TY - JOUR
T1 - Highly active β-xylosidases of glycoside hydrolase family 43 operating on natural and artificial substrates
AU - Jordan, Douglas B.
AU - Wagschal, Kurt
AU - Grigorescu, Arabela A.
AU - Braker, Jay D.
N1 - Funding Information:
Acknowledgment Trypsin digestion and LC-MS/MS analysis was performed at the Wistar Proteomics Facility. Sedimentation equilibrium experiments were conducted at Northwestern University, Keck Biophysics Facility, supported by a Cancer Center Grant (NCI CA060553). Mention of trade names or commercial products in this report is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. USDA is an equal opportunity provider and employer.
PY - 2013/5
Y1 - 2013/5
N2 - The hemicellulose xylan constitutes a major portion of plant biomass, a renewable feedstock available for conversion to biofuels and other bioproducts. β-xylosidase operates in the deconstruction of the polysaccharide to fermentable sugars. Glycoside hydrolase family 43 is recognized as a source of highly active β-xylosidases, some of which could have practical applications. The biochemical details of four GH43 β-xylosidases (those from Alkaliphilus metalliredigens QYMF, Bacillus pumilus, Bacillus subtilis subsp. subtilis str. 168, and Lactobacillus brevis ATCC 367) are examined here. Sedimentation equilibrium experiments indicate that the quaternary states of three of the enzymes are mixtures of monomers and homodimers (B. pumilus) or mixtures of homodimers and homotetramers (B. subtilis and L. brevis). k cat and k cat/K m values of the four enzymes are higher for xylobiose than for xylotriose, suggesting that the enzyme active sites comprise two subsites, as has been demonstrated by the X-ray structures of other GH43 β-xylosidases. The K i values for d-glucose (83.3-357 mM) and d-xylose (15.6-70.0 mM) of the four enzymes are moderately high. The four enzymes display good temperature (K t 0.5 ∼ 45 C) and pH stabilities (>4.6 to <10.3). At pH 6.0 and 25 C, the enzyme from L. brevis ATCC 367 displays the highest reported k cat and k cat/K m on natural substrates xylobiose (407 s -1, 138 s-1 mM-1), xylotriose (235 s -1, 80.8 s-1 mM-1), and xylotetraose (146 s-1, 32.6 s-1 mM-1).
AB - The hemicellulose xylan constitutes a major portion of plant biomass, a renewable feedstock available for conversion to biofuels and other bioproducts. β-xylosidase operates in the deconstruction of the polysaccharide to fermentable sugars. Glycoside hydrolase family 43 is recognized as a source of highly active β-xylosidases, some of which could have practical applications. The biochemical details of four GH43 β-xylosidases (those from Alkaliphilus metalliredigens QYMF, Bacillus pumilus, Bacillus subtilis subsp. subtilis str. 168, and Lactobacillus brevis ATCC 367) are examined here. Sedimentation equilibrium experiments indicate that the quaternary states of three of the enzymes are mixtures of monomers and homodimers (B. pumilus) or mixtures of homodimers and homotetramers (B. subtilis and L. brevis). k cat and k cat/K m values of the four enzymes are higher for xylobiose than for xylotriose, suggesting that the enzyme active sites comprise two subsites, as has been demonstrated by the X-ray structures of other GH43 β-xylosidases. The K i values for d-glucose (83.3-357 mM) and d-xylose (15.6-70.0 mM) of the four enzymes are moderately high. The four enzymes display good temperature (K t 0.5 ∼ 45 C) and pH stabilities (>4.6 to <10.3). At pH 6.0 and 25 C, the enzyme from L. brevis ATCC 367 displays the highest reported k cat and k cat/K m on natural substrates xylobiose (407 s -1, 138 s-1 mM-1), xylotriose (235 s -1, 80.8 s-1 mM-1), and xylotetraose (146 s-1, 32.6 s-1 mM-1).
KW - Biomass
KW - Five-bladed propeller
KW - GH43
KW - Glycoside hydrolase
KW - Transportation fuel
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U2 - 10.1007/s00253-012-4475-4
DO - 10.1007/s00253-012-4475-4
M3 - Article
C2 - 23053115
AN - SCOPUS:84877736470
VL - 97
SP - 4415
EP - 4428
JO - Applied Microbiology and Biotechnology
JF - Applied Microbiology and Biotechnology
SN - 0175-7598
IS - 10
ER -