Amino Acid Three Letter Code: Videos & Practice Problems

Amino acids, the building blocks of proteins, can be abbreviated in two primary ways: using three-letter codes and one-letter codes. Each of the 20 standard amino acids has its own unique three-letter abbreviation, with a total of 40 abbreviations when combined with the one-letter codes. Memorizing these abbreviations is essential, as they are widely used in the scientific community, particularly among biochemists.

Most three-letter codes are derived from the first three letters of the amino acid's name, making them relatively easy to remember. However, four amino acids have slightly altered three-letter codes that are designed to be phonetically recognizable. These amino acids are asparagine (Asn), glutamine (Gln), tryptophan (Trp), and isoleucine (Ile). The unique codes for these amino acids help distinguish them based on their pronunciation rather than their spelling.

To aid in memorization, a mnemonic can be helpful: "a spare gene chilling on 3 tropical islands." This phrase not only highlights the phonetic nature of the three-letter codes for asparagine, glutamine, isoleucine, and tryptophan but also connects asparagine to its origin, as it was first isolated from asparagus. The mnemonic emphasizes the number three, representing the three amino acids that require special attention.

In summary, while 16 of the amino acids have straightforward three-letter codes that are simply the first three letters of their names, focusing on the four phonetic codes will streamline the memorization process. By mastering these key abbreviations, students can enhance their understanding of protein structure and function, which is fundamental in biochemistry.

For reference, here is a chart of all 20 amino acids organized alphabetically with their corresponding three-letter codes: