An ATPase depending on the presence of single-stranded DNA from mouse myeloma.

An ATPase was purified from mouse myeloma MOPC 70E the activity of which depends on the presence of single-stranded DNA and divalent cations such as Mg2+, Mn2+, Ca2+, Ni2+ or Fe2+. The enzyme splits both ribonucleoside and deoxyribonucleoside triphosphates but preferentially ATP and dATP yielding nucleoside diphosphates and inorganic phosphate. The enzyme has an absolute requirement for single-stranded DNA. Alternating double-stranded polydeoxynucleotides are only slight effective, and native double-stranded DNA, single-stranded and double-stranded RNAs as well as DNA - RNA hybrids are ineffective in stimulating the ATPase. The enzyme has further characterized by sedimentation in a sucrose density gradient (s20, w = 5.5 S) and by isoelectric focussing in an ampholine pH gradient (pI = 6.5).