Abstract:
A non-pyrimidine dimer ultraviolet-damage specific endonuclease has been identified from extracts of Micrococcus luteus and highly purified by a combination of gel filtration and affinity chromatography. The enzyme is catalytically homogenous judging from interference in incision assays. The enzyme has a broad pH optimum at 7.3 to 7.9 and requires 07 mM Mg 2+ or 35mM NaC1 for normal levels of activity. There is no obligatory cofactor requirement. The incision activity of the enzyme as a function of photochemical damage is 63% at 390 J/m 2. There is no activity of the enzyme on native or thermally denatured DNA. The endonuclease acts with almost equal facility on heavily ultraviolet damaged DNA, gamma irradiated DNA, osmium tetroxide treated DNA and acid depurinated DNA substrates. The enzyme has an approximate sedimentation coefficient of 2. 15, Stokes radius of 17A° and molecular weight of 17000 1000 daltons.
Page(s):
193-209
DOI:
DOI not available
Published:
Journal: Pakistan Journal of Zoology, Volume: 19, Issue: 2, Year: 1987