Purification and characterization of an extracellular alpha-D-glucuronidase from Phlebia radiata.
Alpha-D-glucuronidase was isolated from the culture filtrate of Phlebia radiata grown on wheat bran and purified to homogeneity by chromatographic methods. The final enzymic preparation was purified 65-fold with an activity yield of 58%; it showed a high level of specific activity (over 23,000 nkat/mg protein). The molecular and hydrolytic properties of the purified enzyme were studied. The secreted alpha-glucuronidase had a molecular weight of 110 kDa, as established by gel permeation chromatography (GP HPLC), had a determined pI just below 4.4, and was stable at pH 5.5 for prolonged times. The carbohydrate content in protein molecules was found to be 15%. The activity of alpha-D-glucuronidase peaked at pH 3,8 and 60 degrees C with aldouronic acids preparation as the substrate. The Michaelis-Menten constant (K(m)), the maximum reaction velocity (V(max)), and the activation energy (E(a)) were 0.18 mM, 0.13 microM/min and 5.91 kJ/mol, respectively. The alpha-glucuronidase was active mainly on small substituted xylooligomers. When this enzyme was used with endoxylanase for the degradation of oat xylan, synergistic effects were observed.
Mierzwa
Małgorzata
M
Department of Biochemistry, Maria Curie-Skłodowska University, Lublin, Poland.
Tokarzewska-Zadora
Joanna
J
Deptuła
Tomasz
T
Rogalski
Jerzy
J
Szczodrak
Janusz
J
D001673:Biodegradation, Environmental; D006026:Glycoside Hydrolases / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification; D020072:Polyporales / Q000201:enzymology*; D014990:Xylans / Q000737:chemistry
D014990:Xylans; D006026:Glycoside Hydrolases; C096734:alpha-glucuronidase