Conformational Analysis of Proteins Ramachandrans Method

Ramachandran pointed out that the folding of a protein depends on the conformation adopted by the two central cr-bonds of each amino acid and that this conformation can be described by using the dihedral angles I and 

In contrast with the right-handed a-helical structure of proteins a similar left-handed folding is theoretically possible in which the dihedral angles would be approximately VF = 50° and I = 90°. Because of the substituent 

Only the achiral glycine can readily adopt conformations different from those in the favored regions proline, because of, the ring system, is highly constrained in its conformation. 

Metals in Proteins - Tools for the Stabilization of Secondary Structures and as Parts of Reaction Centers 

Very often metal ions are found encapsulated in the interior of a protein (or located on its surface). These metal ions can undergo two different functions  

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