In the human body, the amino acid phenylalanine is normally processed by an enzyme that converts it to cinnamic acid. infants with phenylketonuria (pku) have a defective enzyme, resulting in a buildup of phenylalanine that can damage a developing brain. people with pku must minimize phenylalanine in their diet by avoiding protein-rich foods and the artificial sweetener aspartame. recent research explores a treatment for pku that uses tiny lipid-bilayer packages called posomes to deliver an alternate enzyme that can convert phenylalanine to cinnamic acid (adv. funct. mater. 2015, 25, 3860- predict the number of signals and the number of protons giving rise to each signal in the h nmr spectra of both phenylalanine and cinnamic acic. enzyme oh nh2 cinnamic acid phenylalanine has the 1h nmr spectrum with signals. signals. cinnamic acid has the 1h nmr spectrum