18] l-kynurenine transaminase from Hansenula schneggii

Abstract

Publisher Summary This chapter provides an overview of L-kynurenine transaminase from Hansenula schneggii. L - Kynurenine - α - ketoglutarate aminotransferase catalyzes the transfer of the α -amino group of L-kynurenine to α-ketoglutarate to yield L-glutamate and o-aminobenzoylpyruvic acid, which is immediately converted to the intramolecularly dehydrated and cyclized form, kynurenic acid. The chapter describes the assay method, purification procedures, and general properties of L-kynurenine-α-ketoglutarate aminotransferase of yeast, Hansenula schneggii. The assay method routinely employed is based on the spectrophotometric determination of kynurenic acid formed. L-Kynurenine consumption is determined by measuring the rate of decrease in absorbance at 370 nm because of the deamination of L-kynurenine. The purification procedure consists of several steps comprising preparation of crude extract, polyethyleneimine treatment, DEAE-cellulose column chromatography, and BioGel P-300 column chromatography. Approximately 930-fold purification is achieved with an overall yield of 40%.