Biomaterial Database

Superoxide dismutase. Reversible removal of manganese and its substitution by cobalt, nickel or zinc. 1976

D E Ose, and I Fridovich

The maganese-containing superoxide dismutase, from Escherichia coli, lost metal and activity when dialyzed against 20 mM-8-hydroxyquinoline and 2.5 M guanidinium chloride in 5 mM Tris-chloride buffer at pH 7.8. Subsequent dialysis against 0.01 m M McCl2, in this buffer, caused a restoration of manganese and activity. Reconstituted enzyme appeared identical with native enzyme, and removal and restoration of manganese could be repeated. Co (II), Zn(II), Ni(II), Mg(II), Cr (II), Cu(II), Fe(II), In(II), and Mo(VI), were tested for their abiltiy to replace manganese. None of these restored activity to apoenzyme. When present at a 100-fold molar excess over manganese only Co(II), Ni(II), and Zn(II) were effective as competitors of manganese. Co(II) was demonstrated to be tightly bound to the apoenzyme in place of the magnasese, with a stoichiometry of 1 Co(II) per molecule. In the cases of Co(II), Zn(II), or Ni(II), reconstituted enzyme; the metals could be removed and subsequently replaced by manganese, with restoration of catalytic activity. None of these metal cations exhibited superoxide dismutase activity. We conclude that manganese is essential for the catalytic activity of superoxide dismutase, and that the site which normally binds manganese can accommodate Co(II), Ni(II), and Zn(II).

UI	MeSH Term	Description	Entries
D008345	Manganese	A trace element with atomic symbol Mn, atomic number 25, and atomic weight 54.94. It is concentrated in cell mitochondria, mostly in the pituitary gland, liver, pancreas, kidney, and bone, influences the synthesis of mucopolysaccharides, stimulates hepatic synthesis of cholesterol and fatty acids, and is a cofactor in many enzymes, including arginase and alkaline phosphatase in the liver. (From AMA Drug Evaluations Annual 1992, p2035)
D009532	Nickel	A trace element with the atomic symbol Ni, atomic number 28, and atomic weight 58.69. It is a cofactor of the enzyme UREASE.
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D002413	Cations, Divalent	Positively charged atoms, radicals or groups of atoms with a valence of plus 2, which travel to the cathode or negative pole during electrolysis.	Divalent Cations
D002857	Chromium	A trace element that plays a role in glucose metabolism. It has the atomic symbol Cr, atomic number 24, and atomic weight 52. According to the Fourth Annual Report on Carcinogens (NTP85-002,1985), chromium and some of its compounds have been listed as known carcinogens.
D003035	Cobalt	A trace element that is a component of vitamin B12. It has the atomic symbol Co, atomic number 27, and atomic weight 58.93. It is used in nuclear weapons, alloys, and pigments. Deficiency in animals leads to anemia; its excess in humans can lead to erythrocytosis.	Cobalt-59,Cobalt 59
D004789	Enzyme Activation	Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.	Activation, Enzyme,Activations, Enzyme,Enzyme Activations
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D001051	Apoenzymes	The protein components of enzyme complexes (HOLOENZYMES). An apoenzyme is the holoenzyme minus any cofactors (ENZYME COFACTORS) or prosthetic groups required for the enzymatic function.	Apoenzyme
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining