Amino Acid Three Letter Codes: Study with Video Lessons, Practice Problems & Examples

Amino acids can be abbreviated using a three-letter code and a one-letter code for efficiency. Most three-letter codes consist of the first three letters of the amino acid's name, except for asparagine (ASN), glutamine (GLN), tryptophan (TRP), and isoleucine (ILE), which have phonetic variations. A mnemonic to remember these is "asparagine chilling on 3 tropical islands." Understanding these codes is essential for discussing protein structure and function, as they facilitate quick reference to amino acids in biochemical contexts.

Amino Acid Three Letter Codes Concept 1

Now amino acids can be long and take a while to write out. For convenience, we're going to say amino acids can be abbreviated in 2 different ways. We have what's called a three-letter code and what's called a one-letter code for these amino acids. Now abbreviations are commonly used and were designed to be easily memorized. So as we discuss the different types of amino acids, we'll talk about the three-letter codes that we can use for them, as well as the one-letter code that we can use for them. This will help us to write out amino acids much more quickly and efficiently when discussing their interactions with one another and overall when we come to the idea of a fully functional protein.

Amino Acid Three Letter Codes Concept 2

Now when it comes to the three-letter code for amino acids, we're going to say most three-letter abbreviations are simply the first three letters of the amino acid. And when we say most amino acids, we're talking about 16 out of the 20. That leaves us 4 that don't follow this rule. We're going to say 4 of the 3-letter abbreviations are slightly altered to help identify them phonetically. And that means by sound of speech. And they are asparagine, which is ASN, Glutamine which is GLN, Tryptophan which is TRP, and isoleucine which is ILE. Now, a way to help us remember this is that we have the phonetic three-letter code, and our memory tool here is that asparagine is chilling on 3 tropical islands. So here we have an image of 3 islands, and on each one, asparagine has a chance of just chilling. So here, we have asparagine as asparagus, and I'm chilling on 3 tropical islands. So asparagine, ASN, chilling, GLN on 3 because this is 3 letter code, tropical, and we use tryptophan, islands. So just keep that in mind when you have to remember the 4 amino acids that don't simply use the first three letters of their names for the three-letter code. Now if we come down here, we're going to say amino acid, 3-letter symbols. As we can see, we have the first three letters represent the 3-letter code for a majority of these amino acids, except for the 4 that we've highlighted. So again, remember, asparagine is ASN, then we have glutamine, which is GLN, isoleucine is ILE, and then tryptophan is TRP. So just remember, asparagine chilling on 3 tropical islands. That helps you remember those amino acids are a bit different from the other 16. They don't follow the first three letters of their name when it comes to the three-letter code.

Amino Acid Three Letter Codes Example 1

Match the amino acids to their appropriate three-letter codes. Remember, four of our amino acids don't follow the common trend of using the first three letters of their name. The way we remember this is by imagining asparagine chilling on three tropical islands. These islands represent the four amino acids that don't follow the first three letters in terms of their three-letter code. In this method, asparagine would be identified with the code ASN. Glutamine is GLN. Isoleucine, which is another exception, uses the code ILE. Tryptophan is abbreviated as TRP, not TRIP.

The remaining amino acids follow the first three letters of their name to form their three-letter codes. For example, glutamate would be GLU, and leucine would be LEU. This is how we match each of the amino acids to their appropriate three-letter codes.

Convert the following amino acids into their 3-letter codes: Glycine, Isoleucine, Valine, Tryptophan, Proline.

• A. Gly, Ile, Val, Try, Pro
• B. Gly, Iso, Val, Trp, Pro
• C. Gly, Ile, Val, Trp, Pro

Here’s what students ask on this topic:

What are the three-letter codes for all 20 amino acids?

The three-letter codes for the 20 amino acids are as follows: Alanine (Ala), Arginine (Arg), Asparagine (Asn), Aspartic acid (Asp), Cysteine (Cys), Glutamine (Gln), Glutamic acid (Glu), Glycine (Gly), Histidine (His), Isoleucine (Ile), Leucine (Leu), Lysine (Lys), Methionine (Met), Phenylalanine (Phe), Proline (Pro), Serine (Ser), Threonine (Thr), Tryptophan (Trp), Tyrosine (Tyr), and Valine (Val). Note that Asparagine, Glutamine, Tryptophan, and Isoleucine have phonetic variations in their three-letter codes.

Why do some amino acids have phonetic variations in their three-letter codes?

Some amino acids have phonetic variations in their three-letter codes to avoid confusion and ensure clarity in communication. For example, Asparagine (Asn), Glutamine (Gln), Tryptophan (Trp), and Isoleucine (Ile) do not follow the first three letters of their names. These variations help distinguish them from other amino acids with similar names or abbreviations. The mnemonic 'asparagine chilling on 3 tropical islands' can help remember these exceptions.

How can I easily memorize the three-letter codes for amino acids?

To easily memorize the three-letter codes for amino acids, you can use mnemonics and associations. For example, the mnemonic 'asparagine chilling on 3 tropical islands' helps remember the exceptions: Asparagine (Asn), Glutamine (Gln), Tryptophan (Trp), and Isoleucine (Ile). For the other amino acids, most three-letter codes are simply the first three letters of their names, making them easier to recall.

What is the importance of knowing amino acid three-letter codes in biochemistry?

Knowing amino acid three-letter codes is crucial in biochemistry because it allows for efficient communication and documentation of protein sequences and structures. These codes facilitate quick reference and understanding of amino acid interactions, which is essential for studying protein function, enzyme activity, and biochemical pathways. They also help in writing and interpreting scientific literature and research data more effectively.

What mnemonic can help remember the exceptions to the three-letter code rule for amino acids?

The mnemonic 'asparagine chilling on 3 tropical islands' can help remember the exceptions to the three-letter code rule for amino acids. This mnemonic represents the four amino acids with phonetic variations in their three-letter codes: Asparagine (Asn), Glutamine (Gln), Tryptophan (Trp), and Isoleucine (Ile). Visualizing asparagine as asparagus chilling on three tropical islands can make it easier to recall these exceptions.