The NH group of Gly184 is in position to form a hydrogen bond with N3 of the substrate.

Reaction with the NH group in an amine.

It is related to the more common dye indigo by replacement of two NH groups with sulfur atoms.

Thioindigo, where the two NH groups are replaced by S atoms, is deep red.

Next, a second NH group is transferred from a glutamine to the first carbon of the glycine unit.

Because this region has free NH groups, it will interact with negatively charged groups such as phosphates.

The -NH group of the indole ring is not important for binding and activation.

The main chain NH groups bind the anions while the side chain atoms are often not involved.

Proline residues lack NH groups so are rare in nests.

This has four NH groups instead of three.