PIGMENT FORMATION FROM L-TRYPTOPHAN BY A PARTICULATE FRACTION FROM AN ACHROMOBACTER SPECIES

Particles obtained from an Achromobacter species catalyzes the oxidation of l-tryptophan yielding a red pigment. The only exogenous requirements are l-tryptophan, oxygen, and manganese salts. Pigment formation appears to be the result of a two-step reaction. A particulate bound enzyme catalyzes the oxidative deamination of l-tryptophan to indolepyruvate which undergoes further oxidation to a highly chromogenic compound. The latter reaction occurs spontaneously when indolepyruvate is oxidized at pH 7.5 in the presence of manganese salts. The enzyme catalyzing the initial reaction may also catalyze the oxidation of several other l-amino acids. It is likely that this enzyme is a general l-amino acid oxidase. The pigment has been purified by extraction with chloroform and column chromatography. Spectrophotometric analysis of the pigment revealed maxima absorbancies at 500 and 290 mμ with ε{lunate}m values of 4,080 and 13,500, respectively. Reduction of the pigment with Na2SO3 resulted in a shift in the λmax from 500 to 390 mμ. Further analytical data including elemental analysis and infrared spectral analysis indicate the chemical structure of this compound to be sodium β-3H-indolydenopyruvate monohydrate. © 1969.