Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A calcium-dependent endoribonuclease isolated from Trypanosoma brucei cytoplasm has been further characterized. The products of exhaustive endonuclease digestion of poly(A), which the enzyme cleaved preferentially, were small oligonucleotides terminated by a 5'-phosphoryl group. Its apparent Km value was 0.8 mM using poly (A), and 3.3 mM using transfer RNA. The base specificity of the endoribonuclease was further verified by using synthetic heteropolyribonucleotides as substrates. The enzymatic reaction was inhibited by polyamines, polyanions, iodoacetic acid and the heavy metals, but only very slightly by N-ethylmaleimide and iodoacetamide. A possible implication of the enzyme in the turnover of messenger RNA is discussed.
 ...
PMID:Studies on the catalytic properties of the calcium-dependent endoribonuclease of Trypanosoma brucei cytoplasm. 617 71

Our objective was to identify the endonuclease responsible for DNA degradation in the ovary and determine its localization relative to the developmental state of ovarian follicles. Immature rats were treated with diethylstilbestrol (DES; DES group), DES + eCG (eCG group) or DES + eCG + hCG (hCG group). Nuclei of the eCG and hCG but not the DES group contained a 32/34-kDA DNase I-like endonuclease activity that was Ca2+/Mg(2+)-dependent, stimulated by Mn2+, optimal at pH 7, and identified by anti-DNase I antibody. G-actin, Zn2+, dithiothreitol, aurintricarboxylic acid, and sodium aurothiomalate, but not iodoacetic acid, inhibited the activity. Addition of eCG nuclear protein extracts to nuclei from the DES group induced oligonucleosomal DNA fragmentation, which could be prevented by pretreatment of the extracts with anti-DNase I antibody. DNase I was immunolocalized in nuclei of healthy luteal cells, antral follicle granulosa cells, oocytes of preantral follicles, atretic preantral follicles, and testicular spermatogonia, but was not observed in granulosa cells of preantral follicles, theca cells, antral follicle oocytes, or testicular spermatocytes. Nuclear extracts of rat kidney, liver, and spleen, and bovine, chicken, and human ovaries displayed DNase I-like activity. These results suggest that an endonuclease indistinguishable from DNase I is responsible for ovarian apoptotic DNA degradation.
 ...
PMID:Identification and localization of deoxyribonuclease I in the rat ovary. 931 85

Ca2+,Mg2+- and Ca2+,Mn2+-dependent and acid DNases were isolated from spermatozoa of the sea urchin Strongylocentrotus intermedius. The enzymes have been purified by successive chromatography on DEAE-cellulose, phenyl-Sepharose, Source 15Q, and by gel filtration, and the principal physicochemical and enzymatic properties of the purified enzymes were determined. Ca2+,Mg2+-dependent DNase (Ca,Mg-DNase) is a nuclear protein with molecular mass of 63 kD as the native form and its activity optimum is at pH 7.5. The enzyme activity in the presence of bivalent metal ions decreases in the series (Ca2+ + Mg2+) > Mn2+ = (Ca2+ + Mn2+) > (Mg2+ + EGTA) > Ca2+. Ca,Mg-DNase retains its maximal activity in sea water and is not inhibited by G-actin and N-ethylmaleimide, whereas Zn(2+) inhibits the enzyme. The endogenous Ca,Mg-DNase is responsible for the internucleosomal cleavage of chromosomal DNA of spermatozoa. Ca2+,Mn2+-dependent DNase (Ca,Mn-DNase) has molecular mass of 25 kD as the native form and the activity optimum at pH 8.5. The enzyme activity in the presence of bivalent metal ions decreases in the series (Ca2+ + Mn2+) > (Ca2+ + Mg2+) > Mn2+ > (Mg2+ + EGTA). In seawater the enzyme is inactive. Zinc ions inhibit Ca,Mn-DNase. Acid DNase of spermatozoa (A-DNase) is not a nuclear protein, it has molecular mass of 37 kD as a native form and the activity optimum at pH 5.5, it is not activated by bivalent metal ions, and it is inhibited by N-ethylmaleimide and iodoacetic acid. Mechanisms of the endonuclease cleavage of double-stranded DNA have been established for the three enzymes. The possible involvement of DNases from sea urchin spermatozoa in programmed cell death is discussed.
 ...
PMID:Purification and characteristics of Ca2+,Mg2+- and Ca2+,Mn2+-dependent and acid DNases from spermatozoa of the sea urchin Strongylocentrotus intermedius. 1288 41