Was purified from human plasma by a modification of a GMBS Technical Information published process (29). The steps included barium citrate depletion on the vitamin K proteins, four two polyethylene glycol precipitation, DEAESephadex column chromatography, euglobulin precipitation, gel filtration on Sephacryl300, dextran sulfateSepharose column chromatography, and rabbit anticontaminant IgGSepharose 6B. Ih may be the typical intensity over symmetry equivalent reflection. All values in parentheses refer to the highest resolution shell (three to 2.85 . For the higher resolution native information set (Nat1), due to anisotropic diffraction, information have been truncated ellipsoidally inside the 3.0 to two.85 shell. d This is the resolution at which the phasing power fell under 1.0. e RWORK Fobs Fcalc / Fobs, exactly where the summation is over the 35,745 reflections utilised for refinement. f RFREE was calculated using five of data (2179) excluded from refinement (70).PROCHECK (40). Figures had been ready with PyMOL and CHIMERA (41). Residue Bfactors are shown schematically in supplemental Fig. 1. Some domains had limited intramolecular or crystal lattice interactions, top to higher Bfactors (one hundred 00 ). Electron density for the final FIM domain (residues 834 13) was diffuse and fragmented, but rigidbody refinement of a homologybased model lowered the RFREE by 0.38 , supporting its presence at that place. Electron density is absent for interdomain linker residues 24359, 591600, 605619, and 744 755. For illustrative purposes only, these fragments have been constructed as extended coils to show the domain topology. The map revealed seven glycosylation web pages (Nglycosylation of Asn303, Oglycosylation of Thr17 and Thr371, and 1C linked mannosylation (42) of Trp8, Trp11, Trp547, and Trp550). The sugar moieties at Asn303 were built as 1OG1 and 14linked Nacetylglucosamine. Two sugar moieties at Thr17 have been constructed as 1OG1linked fucose and 1linked glucose by analogy with other thrombospondinlike repeat domains (e.g. PDB entry 3GHN). There is absolutely no information about glycosylation at Thr371, but primarily based on the density it was built as OG1 1linked fucose. NGlycosylation is predicted at Asn834 (43, 44), but we could not validate this as a result of the disorder within this region (FIM2). The LR module Ca2 binding web site is occupied by Cd2 , as judged by its 2Fo Fc peak TTA-A2 Biological Activity height and a robust anomalous peak in an anomalous distinction Fourier. The ionic radii of Cd2 and Ca2 are extremely equivalent. Atomic coordinates and structure components for C6 are deposited within the Protein Information Bank with accession quantity 3T5O.Results General Structure of C6The crystal structure of C6 was solved by a mixture of experimental phasing and molecular replacement at three resolution (see “Experimental Procedures,” Table 1, and supplemental Fig. 1). Interpretable electron density exists for all domains except for FIM2 (see beneath) and a few interdomain linkers. The nine auxiliary domains are normally small and rigid, ranging in size from 35 to 75 residues and containing two disulfide bonds. In contrast, the big MACPF domain contains only one particular intradomain disulfide bond. C6 has the general shape of a seahorse, a rather flat molecule using a headtotail distance of 215 (Fig. 1). The MACPF domain (residues 160 01) itself is only 75 tall, along with the further height of C6 is accounted for by auxiliary domains as follows: in unique, four Cterminal domains (complement handle protein (“CCP”) modules and element I modules (“FIMs”) that extend from the upper body of the MACPF core. These auxiliar.