459 



Indoles 



nated and the indole so formed combines with L-serine to 

 fonn L-tryptophan : 



COOH 



COOH 



r^ 



NH' 



CH— CH— CH— CH— CH.— O— PO3H2 



' I 1 



NH. OH OH 



Anthranilic Acid N-(2-Carboxyphenyl)-l -aminoribose-5-phosphate 



CH— CH- CH, 



J 



' \ I I Triose phosphate 

 OH OH O— POaHj ^ 



'OO 



L-Serine 



lndolyl-3-glycerol Phosphate 



a? 



CHo— CH— COOH 

 NHo 



L-Tryptophan 



N-Fructosylanthranilic acid has been isolated from a 

 yeast, and it may be another intennediate in indole syn- 

 thesis. In this case a tetrose would be eliminated. If 

 pentoses and hexoses can both be used in reactions with 

 anthranilic acid, perhaps tetroses can be as well. This 

 possibility is emphasized by Wenkert" in a discussion of 

 alkaloid biosynthesis. A reaction of this sort might ex- 

 plain the frequent occurrence in nature of indole deriva- 

 tives with two carbon atom side-chains in the 3-position. 

 In other words the indole biosynthesis could be general- 

 ized: 



-Ernest Wenkert, Experientia 15 165 (1959). 



