Protein catabolism in thymus nuclei

Comparison of the proteins of condensed and extended chromatin fractions of rabbit liver and calf thymus

“…Evidence against a Chromatin Protease Artifact. Many chromatins are known to contain protease activity (Furlan and Jericijo, 1967;Stellwagen et al, 1968;Panyim et al, 1968;Bartley and Chalkley, 1970;Kurecki et al, 1971;Garrels et al, 1972). The optimal conditions for the activity of this protease are similar to those existing at the end of the elution of chromatin from the Ectham-cellulose column.…”

Stabilization of histones from rat liver

“…Not only is this activity present in histones prepared without acid extraction (e.g., adsorption onto BioRex 70), but it has even been noted in HCl extracts of chromatin [2].…”

“…The protease which degrade the histones present a serious obstacle to many types of studies on the histones themselves and also studies of their interaction with nor&stones and DNA as in reconstitution. Not only is this activity present in histones prepared without acid extraction (e.g., adsorption onto BioRex 70), but it has even been noted in HCl extracts of chromatin [2].…”

Partial fractionation and chemical characterization of the major nonhistone chromosomal proteins

“…No work has yet been done-no assay is as yet available-to explore the possible structural role of NHC proteins. Several enzyme activities are known to be associated with the isolated chromatin, e.g., histone protease (Furlan and Jericijo, 1967;Garrels et al, 1972) and histone acetyltransferase (Gallwitz, 1971); see Elgin et al (1971) for a more detailed discussion of this aspect. It should be noted that if present estimates of amounts of several important enzymes (including RNA polymerase) are correct, they are present in chromatin at levels too low to be observed by the techniques used here (significantly less than 1 % of the NHC protein) (S. C. Froehner, personal communication 1971).…”