Purification and characterization of L-2,4-diaminobutyrate decarboxylase from Acinetobacter calcoaceticus.
Acinetobacter calcoaceticus ATCC 23055 produces a large amount of 1,3-diaminopropane under normal growth conditions. The enzyme responsible, L-2,4-diaminobutyrate (DABA) decarboxylase (EC 4.1.1.-), was purified to electrophoretic homogeneity from this bacterium. The native enzyme had an M(r) of approximately 108,000, with a pI of 5.0, and was a dimer composed of identical or nearly identical subunits with apparent M(r) 53,000. The enzyme showed hyperbolic kinetics with a Km of 1.59 mM for DABA and 14.6 microM for pyridoxal 5'-phosphate as a coenzyme. The pH optimum was in the range 8.5-8.75, and Ca2+ gave a much higher enzyme activity than Mg2+ as a cationic cofactor. N-gamma-Acetyl-DABA, 2,3-diaminopropionic acid, ornithine and lysine were inert as substrates. The enzyme was different in subunit structure, N-terminal amino acid sequence and immunoreactivity from the DABA decarboxylase of Vibrio alginolyticus previously described.
Yamamoto
S
S
Faculty of Pharmaceutical Sciences, Okayama University, Japan.
Tsuzaki
Y
Y
Tougou
K
K
Shinoda
S
S
D016954:Acinetobacter calcoaceticus / Q000201:enzymology*; D000595:Amino Acid Sequence; D002262:Carboxy-Lyases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D002412:Cations / Q000378:metabolism; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D011732:Pyridoxal Phosphate / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature; D014733:Vibrio / Q000201:enzymology*
D002412:Cations; D011732:Pyridoxal Phosphate; C062274:2,4-diaminobutyric acid decarboxylase; D002262:Carboxy-Lyases