M. Czjzek et al., CRYSTAL-STRUCTURE OF CYTOCHROME C(3) FROM DESULFOVIBRIO-DESULFURICANSNORWAY AT 1-CENTER-DOT-7 ANGSTROM RESOLUTION, Journal of Molecular Biology, 243(4), 1994, pp. 653-667
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.