To characterize the aromatic aminotransferase activity cell free ext,racts of Candida maltosa were chromatographed on DEAE-cellulose, PAAG electrophorese, and gel filtration, respectively.Three active fractions could be separated: AAT I was constitutively synthesized, AAT I1 appears to be regulated by the general control of amino acid biosynthesis, a result which suggests its probable role in phenylalanine/tyrosine biosynthesis, and AAT 111 was inducible by tryptophan, phenylalanine, and/or tyrosine. Gel filtration analyses indicate that aromatic aminotransferases have molecular weights of 73,000, 85,000, and 105,000, respectively. All three enzymes showed overlapping specificities, each capable of transamination with phenylpyruvate, 4-hydroxyphenylpyruvate, prephenate, or indolepyruvate and the corresponding amino acids, but they were slowly active to glutamate and 2-oxoglutarate. The apparent MICHAELIS constants were determined and the possibilities of the enzyme reactions in the organism were discussed.Die Aininotransferasen stellen zumeist Enzyme dar, die sich durch eine breite Substratspezifitat auszeichnen. Auf Grund der dadurch bedingten uberlappenden Funktionen ist es haufig schwierig, sie in bestimnite biochemische Wege einzuordnen. Hinzu kommt noch, daB sie durch ihre Eigenschaft, die Enzynireaktion reversibel gestalten zu konnen, in der Lage sind, sowohl synthetische als auch katabole Prozesse zu katalysieren (JENSEN u. CALHOUN 1981).