JBC, Vol. 252, Issue 17, 5977-5980, Sep, 1977
Properties of soluble rat brain histone lysine methyltransferase
J. C. Wallwork, D. P. Quick and J. A. Duerre
Histone-lysine methyltransferase has been solubilized from rat brain
chromatin by repeated extraction with distilled water. The enzyme was
further purified by chromatography on DEAE-cellulose and gel filtration.
With chromosomal-bound histones as substrates, the enzyme methylated only
the lysyl residues in histones H3 and H4. The ratio of N epsilon-mono-: N
epsilon-di-: N epsilon-trimethyllysine in histone H3 was 1.8:1.0:0.45 and
the ratio of N epsilon-mono-: N epsilon-dimethyllysine in histone H4 was
0.7:1.0. The enzyme loses specificity with soluble histones as substrates;
however, histones H3 and H4 were still the best methyl acceptors. The pH
optima for the enzyme with soluble histones H3 and H4 as substrates were
8.2 to 8.7 and 7.2 to 8.0, respectively. S-Adenosyl-L-homocysteine, one of
the products of the reaction, was a competitive inhibitor with respect to
S-adenosyl-L-methionine.