PURIFICATION AND CHARACTERIZATION OF OLIGOMERIC SPECIES OF AN AROMATIC AMINO ACID AMINOTRANSFERASE FROM LACTOCOCCUS LACTIS SUBSP. LACTIS S3

摘要: Two oligomeric species of an aromatic amino acid aminotransferase (Ar-AT) were purified and characterized from Lactococcus lactis subsp. S3. The more abundant species, Ar-AT1, was over 2,200-fold with a 3% recovery. molecular masses Ar-AT1 determined to be 42 kDa 84 by SDS-PAGE gel filtration, respectively. the less Ar-AT2, 170 kDa, Both Ar-AT2 have identical N-terminal sequences which indicates they are homodimeric homotetrameric forms same enzyme. Ar-ATs catalyze e pyridoxal-5'-phosphate dependent transamination Phe, Tyr, Trp, Leu Met utilizing α-ketoglutarate as acceptor. Km values two for Tyr Phe ranged 0.65 2.43 mM. However, differences observed in pI specific activities between Ar-ATs. 4.63 3.93, Vmax/Km ratios three-fold greater than that indicating is catalytically efficient on these acids Ar-AT1.