isotope Separation
550200 -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
BARYONS
CHEMICAL PREPARATION
CHLORINE 35
CHLORINE COMPOUNDS
CHLORINE ISOTOPES
COPPER COMPOUNDS
DATA
ELEMENTARY PARTICLES
ENZYMES
EXPERIMENTAL DATA
FERMIONS
HADRONS
HALOGEN COMPOUNDS
INFORMATION
ISOTOPES
LIGHT NUCLEI
NMR SPECTRA
NUCLEI
NUCLEONS
NUMERICAL DATA
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
OXIDOREDUCTASES
PROTONS
SPECTRA
STABLE ISOTOPES
SUPEROXIDE DISMUTASE
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
ZINC COMPOUNDS