Citizendium - a community developing a quality, comprehensive compendium of knowledge, online and free.
Click here to join and contribute
CZ thanks our previous donors. Donate here. Treasurer's Financial Report


From Citizendium
Jump to: navigation, search
This article is a stub and thus not approved.
Main Article
Related Articles  [?]
Bibliography  [?]
External Links  [?]
Citable Version  [?]
This editable Main Article is under development and subject to a disclaimer.
(CC) Image: David E. Volk
Phenylalanine, one of the twenty common amino acids.

Phenylalanine, abbreviated Phe or F, is one of the twenty common -amino acids used by living organisms to build proteins. It is one of four aromatic amino acids with histidine, tyrosine and tryptophan. It is very hydrophobic is found almost exclusively buried within hydrophobic patches in protein structures. When aspartame was first introduced (as Nutrisweet) it caused the deaths of several people suffering from phenylketonuria due to the metabolic degradation of aspartame to phenylalanine, which phenylketonurics cannot metabolize.


(CC) Image: David E. Volk
Bacterial biosynthesis of phenylalanine from chorismate.

Both phenylalanine and tyrosine are essential amino acids that are biosynthesized by bacteria starting from chorismate then prephenate, at which point their syntheses diverge. Chorismate itself results from a six-step reaction starting from erythrose-4-phosphate. For the synthesis of phenylalanine, chorismate is converted to prephenate by a mutase. Prephenate is then dehydrated and decarboxylated to provide phenylpyruvate. In the synthesis of tyrosine, this step is an oxidative decarboxylation reaction that leaves the hydroxyl group on the aromatic ring. Finally, the -keto acid is converted to phenylalanine by a transamination reaction.