Amino Acids that form Fumarate

1. Phenylalanine and tyrosine: Hydroxylation of phenylalanine produces tyrosine (Fig. 1). This irreversible reaction, catalyzed by tetrahydrobiopterin-requiring phenylalanine hydroxylase (PAH), initiates the catabolism of phenylalanine. Thus, phenylalanine metabolism and tyrosine metabolism merge, leading ultimately to fumarate and acetoacetate formation. Therefore, phenylalanine and tyrosine are both glucogenic and ketogenic.

Figure 1: 7 Degradation of phenylalanine.

2. Inherited deficiencies: Inherited deficiencies in the enzymes of phenylalanine and tyrosine metabolism lead to the diseases phenylketonuria (PKU) , tyrosinemia , and alkaptonuria  as well as the condition of albinism .