Classical zinc fingers, also known as ββα, are highly conserved domain. Even though their secondary structure is similar, they physiochemical properties are different. For example the length of the linker between binding cysteine residues has a significant impact on their stability. Competition studies with metal chelators (EGTA, HEDTA, EDTA, TPEN) are used to precisely determine Kd values of divergent ZF sequences. Zn(II) ion is necessary to proper functioning of zinc finger domain, thus; it is important to maintain its cellular homeostasis.