Tryptophan and Phenylacetic Acid as Precursors

Phenylacetic acid is another compound which has served as a precursor of tropic acid. Good incorporations (compared with phenylalanine) of [l- C]phenylacetic acid into tropic acid have been reported. Degradations carried out on this tropic acid were consistent with all the activity being located at C-3. In view of the work with the doubly labelled phenylalanine, it is unlikely that phenylacetic acid is an intermediate between phenylalanine and tropic acid. The incorporation of phenylacetic acid can be rationalized if it is assumed that it undergoes a carboxylation leading to phenylpynivic acid and thence to phenylalanine by transamination. This reaction has been observed by Allison in ruminal bacteria and photosynthetic anaerobic bacteria. He showed that phenylalanine derived from [I- C]phenylacetic was labelled solely at C-2.  

The Reporter, in his early work, found that none of the usual one-carbcm 

Reported by S. Agurell, Abh. dtsch. Akad. Wiss. Berlin, Kl. Chem Geot., BioL, Nr. 3, 1966,538. 

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