AMINE OXIDASES FROM ASPERGILLUS-NIGER - IDENTIFICATION OF A NOVEL FLAVIN-DEPENDENT ENZYME

Upon induction with various amine sources, two different amine oxidase s are expressed in the filamentous fungus Aspergillus niger. The enzym es which can be separated by anion exchange chromatography exhibit a s imilar substrate specificity pattern. From cofactor and inhibitor anal ysis it was found that one amine oxidase is identical to the earlier r eported copper-containing amine oxidase (Yamada, H., Adachi, O. and Og ata, K. (1965) Agric. Biol. Chem. 29, 912-917) with 6-hydroxydopa (TOP A) quinone as the active site cofactor. The second form is a hitherto unknown flavoprotein of 55 kDa, which shows many of the characteristic properties of the mammalian monoamine oxidases (MAO). From substrate specificity and inhibitor susceptibility, it is suggested that the mon oamine oxidase from A. niger (MAO-N) is a prototype of the two mammali an enzymes, MAO-A and MAO-B. A partial cDNA clone which encodes an ami no-terminal peptide of 53 amino acid residues was identified by lambda gt11 immunoscreening. The consensus sequence of the putative flavin a denine dinucleotide (FAD) binding site is found within this sequence.