FORMATION OF A 3-(PHENYLAMINO)ALANINE CONTAMINANT IN EMS-ASSOCIATED L-TRYPTOPHAN

Chemical studies were conducted to determine the origin of the 3-(phen ylamino)alanine (PAA) contaminant in EMS-associated L-tryptophan sampl es. Anthranilic acid, a biosynthetic precursor of the L-tryptophan, wa s heated at 80 degrees C for 6 h under acidic conditions to produce 14 0 mu g of aniline/g of anthranilic acid. The presence of aniline was v erified by HPLC-UV and GC-MS. PAA (160 mu g of PAA/g of aniline) was p roduced by heating aniline and serine at 80 degrees C for 6h under bas ic conditions. PAA was confirmed by HPLC-UV and LC-MS. These results s uggest that PAA could be formed under the fermentation and purificatio n conditions used to produce L-tryptophan on an industrial scale.