Abstract: On the surface of the nucleosome, there are many regions for interaction with chromatin proteins, but an acidic patch, a negatively charged region formed by the residues of the histone H2A/H2B dimer, is especially prominent. The acidic patch is a target for anticancer drugs and an interaction locus for various pathogens. For instance, it was shown that this region is the binding site of the LANA protein of human gammaherpesvirus 8 and tethers the virus episomes to mitotic chromosomes. The development of methods for analyzing the binding of various compounds to nucleosomes is necessary both for understanding the mechanisms of chromatin regulation and for therapeutic agents' design. In this work, we propose a technique and measure the binding constant of the LANA protein fragment to the nucleosome. In contrast to previous studies, the measurements were carried out at a physiological salt concentration in the buffer solution. The proposed technique is based on the signal detection from the fluorescently labeled peptides after the separation of complexes of nucleosomes with peptides by gel electrophoresis. The paper also discusses mathematical models for analyzing the interaction between peptides and nucleosome and possible factors that can affect it.