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. Author manuscript; available in PMC: 2008 Dec 5.
Published in final edited form as: J Cell Biochem. 2008 Sep 1;105(1):108–120. doi: 10.1002/jcb.21803

FIGURE 5. Heparin inhibits HAT activity toward histone H3 and histone H4 substrates.

FIGURE 5

pCAF HAT Enzyme (0.5μg; 0.51 μM) and p300 HAT Domain (1.67μg; 0.33 μM) were assayed for HAT activity in the absence and presence of heparin using a commercially available HAT assay kit. In Panel A, heparin-mediated inhibition of pCAF HAT activity was assayed using histone H3 (open circles) and histone H4 (filled circles) peptide substrates. In Panel B, heparin-mediated p300 HAT activity was assayed using histone H3 (open squares) and histone H4 (filled squares) substrates. In both panels, the data are expressed as relative absorbance ± SD. The average background absorbance in the absence of enzyme was 0.151, which was subtracted from all absorbance values from enzyme containing samples. The activity of pCAF with H3 and H4 peptides was measured three times; the activity of p300 with the H3 and H4 peptides was measured twice.