Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.22.1 (DNase II)
 429 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of ionic strength of the reaction medium on the pH optimum, specificity, and mechanism of action of the acid DNase isolated from mature eggs of the sea urchin Strongylocentrotus intermedius was studied. Changes in ionic strength of the reaction medium caused a displacement of the pH optimum of the enzyme to acidity or alkalinity. The region and range of this displacement depended on the buffer used and on the substrate structure. For single-stranded, duplex, and supercoiled forms of DNA, the pH optimum displacements were 1.0, 1.4, and 2.0 pH units, respectively. The pH optimum displacement changed the mechanism of action of the enzyme. Under optimum pH conditions, the enzyme cleaved supercoiled DNA only by the double-hit mechanism, and fragments of duplex DNA resulted due to the coincidence of breaks in opposite chains. On pH displacement to acidity, the enzyme acted by the mixed mechanism (single- and double-hit). And the quantitative ratio of products of the enzymatic hydrolysis of supercoiled DNA was significantly changed depending on the pH displacement to acidity or to alkalinity. The findings are explained by the effect of salt-dependent electrostatic interactions during the formation of a nonspecific DNA-enzyme complex.
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PMID:Effect of ionic strength on the pH optimum, specificity, and mechanism of action of acid DNase from mature eggs of the sea urchin Strongylocentrotus intermedius. 1100 89

The activation of DNase I by Mg, Mn, Co, Ni, Fe, Cd, Zn, Ba, Sr, Ca, and Cu ions has been studied by several methods, at different pH and salt concentrations. Mg, Mn, and Co are the best activators for initial stages of degradation. A synergistic effect is shown only by the pair Mg-Ca. Optimal pH of action is always situated at 6.5. DNase II is activated to about the same degree by alkaline earths and Mn ions. Cd and Cu are strong inhibitors. Optimal pH is always 4.6. By titration of liberated secondary phosphate groups, two stages in the hydrolysis of DNA by DNase I are evidenced: a rapid phase activated most by Mg and a slow phase activated by Ca. Some possible mechanisms of action of both enzymes are outlined and the general influence of metal ions is discussed.
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PMID:Activation of deoxyribonucleases by divalent cations. 1388 71

The level of the acid DNase activity in the hemocytes and digestive gland of the mussel Mytilus galloprovincialis after exposure to model marine pollutants, a detergent, gasoline and a copper salt, as well as to unknown environmental mixture at selected sampling sites, was investigated. The specific enzyme activity in unexposed mussels from mariculture area was higher in hemocytes than in digestive gland. Concentration and time effect patterns of DNase activity revealed tissue- and pollutant-specific responses to model marine pollutants. Since in some cases the pollutant effect could not be detected by measurement of acid DNase in single tissue only, digestive gland/hemocyte (Hep/Hem) ratio was introduced. The Hep/Hem ratio enabled the detection of pollutant effect at the significance level. Field investigations indicated that the digestive gland is a suitable tissue for discrimination of polluted areas from maricultured area. Additionally, the Hep/Hem ratio enabled differentiation within a group of polluted sampling sites that differ in the type of pollutants and/or environmental conditions.
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PMID:Effect of marine pollutants on the acid DNase activity in the hemocytes and digestive gland of the mussel Mytilus galloprovincialis. 1827 21


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