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538 a.a.
Key reference
DOI no: 10.1016/j.abb.2008.03.007 Arch Biochem Biophys 474:157-166 (2008) PubMed id: 18374656
Structure of the two-subsite beta-d-xylosidase from Selenomonas ruminantium in complex with 1,3-bis[tris(hydroxymethyl)methylamino]propane. J.S.Brunzelle, D.B.Jordan, D.R.McCaslin, A.Olczak, Z.Wawrzak. ABSTRACT
The three-dimensional structure of the catalytically efficient beta-xylosidase from Selenomonas ruminantium in complex with competitive inhibitor 1,3-bis[tris(hydroxymethyl)methylamino]propane (BTP) was determined by using X-ray crystallography (1.3A resolution). Most H bonds between inhibitor and protein occur within subsite -1, including one between the carboxyl group of E186 and an N group of BTP. The other N of BTP occupies subsite +1 near K99. E186 (pK(a) 7.2) serves as catalytic acid. The pH (6-10) profile for 1/K(i)((BTP)) is bell-shaped with pK(a)'s 6.8 and 7.8 on the acidic limb assigned to E186 and inhibitor groups and 9.9 on the basic limb assigned to inhibitor. Mutation K99A eliminates pK(a) 7.8, strongly suggesting that the BTP monocation binds to the dianionic enzyme D14(-)E186(-). A sedimentation equilibrium experiment estimates a K(d) ([dimer](2)/[tetramer]) of 7 x 10(-9)M. Similar k(cat) and k(cat)/K(m) values were determined when the tetramer/dimer ratio changes from 0.0028 to 26 suggesting that dimers and tetramers are equally active forms.
Literature references that cite this PDB file's key reference
PubMed id Reference
18953511 D.B.Jordan, and J.D.Braker (2009).
Beta-D-xylosidase from Selenomonas ruminantium: thermodynamics of enzyme-catalyzed and noncatalyzed reactions.Appl Biochem Biotechnol, 155, 330-346.
19269961 R.Carapito, A.Imberty, J.M.Jeltsch, S.C.Byrns, P.H.Tam, T.L.Lowary, A.Varrot, and V.Phalip (2009).
Molecular Basis of Arabinobio-hydrolase Activity in Phytopathogenic Fungi: CRYSTAL STRUCTURE AND CATALYTIC MECHANISM OF FUSARIUM GRAMINEARUM GH93 EXO-{alpha}-L-ARABINANASE.J Biol Chem, 284, 12285-12296.
PDB codes: 2w5n 2w5o The most recent references are shown first. Citation data come partly from CiteXplore and partly from an automated harvesting procedure. Note that this is likely to be only a partial list as not all journals are covered by either method. However, we are continually building up the citation data so more and more references will be included with time. Where a reference describes a PDB structure, the PDB codes are shown on the right.
