2 research outputs found
Discovery of an l‑Fucono-1,5-lactonase from cog3618 of the Amidohydrolase Superfamily
A member of the amidohydrolase superfamily, BmulJ_04915
from <i>Burkholderia multivorans</i>, of unknown function
was determined
to hydrolyze a series of sugar lactones: l-fucono-1,4-lactone, d-arabino-1,4-lactone, l-xylono-1,4-lactone, d-lyxono-1,4-lactone, and l-galactono-1,4-lactone. The highest
activity was shown for l-fucono-1,4-lactone with a <i>k</i><sub>cat</sub> value of 140 s<sup>–1</sup> and a <i>k</i><sub>cat</sub>/<i>K</i><sub>m</sub> value of
1.0 × 10<sup>5</sup> M<sup>–1</sup> s<sup>–1</sup> at pH 8.3. The enzymatic product of an adjacent l-fucose
dehydrogenase, BmulJ_04919, was shown to be l-fucono-1,5-lactone
via nuclear magnetic resonance spectroscopy. l-Fucono-1,5-lactone
is unstable and rapidly converts nonenzymatically to l-fucono-1,4-lactone.
Because of the chemical instability of l-fucono-1,5-lactone,
4-deoxy-l-fucono-1,5-lactone was enzymatically synthesized
from 4-deoxy-l-fucose using l-fucose dehydrogenase.
BmulJ_04915 hydrolyzed 4-deoxy-l-fucono-1,5-lactone with
a <i>k</i><sub>cat</sub> value of 990 s<sup>–1</sup> and a <i>k</i><sub>cat</sub>/<i>K</i><sub>m</sub> value of 8.0 × 10<sup>6</sup> M<sup>–1</sup> s<sup>–1</sup> at pH 7.1. The protein does not require divalent cations in the
active site for catalytic activity. BmulJ_04915 is the second enzyme
from cog3618 of the amidohydrolase superfamily that does not require
a divalent metal for catalytic activity. BmulJ_04915 is the first
enzyme that has been shown to catalyze the hydrolysis of either l-fucono-1,4-lactone or l-fucono-1,5-lactone. The structures
of the fuconolactonase and the fucose dehydrogenase were determined
by X-ray diffraction methods