Purification and characterization of l- allo-threonine aldolase from Aeromonas jandaei DK-39

Abstract

l- allo-Threonine aldolase ( l- allo-threonine acetaldehyde-lyase), which exhibited specificity for l- allo-threonine but not for l-threonine, was purified from a cell-free extract of Aeromonas jandaei DK-39. The purified enzyme catalyzed the aldol cleavage reaction of l- allo-threonine ( K m=1.45 mM, V max=45.2 μmol min −1 mg −1). The activity of the enzyme was inhibited by carbonyl reagents, which suggests that pyridoxal-5′-phosphate participates in the enzymatic reaction. The enzyme does not act on either l-serine or l-threonine, and thus it can be distinguished from serine hydroxy-methyltransferase ( l-serine:tetrahydrofolate 5,10-hydroxy-methyltransferase, EC 2.1.2.1) or l-threonine aldolase (EC 4.1.2.5).