CRYSTAL-STRUCTURE OF CYTOCHROME C(3) FROM DESULFOVIBRIO-DESULFURICANSNORWAY AT 1-CENTER-DOT-7 ANGSTROM RESOLUTION

The crystal structure of cytochrome c(3) (M(r) 13,000) from Desulfovib rio desulfuricans (118 residues, four heme groups) has been crystallog raphically refined to 1.7 Angstrom resolution using a simulated anneal ing method, based on the structure-model at 2.5 Angstrom resolution, a lready published. The final R-factor for 10,549 reflections was 0.198 covering the range from 5.5 to 1.7 Angstrom resolution. The individual temperature factors were refined for a total of 1059 protein atoms, t ogether with 126 bound solvent molecules. The structure has been analy zed with respect to its detailed conformational properties, secondary structure features, temperature factor behaviour, bound solvent sites and heme geometry and ligation. The characteristic secondary structure s of the polypeptide chain of this molecule are one extended alpha-hel ix, a short beta-strand and 13 reverse turns. The four heme groups are located in different structural environments, all highly exposed to s olvent. The particular structural features of the heme environments ar e compared to the four hemes of the cytochrome c(3) from Desulfovibrio vulgaris Miyazaki.