Abstract: With a view to finding out precisely how small peptides recognize a particular binding site of DNA, we have accomplished DNA binding studies of two peptides, H-Tyr-Arg-OH (YR) and H-Gly-Gly-His-OH (GGH) by using measurements in comparison with the binding between DNA and Hoechst 33258. The inhibition mode by YR and GGH to DNA binding of Hoechst 33258 was analyzed by Lineweaver-Burk plot which shows the plot of typical competitive inhibition at concentration of Hoechst 33258 from 3.66 (10^-9 mol/L to 1.09 ( 10^-8 mol/L. And it is concluded that YR binds to DNA in its minor groove (AT rich regions) with a binding constant K = 1.02 ( 108 (mol/L)^-1. The GGH (s specificity is reduced at high concentration because it can also bind GC base pair.

Key words: DNA, Peptide, Competitive inhibitor, Site specific binding