What

is the only amino acid with a substituted alpha amino group? the

presence of this amino acid influences protein folding byforcing a

bend in the chain - draw its structure.

Proline

Explanation:

Proline's unique characteristic it's that it is the only amino acid where the side chain is connected to the backbone twice forming a nitrogen-containing ring, this means it has a substituted alpha-amino group. This characteristic is important to the structure of proteins, because, contrary to glycin which adopts many main chain conformations, proline if most commonly found in tight turns because of its rigidity.

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