Purification and Properties of a .mine cy=Ketoglutarate Transaminase from Escherichia coZi*

Putrescine can be converted to y-aminobutyraldehyde by enzymes from different sources (l-3). It. is generally believed that this conversion is catalyzed by a nonspecific diamine oxidase. The presence of such an enzyme in bacteria, however, has not been firmly established experimentally. We have previously reported that, in a mutant of Escherichia co& B selected to grow on putrescine as the sole source of carbon and nitrogen, the conversion of putrescine to y-aminobutyraldehyde was catalyzed by a transaminase (4). In this paper, the purification and the properties of this enzyme are reported. The isolation and the characteristics of this mutant strain of Escherichia coli are reported elsewhere (5).