Zinc-ligand interactions histidine

The 12 residues between the second cysteine zinc ligand and the first histidine ligand of the classic zinc finger motif form the "finger region". Structurally, this region comprises the second p strand, the N-terminal half of the helix and the two residues that form the turn between the p strand and the helix. This is the region of the polypeptide chain that forms the main interaction area with DNA and these interactions are both sequence specific. 

Hydrogen bond interactions are important for the function of histidine as a zinc ligand. For example, in a survey of zinc-binding motifs, Christianson and Alexander (1989, 1990) reported that head-on and... 

Excess copper is toxic to cells. On one hand, copper ions can avidly bind to biomolecules by ligand interaction with cysteines or by binding to histidine-rich regions. Copper ions could also be incorporated into proteins instead of zinc or other metal ions during biosynthesis. On the other hand, copper ions can form radicals by a Fenton-type reaction as shown in Eq. (1) ... 

The free a-amino group of the dipeptide interacts with glutamate at position 270 the y-COOH group is involved and a water molecule is located between the amino and carboxyl groups. Interactions which directly involve the catalytic action of the enzyme are as follows (a) the carbonyl of the peptide bond ligands to a zinc atom, which itself is further bound to two histidines (positions 69,196) and a glutamate... 

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