[Cell nuclear DNases: multiplicity and heterogeneity].
In order to determine the ratio of activities of major endonucleases of rat liver chromatin, a stepwise fractionation of cell nuclear extracts by chromatography on phosphocellulose and gel filtration through Toyopearl HW60 was carried out. This procedure resulted in partially purified preparations of Ca2+,Mg2+-dependent endonuclease (55 +/- 10 kD), Ca2+,Mg2+-dependent endonuclease (30 +/- 10 kD), Mn2+-dependent endonuclease (30 +/- 5 kD) and acid cation-independent endonuclease. The Ca2+,Mg2+-dependent endonuclease with Mr of 55 +/- 10 kD made up to 57% of the nuclear extract activity in the presence of Ca2+ + Mg2+ and revealed a high calcium-magnesium synergism. Under the same experimental conditions, the 30 +/- 10 kD enzyme made up to 33% of the nuclear extract activity and revealed a low synergism. The activity of Mn2+-dependent endonuclease made up to 26% of the total nuclear extract activity in the presence of Mn2+, that of acid endonuclease--11% of the extract activity in 1 mM EDTA at pH 5.0. It was assumed that the low molecular weight Ca2+,Mg2+-dependent endonuclease represents a product of limited proteolysis of high molecular weight Ca2+,Mg2+-dependent endonuclease.
Basnak'ian
A G
AG
Bubnov
N V
NV
Votrin
I I
II
D000818:Animals; D002412:Cations; D002467:Cell Nucleus / Q000201:enzymology*; D003851:Deoxyribonucleases / Q000032:analysis*; D004720:Endonucleases / Q000378:metabolism; D008099:Liver / Q000201:enzymology; D051381:Rats
D002412:Cations; D003851:Deoxyribonucleases; D004720:Endonucleases
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