Properties of L-Lysine ε-Dehydrogenase from Agrobacterium tumefaciens

Lysine ε -dehydrogenase, which has been purified to homogeneity from the extract of Agrobacterium tumefaciens ICR 1600, had a molecular weight of approximately 78,000 and consisted of two subunits identical in molecular weight (about 39,000). The enzyme showed a high substrate specificity. In additi...

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Bibliographic Details
Published in:Journal of biochemistry (Tokyo) 1989, Vol.105 (6), p.1002-1008
Main Authors: Misono, Haruo, Hashimoto, Hiroyuki, Uehigashi, Haruhiko, Nagata, Shinji, Nagasaki, Susumu
Format: Article
Language:English
Subjects:
Agrobacterium tumefaciens
Amino Acids - analysis
Analytical, structural and metabolic biochemistry
Bacterial Proteins - analysis
Biological and medical sciences
Chemical Phenomena
Chemistry, Physical
Enzymes and enzyme inhibitors
Fundamental and applied biological sciences. Psychology
Hydrogen-Ion Concentration
Isoelectric Focusing
Molecular Weight
Oxidoreductases
Rhizobium - enzymology
Substrate Specificity
Ultracentrifugation
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Summary:Lysine ε -dehydrogenase, which has been purified to homogeneity from the extract of Agrobacterium tumefaciens ICR 1600, had a molecular weight of approximately 78,000 and consisted of two subunits identical in molecular weight (about 39,000). The enzyme showed a high substrate specificity. In addition to L-lysine, S-(β-aminoethyl)-L-cysteine was deaminated by the enzyme, but to a far lesser extent. NAD+ and some NAD+ analogs (deamino-NAD+ and 3-acetylpyridine-NAD+) served as a cofactor. The pH optimum was at about 9.7 for the deamination of L-lysine. Although the NAD+ saturation curve was hyperbolic, a sigmoid saturation curve for L-lysine was obtained with the diluted enzyme solution, in which the dimeric enzyme was predominant. The reversible association of the enzyme to the tetramer was induced either by increasing the enzyme concentration or by addition of L-lysine. The preincubation of the enzyme with 5 mM L-lysine resulted in a 2-fold increase in the activity and gave a hyperbolic saturation curve for L-lysine. Upon modification of SH groups of the enzyme with DTNB, neither the interconversion between the dimer and the tetramer nor the activation by L-lysine occurred. These results indicated that the dimeric enzyme was activated by L-lysine and the activation resulted from the association of two dimeric enzymes to form a tetramer.
ISSN:0021-924X
1756-2651
DOI:10.1093/oxfordjournals.jbchem.a122757