MOLECULAR SIZE OF IN VIVO LIVER CATALASE-DEPRESSING SUBSTANCE FROM RHODAMINE SARCOMA OF RAT

Abstract

The in vivo liver catalase-depressing substance present in the water-soluble extract from Rhodamine sarcoma of rats was found to have various molecular weights.
1) The extract contains a proteolytic enzyme.
2) By molecular sieve of the extract on Sephadex G-200, the catalase-depressing substance is separated into four fractions according to their molecular weight; F-1 of >200, 000, F-2 of 200, 000-40, 000, F-3 of 40, 000-7, 000, and F-4 of <7, 000. All the fractions other than F-4 show both the catalase-depressing and proteolytic activities.
3) When the extract is heated at pH 4 and 70° for 15min, the proteolytic activity is mostly lost, whereas the depressing activity is not affected. F-1, F-2, and F-3 obtained from the heated extract show the depressing activity. By repeated heating of F-1 and F-2, the substances present are further segmented into constituents corresponding to F-2, F-3, and F-4. All the resulting F-3's do not change in molecular weight on repeated heating. These F-3's migrate, in polyacrylamide gel electrophoresis, forming a single zone of protein. The molecular weight of F-3's is composed of 80% protein and 20% DNA.
4) The elemental unit of the catalase-depressing substance seems to have a molecular weight of approximately 12, 000, and its protein moiety is indispensable for the depressing activity. The depressing activity may be exhibited by various complexes different in molecular weight, which are formed beteween the elemental unit and others.