title: Crystal structure of the unactivated ribulose 1,5-bisphosphate carboxylase/oxygenase complexed with a transition state analog, 2-carboxy-D-arabinitol 1,5-bisphosphate.
abstract: The crystal structure of unactivated ribulose 1,5-bisphosphate carboxylase/oxygenase from Nicotiana tabacum complexed with a transition state analog, 2-carboxy-D-arabinitol 1,5-bisphosphate, was determined to 2.7 A resolution by X-ray crystallography. The transition state analog binds at the active site in an extended conformation. As compared to the binding of the same analog in the activated enzyme, the analog binds in a reverse orientation. The active site Lys 201 is within hydrogen bonding distance of the carboxyl oxygen of the analog. Loop 6 (residues 330-339) remains open and flexible upon binding of the analog in the unactivated enzyme, in contrast to the closed and ordered loop 6 in the activated enzyme complex. The transition state analog is exposed to solvent due to the open conformation of loop 6.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles 90024-1570.
authors.forename: K Y
authors.initials: KY
authors.lastname: Zhang
authors.forename: D
authors.initials: D
authors.lastname: Cascio
authors.forename: D
authors.initials: D
authors.lastname: Eisenberg
mesh_terms: D001665:Binding Sites; D003460:Crystallization; D018360:Crystallography, X-Ray; D004789:Enzyme Activation; D006860:Hydrogen Bonding; D010428:Pentosephosphates / Q000737:chemistry / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D010947:Plants, Toxic; D011487:Protein Conformation; D012273:Ribulose-Bisphosphate Carboxylase / Q000737:chemistry* / Q000378:metabolism; D013402:Sugar Alcohols / Q000737:chemistry / Q000378:metabolism*; D014026:Nicotiana / Q000737:chemistry
chemical_list: D010428:Pentosephosphates; D010710:Phosphates; D013402:Sugar Alcohols; C032687:2-carboxyarabinitol 1,5-biphosphate; D012273:Ribulose-Bisphosphate Carboxylase