Initial velocity and product inhibition kinetics of the histone acetyltransferase (EC 18.104.22.168) reaction indicate that the rat liver nuclear enzyme operates under a rapid equilibrium ordered bireactant mechanism. Histone adds first to the enzyme, and under the conditions of the experiment Ka = 0 as acetyl coenzyme A (CoA) concentration approaches saturating conditions. The Km for acetyl-CoA was 2.10 ± 0.48 μM. Inhibition with acetyllysine resulted in a Kiq for the enzyme-acetyllysine complex of 1.96 ± 0.30 mM. Inhibition with CoA yielded Kip for the ternary complex of 3.19 ± 0.48 μM. These results indicate that the enzyme activity is comparatively independent of histone concentration, and, since the enzyme is sensitive only to acetyl-CoA and CoA concentrations, the enzyme will tend to maintain histones in the acetylated state.
|Original language||English (US)|
|Number of pages||4|
|State||Published - 1981|
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