Mitochondrial DNA polymerase, deoxyribonuclease and ribonuclease H activities from brain of chick embryo |
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Authors: | L Soriano J Smith Y Croisille and B Dastugue |
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Institution: | Institut d''Embryologie et Tératologie expérimentales du C.N.R.S., 49bis, Avenue de la Belle-Gabrielle, 94130 Nogent-sur-Marne, France |
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Abstract: | R-DNA polymerase, D-DNA polymerase, DNase and RNase H activities in mitochondria from chick embryonic brain were studied by ion-exchange chromatography. Two main fractions were separated according to their chromatographic behaviour: a fraction M Ib which is eluted with the washing buffer from two successive DEAE-cellulose columns and a fraction M IV which is eluted at 400 mM KC1 from a phosphocellulose column. Although the two fractions contain both the DNA polymerase and the degrading activities, all the specific activities are higher in fraction M IV than in fraction M Ib. Heat inactivation experiments have shown that R-DNA polymerase is inactivated in both fractions, whereas RNase H and DNase are not affected. Thus, degrading activities and R-DNA polymerase activity seem to be catalyzed by different molecular entities. However the fact that in most cases these activities co-chromatograph suggests that the corresponding molecules form rather stable complexes. |
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