1WC7

Structure of a Pseudomerohedrally Twinned Monoclinic Crystal Form of a Pyridoxal Phosphate-Dependent Catalytic Antibody

(2005) Acta Crystallogr D Biol Crystallogr 61: 472

• PubMed: 15805602 Search on PubMed
• DOI: https://doi.org/10.1107/S0907444905003331
• Primary Citation of Related Structures:  
  1WC7


• PubMed Abstract: 
  

  The purification, crystallization and structure determination at 2.3 A resolution of the complex of the pyridoxal-5'-phosphate (PLP) dependent catalytic antibody 15A9 with a phosphopyridoxyl-L-alanine (PPL-L-alanine) substrate analogue are described. The crystal belongs to space group P2(1), with two molecules in the asymmetric unit related by non-crystallographic symmetry. The unit-cell parameters are a = 63.5, b = 81.7, c = 79.3 A and beta is fortuitously 90 degrees . Refinement of the structure converged at unacceptably high R factors. Although the traditional analysis of intensity distribution did not indicate twinning, pseudomerohedral twinning was revealed by a newer test based on local intensity differences [Padilla & Yeates (2003), Acta Cryst. D59, 1124-1130]. When the potential twinning operator was included in SHELX, the structure could be satisfactorily refined with a twinning fraction of 0.46, indicating a nearly perfect hemihedrally twinned crystal. One of the active sites is occupied by the phosphopyridoxyl-L-alanine ligand, while one iodide ion mimics the cofactor phosphate group in the other. Four other iodide ions are present in the structure: two are involved in specific intermolecular contacts and two dictate the conformation of the CDRH3 loop in each molecule.

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Organizational Affiliation: 

Laboratoire d'Enzymologie et de Biochimie Structurales, Bâtiment 34, CNRS, 1 Avenue de la Terrasse, 91190 Gif-sur-Yvette, France. [email protected]