title: Influence of the N-terminal peptide on the cocrystallization of a thermophilic endo-β-1,4-glucanase with polysaccharide substrates.
abstract: It is well known that protein cocrystallization is affected by several parameters such as the ratio of the protein to the ligand, the reservoir solution, the pH and the temperature. Previously, spatial blocking by the N-terminus was observed in the active site in the crystal structure of the native protein of a thermostable endoglucanase from the thermophilic bacterium Fervidobacterium nodosum Rt17-B1 (FnCel5A). It was speculated that the N-terminal α-helix might form interactions with the substrate-binding residues and it was believed that this spatial block is special to some extent. In order to confirm the effect on cocrystallization, two N-terminally truncated variants of FnCel5A were constructed, purified and cocrystallized at 291 K. A crystal of FnCel5AND_12-343 in complex with cellobiose was obtained using PEG 8000 as a precipitant. A 2.2 Å resolution data set was collected. This crystal form (space group P4(1)2(1)2, unit-cell parameters a = b = 47.3, c = 271.4 Å) differed from that of the native protein. One molecule is assumed to be present per asymmetric unit, which gives a Matthews coefficient of 2.05 Å(3) Da(-1).
authors.affiliation: Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, Jilin University, Changchun 130023, People's Republic of China.
authors.forename: Baisong
authors.initials: B
authors.lastname: Zheng
authors.forename: Wen
authors.initials: W
authors.lastname: Yang
authors.forename: Yuguo
authors.initials: Y
authors.lastname: Wang
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Lou
authors.forename: Yan
authors.initials: Y
authors.lastname: Feng
mesh_terms: D001419:Bacteria / Q000201:enzymology*; D002480:Cellulase / Q000737:chemistry* / Q000378:metabolism; D003460:Crystallization; D018360:Crystallography, X-Ray; D011134:Polysaccharides / Q000737:chemistry* / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D011134:Polysaccharides; D002480:Cellulase
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