The structure of human complement factor I

Authors: Pietro Roversi (University of Oxford) , Steven Johnson (University of Oxford)
Co-authored by industrial partner: No

Type: Conference Paper
Conference: Collaborative Computational Project No. 4 (CCP4)
Peer Reviewed: No

State: Published (Approved)
Published: January 2011

Abstract: When the number of overlapping lattices ntwins present in a merohedrally twinned crystal sample is greater than 2, the twinned diffraction intensities need analysing with a formalism that goes beyond the more familiar one used in the case of hemihedral twinning (ntwins =2). The special case of ntwins=4 aka tetartohedral twinning, will be summarised and discussed, with examples taken from the recent literature. Particular attention will be given to the fact that tetartohedral twinning is almost invariably associated with 222 rotational non-crystallographic symmetry (NCS), and thus is often a special case of a general phenomenon where the twinning operators coincide with the rotational part of the NCS. The available refinement and detwinning strategies in the Refmac5 and CNS computer programs will be discussed, and the recent crystal structure determination and refinement of human Complement Factor I from tetartohedrally twinned intensities will be illustrated.

Subject Areas: Chemistry

Instruments: I02-Macromolecular Crystallography , I03-Macromolecular Crystallography , I04-1-Macromolecular Crystallography (fixed wavelength)