The provided reference discusses stereoisomers (specifically, L and D forms) rather than structural isomers. Therefore, the direct answer using the provided text is that no amino acids are structural isomers according to the provided reference. The reference indicates that all amino acids except glycine are stereoisomers, specifically L and D mirror images.
Here is why understanding the difference is important:
-
Structural Isomers: Also known as constitutional isomers, these are molecules that have the same molecular formula, but differ in the bonding arrangement or connectivity of atoms. Imagine rearranging the same LEGO blocks into different structures; the chemical formula stays the same, but the spatial layout differs.
-
Stereoisomers: These molecules have the same molecular formula and the same bonding connectivity, but they differ in the spatial arrangement of atoms in space. The most common example of this is the L- and D- forms of molecules, which are mirror images of each other like your left and right hands.
-
The provided reference highlights that most amino acids are found in the L-form.
-
Glycine does not exhibit stereoisomerism due to having two hydrogen atoms attached to the alpha carbon, which is its chiral center.
Because the provided reference specifically discusses stereoisomers and not structural isomers, there is no information that supports that any amino acids are structural isomers. Therefore, the answer is that no amino acids are structural isomers according to the reference.
