The protein amino acids are generally in the __________ configuration.

### Why this is right The standard amino acids incorporated into proteins are generally L amino acids. Glycine is a special case because it is achiral and therefore is not assigned an L or D configuration. ### The concept L and D describe configurations relative to a reference molecule, not the direction in which a compound rotates light. Confusing configuration with optical rotation can lead to incorrect conclusions about a molecule’s behavior. ### Terms - **Configuration**: the fixed three-dimensional arrangement of atoms around a stereogenic center. - **Achiral**: lacking a chiral center and not having a non-superimposable mirror image. ### Remember Protein amino acids are generally L, with achiral glycine as the exception.