Question

Common ions in enzyme systems are those that have low site preference energies (from Ligand Field Stabilization Energy; LFSE) such as Zn(II), and Mn(II) rather than Ni(II) or Cu(II). Discuss this phenomenon in terms of the entatic state hypothesis.

Answer 1

Entactic state hypothesis states that a state of an atom or group has it's geometric and electronic condition adapted for function in protein. So, in the process of protien functioning the metal has to adopt various geometry. Hence, if a metal doesn't have or have low site preference energy (LHSE) such as Zn(ii) and Mn(ii), it will be easy for the metal ion to adopt different geometry without much loss of energy. Whereas if a metal ion has higher LFSE, changing of geometry will be achieved by loss of much energy which will be not favourable.