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ARS Home » Research » Publications at this Location » Publication #227380

Title: Beta-D-xylosidase from Selenomonas ruminantium: thermodynamics of enzyme-catalyzed and noncatalyzed reactions

item Jordan, Douglas
item Braker, Jay

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/18/2008
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Beta-D-xylosidase/alpha-L-arabinofuranosidase from Selenomonas ruminantium (SXA) is the most active enzyme known for catalyzing hydrolysis of 1,4-beta-D-xylooligosaccharides to D-xylose. Temperature dependence for hydrolysis of 4-nitrophenyl-beta-D-xylopyranoside (4NPX), 4-nitrophenyl-alpha-L-arabinofuranoside (4NPA), and 1,4-beta-D-xylobiose (X2) was determined on and off (knon) the enzyme at pH 5.3, which lies in the pH-independent region for kcat and knon. Rate enhancements (kcat/knon) for 4NPX, 4NPA, and X2 are 4.3 x 10**11, 2.4 x 10**9, and 3.7 x 10**12, respectively, at 25 deg C and increase with decreasing temperature. Relative parameters kcat**4NPX/kcat**4NPA, kcat**4NPX/kcat**X2, and (kcat/Km)**4NPX/(kcat/Km)**X2 increase and (kcat/Km)**4NPX/(kcat/Km)**4NPA, (1/Km)**4NPX/(1/Km)**4NPA, and (1/Km)**4NPX/(1/Km)**X2 decrease with increasing temperature.