Chapter 4

Individuals with phenylketonuria must avoid dietary phenylalanine because they are unable to convert phenylalanine to tyrosine. Look up this condition and find out what happens if phenylalanine accumulates in the body. Would you advise a person with phenylketonuria to consume foods sweetened with aspartame? Why or why not?

Amino acids are frequently used as buffers. Describe the pH range of acceptable buffering behavior for the amino acids alanine, histidine, aspartic acid, and lysine.

Although the other common amino acids are used as buffers, cysteine is rarely used for this purpose. Why?

Draw all the possible isomers of threonine and assign \((R, S)\) nomenclature to each.