Alanine is an amino acid; these are the building blocks of proteins. All amino acids have an identical basic structure, but have individual portions stuck onto this basic structure. In the case of alanine, this portion is one of the simplest of all amino acids, with only one carbon and three hydrogen atoms. The exact appearance of the structure of alanine can vary according to whether the alanine occurs in nature, or is synthetically produced.
In its entirety, alanine contains 13 different atoms. This includes seven hydrogens, three carbons and two oxygens, along with one nitrogen. Most of the structure of alanine is made up of a basic collection of atoms which is common to all amino acids. 20 amino acids are found in nature, and each of these only vary in one portion of their structure, which is known as the R-group.
Amino acid basic structure revolves around one carbon atom in the center of the molecule. Onto this is stuck three different parts, which are called the amino group, the carboxylic acid group and a lone hydrogen. An amino group contains three hydrogen atoms and one nitrogen atom, whereas the carboxylic acid group includes one carbon and two oxygens. The lone hydrogen is next to the central carbon; the other two groups are located along a horizontal plane, with the carbon and hydrogen in the middle.
Where the structure of alanine differs from other amino acids is the R-group. Composed of one carbon and three hydrogens, this R-group is quite simple compared to the majority of other amino acids. Due to this structure, alanine is a neutral molecule, with no strong negative or positive electrical interaction with other molecules. The R-group is located perpendicularly to the horizontal plane of the other components.
Chirality is an important concept in dealing with amino acid structure. This concept can be described as two chemically identical molecules being mirror images of each other. With regard to the structure of alanine, the mirror image can occur when the groups stuck onto the central carbon are swapped to the other side of the carbon. Human hands, with identical components, but obvious differences in structure, can illustrate this. Each mirror image is known as the L-isomer or the R-isomer, like a left hand or a right hand.
Only the L-isomer of alanine occurs in nature, but when humans synthetically make alanine, the R-isomer can also occur. Alanine molecules with a right-handedness are not useful in creating proteins in animals, though, as the cell machinery only recognizes the L-isomer. Scientific techniques can identify the presence of L- or R-isomers in a sample by the way in which they direct light rays shone on them.