Tyrosine is made by a similar transamination reaction as that seen in phenylalanine synthesis. Figure 12 - Synthesis of tyrosine. Tryptophan Trytophan synthesis is complex and involves 5 steps from chorismate. Glutamate donates an amine group in the first step of the pathway and pyruvate is lost from chorismate. In the next threes steps a ribose sugar is added, this eventually contributes to the 5 membered ring of tryptophan.
Energy is contributed to the process in the form of hydrolysis of pyrophosphate.
This hydrolysis helps drive the addition of the ribose sugar in the second step of the reaction. In the last step of the pathway serine serves as the donor of the a carbon amino group of tryptophan. Figure 13 - Synthesis of tryptophan. Unique pathways cysteine, methionine, proline, histidine and arginine These pathways involve something unusual, either the structure of the amino acid is different enough than the other common amino acids, or sulfur is involved in their synthesis. In any case, unique enzymes are involved in every step of the way.