Ni-NTA purification, problem with the chaperone protein
If chaperone proteins are not an expected binding partner to your protein/peptide fragment then you need to use imidazole in your lysis and wash buffer ranging from 1 to 10 mM depending on how stringent you want but 1 mM worked for me. Can go higher than 10 mM if the problem does not resolve but don't go too high since imidazole is also used to get the purified proteins off the nickel beads as an elution buffer!