title: DNA-bound proteases. Partial characterization of proteolytic activities in commercial sources of DNA.
abstract: The presence of variable amounts of protease in commercial sources of calf thymus DNA has been established by means of three independent methods; electrophoresis, substrate labelling and microfluorometry. The microfluorometric method, which is particularly useful for initial velocity measurements, has been used to characterize this proteolytic activity, either bound to DNA or solubilized by salt extraction. The proteolytic activity had a maximum at neutral pH and was not affected by NaCl concentration up to 0.5 M. Studies of specificity with natural substrates showed a higher V for protamine and lower Km for histones. The proteolytic activity was resolved by gel filtration chromatography in two major molecular weight species, differing in thermal stability and pH activity profile.
mesh_terms: D000818:Animals; D002417:Cattle; D004247:DNA / Q000302:isolation & purification*; D006657:Histones; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010447:Peptide Hydrolases / Q000302:isolation & purification*; D011479:Protamines; D013050:Spectrometry, Fluorescence; D013379:Substrate Specificity; D013950:Thymus Gland / Q000201:enzymology
chemical_list: D006657:Histones; D011479:Protamines; D004247:DNA; D010447:Peptide Hydrolases