Shikimic Acid to Aromatic Amino Acids

Conversion op Shikimic Acid to Aromatic Amino Acids 

The next stage in the formation of the aromatic amino acids involves the conversion of shikimic acid to prephenic acid (XV) and anthranilic acid (XVI). The conversion of prephenic acid to phenylalanine and t3Tosine, and that of anthranilic acid to tryptophan are fairly well understood and 

This phosphorylation was not inhibited by any of the end products of aromatic biosynthesis.  

The other compound, called Zl, which was much more acid-labile, was hydrolyzed to equimolar amounts of pyruvate and shikimate, and was tentatively assigned the structure of shikimate 3- or 5-enolpyruvate ether. In a more recent study, it was found that the barium salt of Zl does not absorb in the carbonyl region of the infrared absorption spectrum (no ester structure), and that it has a strong band at 8.2iu characteristic of a vinyl ether. It is oxidized very rapidly by periodate, giving rise to an unstable compound with maximum absorption at 235 m i ( = 4000). A similar unstable chromophore, most likely having the structure XVII, was produced by periodate oxidation of shikimate 3-phosphate but not of shikimate 5-phosphate. (3-Methyl-crotonaldehyde shows Xm 235, t = 6700. ) These observations suggest that Zl is shikimate 3-enolpyruvate ether (XVIII). 

Since the mutants which accumulated Zl accmnulated a trace of shiki- 

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VII. Conversion of Shikimic Acid to Aromatic Amino Acids. 259... 

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