Several purification methods were tested and the optimal procedure for obtaining L-lysine a-oxidase from fungi Trichoderma sp. and its isoform (minor L-lysine a-oxidase) was worked out. The enzyme and its isoform were obtained in a homogeneous state, the. most important physicochemical properties were studied, and a number of differences between them were found. The most marked differences between L-lysine a-oxidase and its isoform were observed in the molecular weight (120 and 100 kD, respectively), in the isoelectric point (pI 4.4 and 5.6, respectively), and in the specific activity (90-95 and 17-20 U/mg) in experiments where L-lysine where used as substrate.
Key Words: L-lysine a-oxidase; L-amino acid oxidase; isoform; purification of enzyme isoforms; pysicochemieal propertiesData on the purification of the antitumor enzyme L-lysine a-oxidase (LO) from fungi Trichoderma sp. [2,5,7] as well as on some catalytic and biological properties of this enzyme [3][4][5][6] were presented in previous papers. When the composition of culture fluid of Trichoderma sp. was examined, it was found that together with the already known LO it contains another protein which can also catalyze the oxidative deamination of L-lysine and some other Lamino acids and which was dubbed minor L-lysine c~-oxidase (m-LO). Preliminary data on this new enzyme were published earlier [5].Besides working out the optimal procedure for isolating and purifying m-LO, the aim of the present study was to obtain experimental evidence of m-LO existence and to study its main physicochemical properties.
MATERIALS AND METHODSFor the separation of proteins the following chromatographic carriers were used; butyl-silochrom C-
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