Histone Acetyltransferase in Chromatin. Extraction of Transferase Activity From Chromatin

Document Type

Article

Publication Date

1-1-1972

Description

Previous work has attempted to localize nuclear histone acetyltransferase activity in the cromatin. Evidence was presented indicating that the transfer of 14C-acetate from 14C-acetyl CoA to histones in chromatin was an enzymatic process. We now report on the extraction of part of the histone acetyltransferase activity from rat liver chromatin, employing a procedure originally described for extraction of DNA-dependent RNA polymerase. The Km of the extracted transferase activity for the substrate acetyl CoA was 5 × 10-7, the Q10: 1.8 and the optimal pH: 7.1. Serum albumine, protamine and polylysine were poor substrates as compared to histones. Activity of extracted or heated chromatin was not restored upon incubation in the presence of extract. Also the selectivity exhibited by the transferase activity in unextracted chromatin towards arginine-rich histones, was much less pronounced in the extracts prepared from it. It is possible that the influence of steric factors contributing to this specificity in native chromatin is lost upon isolation of the enzyme from it. Alternatively, a less specific isoenzyme may have been extracted.

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