Nomenclature

The most generally accepted and used names for amino acids are those common names that are shown on the Common Names of Amino Acids page in this section. There is also list of these names and structural formulas in your textbook (and in your workbook in Lesson 8).

IUPAC Names

The IUPAC method for naming these amino acids is fairly simple, yet it has not found extensive use. I don't see much point in having you memorize twenty common names for individual compounds for this lesson (although that would be useful in Lesson 8). Therefore, you won't be held responsible for the common names for amino acids. However, you have already learned the IUPAC method for naming other types of organic compounds, and it is very easy to apply that to amino acids. So I will expect you to be able to do that for the simpler amino acids.

Example

Let's go through one example from structure to name, then you can practice going from name to structure.

In this amino acid we have a carboxylic acid with five-carbon chain and with an amino group on the second carbon atom and a methyl group on the third carbon atom. Thus, the IUPAC name for this compound is 2-amino-3-methylpentanoic acid.

str5ile.jpg (5036 bytes)

Practice

Now, try your hand working with the IUPAC names by matching the IUPAC names listed below (also shown in Exercise 12 in your workbook) with the common names and structures of amino acids shown on the Common Names of Amino Acids page (also found in your textbook, in Lesson 8 in your workbook and in the lab).

Use these IUPAC names to draw the structural formulas for the amino acids. Then use the structural formulas to find the common names of those amino acids, using the resources noted above. Compare each of your structural formulas with the ones in the reference list and match the IUPAC name and the structural formula with the common name.

Consult with the instructor if you have any questions about them. After you have done that, check your answers below. Then you continue with the lesson.

aminoethanoic acid

2-aminopropanoic acid

2-amino-3-hydroxypropanoic acid

2-amino-3-hydroxybutanoic acid

2,6-diaminohexanoic acid

2-amino-4-methylpentanoic acid

Answers

aminoethanoic acid	glycine
2-aminopropanoic acid	alanine
2-amino-3-hydroxypropanoic acid	serine
2-amino-3-hydroxybutanoic acid	threonine
2,6-diaminohexanoic acid	lysine
2-amino-4-methylpentanoic acid	leucine

If you would like some additional practice, try taking a few of the structural formulas and write IUPAC names for them. Then have an instructor (on-line or in the lab) check your answers. Beware that some of these are much more complex than I have indicated with the example I have chosen. You will not be held responsible for them.

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Clackamas Community College
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