Biosynthesis of [1-15N] L-tryptophan from 15N labeled anthranilic acid by fermentation of Candida utilis mutant.

A new method for synthesizing the labeled L-tryptophan is described in this work. L-tryptophan, labeled with 98% (15)N at position 1 was synthesized from the labeled anthranilic acid using Candida utilis mutants. The conversion ratio of (15)N of 50% was achieved. The labeled anthranilic acid was synthesized by [(15)N] phthalimide that was prepared by 99.34% [(15)N] urea and phthalic anhydride in ortho-xylene medium at 140 degrees C and under atmospheric pressure.