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At least 19 recordsLinked to original sources
PubMed1978

[Redox potentials of some metalloproteins].

The standard redox potentials of soluble cytochromes c isolated from the green alga Chlorella and the blue-green algae Spirulina and Aphanezomenon were determined by potentiometric titration and found to be equal to +380 mB, +330 mB and +357 AB, respectively. The standard redox potentials of plastocyanin preparations from Pisum sativum and Atriplex leaves were also determined and found close to those of soluble cytochromes c, i. e. +395 mB and +375 mB, respectively. The metalloproteins studied were shown to belong to monoelectron carriers operating at the donor sites of photosystem I.

Chlorella↗
PubMed1979

Methionyl-tRNA synthetase of Escherichia coli. A zinc metalloprotein.

The native dimeric form of methionyl-tRNA synthetase of Escherichia coli contains two zinc atoms per dimer, one per subunit. The bound zinc is retained upon trypsin modification which yields a monomer with one zinc atom. The enzymatic activity of both the dimeric forms is reversibly inhibited by 1,10-phenanthroline but not by its non-chelating analogues. In addition, the native enzyme binds two Mn2+ per dimer with a binding constant of approx. 70 micron but no binding is observed with the trypsin-modified monomer.

Amino Acyl-tRNA Synthetases↗
PubMed1978

Fast electron transfer processes in cytochrome C and related metalloproteins.

Various free radicals formed on pulse radiolysis of aqueous solutions have been used to investigate the mechanisms of reduction of cytochrome(III) c by inter- and intramolecular electron transfer. The rapid formation of free radicals (t less than 1 mus) and their high reactivity with cytochrome (k approximately 10(8)(-5) x 10(10)M(-1)s(-1)) make such studies feasible. Reduction of cytochrome by free radicls is monitored by optical methods. Fast optical changes in the 1(-500)-mus region correspond to reduction of the iron center; whereas the slower changes in the 10(-500)-ms region are attributed to postreduction conformational changes. It has been concluded that the reduction path is mediated through the crevice and that no reduction intermediates are being formed.

Cytochrome c Group↗
PubMed1979

Additional pharmacological aspects of orgotein, a metalloprotein with superoxide-dismutase activity.

Orgotein is a copper- and zinc-containing protein with superoxide-dismutase activity which can be isolated from bovine liver and erythrocytes. The effects of this drug on adjuvant -induced arthritis in rats, and particularly on the changes in erythrocytes sedimentation rates and plasma fibrinogen levels induced by this experimental infection, were studied. Orgotein was also assayed on nystatin-induced paw edema, passive cutaneous anaphylaxis and Arthus reaction, in rats. Finally, studies on platelet aggregation and the prostaglandin system were conducted. Given at doses of 2.5 and 5 mg/kg i.p. for 14 days to arthritic rats, orgotein normalized the serum changes, inhibited the foot swelling and improved the performance time on the rotating bar. The drug reduced, after a single dose, the nystatin-induced edema, whilst it showed no effects on the immunological inflammations, platelet aggregation and prostaglandin system. The probable mechanism of action is discussed.

Animals↗
PubMed1977

[Effect of metalloproteins on the photochemical activity of chloroplasts treated with polyene antibiotics].

The effects of various metall-containing proteins (plastocyanin, plantacyanin, azurine and cytochromes of the f type) on the activity of photosystem I of chloroplasts, treated with polyene antibiotics, were studied. The inhibiting effect of the polyenes, surgumycin and philipin, was completely removed by an addition of copper-containing protein plastocyanin. No similar effect was exerted by other Cu-containing proteins--azurine and plantacyanin. The cytochromes of the f type isolated from the green algae chlorella, blue-green algae spiruline and aphanezomenone, having different electrophoretic properties, restored the activity of photosystem I of chloroplasts incubated with antibiotics in a different degree. Acid cytochrome f of chlorella restored the activity by 80--100%; less acid cytochrome f from spiruline-only by 50%. The least restoring effect was exerted by aphanezomenone cytochrome, which possesses some basic properties. The chloroplasts treatment with surgumycin did not affect the isolation of the terminal enzyme of the chloroplast electron-transporting chain of ferredoxin--NADP--reductase. Possible environment of plastocyanin in the chloroplast membrane and the mechanism of photosystem I restoration are discussed.

Anti-Bacterial Agents↗
PubMed1975

Studies on the conformational changes of metalloproteins induced by electrons in water-ethylene glycol solutions at low temperatures. III. Adrenal ferredoxin.

The reduction of adrenal ferredoxin (adrenodoxin) at low temperatures was investigated in order to separate local modifications of the active centre of the protein on its reduction, from the conformational transition which seems to accompany the change of the redox state of the irons; The ESR spectra of the states of the protein, where the reduced active centre is to be found by the "oxidized" conformation of the apoprotein, were obtained. The transition from the states of the protein to the state which occurs on its chemical reduction at room temperature was also investigated. The results of the work support the view that conformational changes in proteins (enzymes) which take place while they are functioning proceed after modifications of the active centres (change of the redox state, adsorption of a substrate, etc.), and are essentially caused by them. Adrenal ferredoxin was the third subject in our studies of the intermediate states of proteins which appear after reduction of their active centres by means of electrons trapped in water-ethylene glycol mixtures at the temperature of liquid nitrogen [1, 2]. In the reduced state, the active centre of the protein has an ESR signal with a g-factor of 1.94 [3, 4] which is convenient for our purposes.

Adrenodoxin↗
PubMed1976

Metalloprotein electron transfer reactions: analysis of reactivity of horse heart cytochrome c with inorganic complexes.

The reactions of horse heart cytochrome c with Fe(ethylenediaminetetraacetate)2-, Co(1,10-phenanthroline)3(3+), Ru(NH3)6(2+), and Fe(CN)6(3-) have been analyzed within the formalism of the Marcus theory of outer-sphere electron transfer, including compensation for electrostatic interactions. Calculated protein self-exchange rate constants based on crossreactions are found to vary over three orders of magnitude, decreasing according to Fe(CN)6(3-) greater than Ru(NH3)6(2+) greater than Fe(EDTA)2-. The reactivity order suggests that the mechanism of electron transfer involves attack by the small molecule reagents near the most nearly exposed region of the heme; this attack is affected by electrostatic interactions with the positively charged protein, by hydrophobic interactions that permit reagent penetration of the protein surface, and by the availability of pi symmetry ligand (or extended metal) orbitals that can overlap with the pi redox orbitals of the heme group.

Animals↗
PubMed1975

[Soluble cerebral metalloproteins. 1. Purification and properties of cerebral cortex cytochrome c].

Cytochrome c from grey matter of brain has been obtained as a homogeneous preparation by electrophoresis on polyacrylamide gel and following electrofocusing in ampholine solutions. Its molecular weight, content of iron, redox potential and isoelectric point have been established. The absolute spectra of its oxidized and reduced forms are presented. Cytochrome c of brain cortex is similar in its properties to that obtained from other animal tissues as the heart and adrenal cortex.

Animals↗
PubMed1976

[Soluble cerebral metalloproteins. II. Superoxide dismutases of cerebral gray and white matter].

Superoxide dismutases (SOD) of high purity have been obtained from grey and white matter of bovine brain cerebral hemispheres. The SOD obtained have been shown to have three isoenzymes (a, b, c). A study of the catalytic and macromolecular properties of the SOD obtained from grey and white matter of cerebral hemispheres as well as their optical and electron paramagnetic resonance spectra indicates that both proteins possess similar properties. The possible function of SOD in grey and white matter of brain is discussed.

Animals↗