title: Three-dimensional structure of homodimeric cholesterol esterase-ligand complex at 1.4 A resolution.
abstract: The three-dimensional structure of a Candida cylindracea cholesterol esterase (ChE) homodimer (534 x 2 amino acids) in complex with a ligand of proposed formula C(23)H(48)O(2) has been determined at 1.4 A resolution in space group P1 using synchrotron low-temperature data. The structure refined to R = 0.136 and R(free) = 0.169 and has revealed new stereochemical details in addition to those detected for the apo- and holo-forms at 1.9 and 2.0 A resolution, respectively [Ghosh et al. (1995), Structure, 3, 279-288]. The cholesterol esterase structure is a dimer with four spatially separated interfacial contact areas and two symmetry-related pairs of openings to an internal intradimer cavity. Hydrophobic active-site gorges in each subunit face each other across a central interfacial cavity. The ChE subunits have carbohydrate chains attached to their Asn314 and Asn351 residues, with two ordered N-acetyl-D-glucosoamine moieties visible at each site. The side chains of 14 residues have two alternative conformations with occupancy values of 0.5 +/- 0.2. For each subunit the electron density in the enzyme active-site gorge is well modeled by a C(23)-chain fatty acid.
authors.affiliation: Institute of Bioorganic Chemistry, Russian Academy of Science, Moscow, Russia.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Pletnev
authors.forename: Anthony
authors.initials: A
authors.lastname: Addlagatta
authors.forename: Zdzislaw
authors.initials: Z
authors.lastname: Wawrzak
authors.forename: William
authors.initials: W
authors.lastname: Duax
mesh_terms: D000117:Acetylglucosamine / Q000737:chemistry / Q000378:metabolism; D000595:Amino Acid Sequence; D001216:Asparagine / Q000378:metabolism; D001665:Binding Sites; D002175:Candida / Q000201:enzymology; D018360:Crystallography, X-Ray / Q000379:methods; D019281:Dimerization; D057927:Hydrophobic and Hydrophilic Interactions; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D017433:Protein Structure, Secondary; D021122:Protein Subunits; D013237:Stereoisomerism; D002787:Sterol Esterase / Q000737:chemistry* / Q000378:metabolism
chemical_list: D008024:Ligands; D021122:Protein Subunits; D001216:Asparagine; D002787:Sterol Esterase; D000117:Acetylglucosamine