are these binding site are lewis base or lewis acid (10 marks) Two metal binding sites in proteins are shown below. In both cases, the metal cation has been remove from the spot indicated by the arrow. In a) the metal cation was interacting with the circled atoms, which are all xygens. In b), the metal cation is interacting with two sulfurs and two nitrogens Test #2a CHEM 2501 50 marks, 1.5 hours b) H20 HN Asp Met Asp His- Me Glu Main chain Cys Asp 0. Solution Metal ligand interactions is a classic example of lewis acid-base interactions. In binding with metals, the metals have empty orbitals which are capable of accepting electron pair from lewis base to form adduct or complexes. Thus the metal ion is inherently a lewis acid and the binding ligands act as lewis base. So to say, the binding sites are basic as in they will only accept a lewis acid. In the above examples, all the O, N and S bind to the metal ion by donating a lone pair. .

1. are these binding site are lewis base or lewis acid
(10 marks) Two metal binding sites in proteins are shown below. In both cases, the metal cation
has been remove from the spot indicated by the arrow. In a) the metal cation was interacting with
the circled atoms, which are all xygens. In b), the metal cation is interacting with two sulfurs and
two nitrogens Test #2a CHEM 2501 50 marks, 1.5 hours b) H20 HN Asp Met Asp His- Me Glu
Main chain Cys Asp 0.
Solution
Metal ligand interactions is a classic example of lewis acid-base interactions.
In binding with metals, the metals have empty orbitals which are capable of accepting electron
pair from lewis base to form adduct or complexes. Thus the metal ion is inherently a lewis acid
and the binding ligands act as lewis base.
So to say, the binding sites are basic as in they will only accept a lewis acid. In the above
examples, all the O, N and S bind to the metal ion by donating a lone pair.