Biological Synthesis of Substituted o-Aminophenols.

摘要

Polybenzoxazoles are thermally stable, high modulus polymers made by the condensation of carboxylic acids with o-aminophenols. This report summarizes research to develop methods for the biosynthesis of substituted o-aminophenols from less expensive precursors such as substituted anilines, benzidine, and o-nitrophenols. One approach has been to exploit isolated enzymes to catalyze the desired reactions. Of the four enzymes we have studied for this purpose, tyrosinase shows the most promise. This enzyme has the desired catalytic activity, catalyzing the ortho hydroxylation of several anilines and benzidines, but the reaction rate is 100-fold slower than with phenols and an exogenous reductant must be added to the reaction to inhibit the enzyme-catalyzed oxidation of the desired o-aminophenol. As an alternative to this approach, we investigated the biosynthesis of o-aminophenols via bacterial reduction of o-nitrophenols. Bacterial strain PI1, a GE isolate, catalyzes the reduction of nitroaromatic compounds. This bacterium, identified as a Group D Streptococci, has broad substrate specificity for this nitro-reductase activity and good viability under high product and substrate concentrations.