You may recall that metabolism (both catabolism and anabolism) of fatty acids involved intermediates called 3-keto acids. The catabolism of amino acids involves intermediates called a-keto acids. Remember that the more complete generic name for amino acids is "a-amino carboxylic acids." That is, they are carboxylic acids that have an amino group as one of the substituents on their a-carbon (the other 2 substituents are a hydrogen and an R group). If you replace the amino group and H substituents on the a-carbon with a double bond to an oxygen, you will have turned the amino acid into its corresponding a-keto acid. Three amino acids that play pivotal roles in amino acid catabolism are glutamate, alanine and aspartate. To prepare yourself for today's class, draw each of these amino acids. Write the amino acid's name next to the structure you've drawn, and indicate its a-carbon (circle it or draw an arrow pointing to it). Then draw the corresponding a-keto acid. Each of these three a-keto acids is an intermediate that you've already encountered in our study of carbohydrate metabolism! Identify each of the three a-keto acids that you've drawn and write its name next to its structure.