Calf thymus ribonuclease H IIa activity lacks ribonuclease H specificity.
Less purified fractions of ribonuclease H IIa activity of calf thymus display divalent cation-dependent ribonuclease H activity and divalent cation-independent ribonuclease activity. Because the ratio of the two enzyme activities does not change during successive chromatographic procedures, we suggest that ribonuclease H IIa activity is indeed able to degrade both ssRNA and the RNA moiety of RNA.DNA-hybrids. Ribonuclease H IIa activity can therefore be differentiated from calf thymus ribonuclease H I and H IIb by its lack of ribonuclease H specificity. The native molecular mass of ribonuclease H IIa activity is between 23 and 28 kDa. Under denaturing conditions a 23 kDa-protein band copurifies with the enzyme activity suggesting that this enzyme is monomeric.
Lehrstuhl für Allgemeine Genetik, Universität Tübingen, Federal Republic of Germany.
H
H
Vonwirth
P
P
Frank
W
W
Büsen
D000818:Animals; D002417:Cattle; D004591:Electrophoresis, Polyacrylamide Gel; D004722:Endoribonucleases / Q000302:isolation & purification / Q000378:metabolism*; D008970:Molecular Weight; D011489:Protein Denaturation; D012313:RNA / Q000378:metabolism; D016914:Ribonuclease H; D012259:Ribonuclease, Pancreatic / Q000378:metabolism; D013379:Substrate Specificity; D013950:Thymus Gland / Q000201:enzymology*
D012313:RNA; D004722:Endoribonucleases; D016914:Ribonuclease H; D012259:Ribonuclease, Pancreatic