Structural determination of lipid-bound human blood coagulation factor IX

摘要

Human coagulation factor IX (FIX) is a serine protease which binds to a negatively charged phospholipid surface in the presence of Ca ions (Ca~(2+)). FIX two-dimensional (2-D) crystals were obtained by the lipid layer crystallisation technique under near physiological conditions. The 2-D projection map of the protein was calculated to a resolution of 3 nm using electron crystallographic analysis. The structural organisation of membrane-bound FIX is discussed and compared with the known X-ray crystallographic data.