Glutamine / GLN / Q (EnzDes coloring)
Glutamine (GLN or Q) is a hydrophilic amino acid. Its shape in Foldit is almost the same as glutamate (glutamic acid), to which it is closely related. The CPK or EnzDes coloring options (found in view options) can be used to tell the two apart.
In the Foldit Lua interface, the functions structure.GetAminoAcid and structure.SetAminoAcid use lowercase "q" for glutamine.
Glutamine's sidechain can act as both a hydrogen bond donor and acceptor.
Glutamine's sidechain contains an oxygen atom which can act as a hydrogen bond acceptor, and a nitrogen atom which can act as a hydrogen bond donor. See the Sidechain Bonding Gallery and the Sidechain Bonding Table for other sidechain donors and acceptors.
For more, see Glutamine on wikipedia.