Alanine has two
isomers. They are exactly the same except they are backwards from each other. This sort of isomer is called an
optical isomer An isomer in chemistry is a chemical compound that has the same molecular formula as another, but it has a different arrangement of atoms in space. In other words, isomers are compounds with the same molecular formula but different structural formula. Different isomers have different chemical properties (that is, they may look, or smell, or taste different from each other).