Kinetic characteristics of L-lysine ?- oxidase from Trichoderma cf. aureoviride Rifai VKM F-4268D: Substrate specificity and allosteric effects.

ABSTRACT: The present work aims to investigate the kinetic characteristics of homodimer enzyme L-lysine ?-oxidase from Trichoderma cf. aureoviride Rifai VKM F-4268D, taking into account allosteric effects. The enzyme was first shown to reveal positive cooperativeness, h=2.05±0.15. Using additional opportunities of Hill coefficient the value of the Michaelis-Menten constant has been estimated, Km=1.015?10-5?, indicating high strength of substrate binding to the active site of each subunit. High selectivity and absolute L-stereospecificity of the enzyme were shown. The inhibition of L-lysine conversion by non-cleavable lysine analogs as well as the reaction product was found out to take place. These effects have been evaluated only as the inhibition coefficients (%). A more detailed study of these inhibition effects was complicated because of the cooperativeness of enzyme subunits mentioned above. The kinetic scheme of L-lysine ?-oxidase was proposed involving parallel-subsequent action of each of two subunits in the catalytic act. We think that the results obtained will be useful for studying the kinetic properties of other multi-subunit enzymes and improve understanding of the mechanisms of their action.

SUBMITTER: Krupyanko VI 

PROVIDER: S-EPMC5632708 | biostudies-other | 2017 Mar

REPOSITORIES: biostudies-other