LOW-SPECIFICITY L-THREONINE ALDOLASE OF PSEUDOMONAS SP. NCIMB-10558 -PURIFICATION, CHARACTERIZATION AND ITS APPLICATION TO BETA-HYDROXY-ALPHA-AMINO ACID SYNTHESIS

Low-specificity L-threonine aldolase, catalyzing the reversible cleava ge/condensation reaction between L-threonine/L-allo-threonine and glyc ine plus acetaldehyde, was purified to homogeneity from Pseudomonas sp . NCIMB 10558. The enzyme has an apparent molecular mass of approximat ely 145 kDa and consists of four identical subunits with a molecular m ass of 35 kDa. The enzyme, requiring pyridoxal-5'-phosphate as a coenz yme, is strictly L-specific at the alpha position, whereas it can not distinguish between threo and erythro forms at the beta position. Besi des the reversible cleavage/condensation of threonine, the enzyme also catalyzes the reversible interconversion between glycine plus various aldehydes and L-beta-hydroxy-alpha-amino acids, including L-beta-(3,4 -dihydroxyphenyl)serine, L-beta-(3,4-methylenedioxyphenyl)serine and L -beta-phenylserine, providing a new route for the industrial productio n of these important amino acids.