Alanine. Computer graphic of a molecule of the amino acid alanine. The molecular formula is C3.H7.NO2. Here, atoms are represented as spheres and colour-coded: carbon (green), oxygen (pink), nitrogen (blue), hydrogen (white). Lines represent atomic bonds and they also show the skeleton of the molecule. Alanine occurs in L- and D- forms (left- and right-handed forms). It is one of the twenty most common natural amino acids, and is extremely important in that it is a component of nearly all proteins.