Involving Opening of the Aromatic Ring

The microbiological degradation of many substances allied to the aromatic amino acids has been studied (reviews 346, 825). Thus the ring of catechol is opened to give ultimately /3-ketoadipic acid (469) via cis-cis-muconic acid (246, 813, 826)  

Analogous reactions might occur with, for example, dihydroxyphenylal-anine or its derivatives, (e.g., 568, 829). 

Among the most remarkable features of tryptophan metabolism is the widespread use of a common pathway by a wide range of organisms. Thus many microorganisms growing on tryptophan as sole carbon source metabolize it by a route very similar to that used in man, animals, insects, and probably also to a considerable extent in plants. In this discussion, therefore, evidence leading to the elucidation of the pathway will be drawn from many fields, and more detailed consideration of the individual steps will cover a range of species. 

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