PRELIMINARY CRYSTALLOGRAPHIC ANALYSIS AND FURTHER CHARACTERIZATION OFA DODECAHEME CYTOCHROME-C FROM DESULFOVIBRIO-DESULFURICANS ATCC-27774

Citation
Av. Coelho et al., PRELIMINARY CRYSTALLOGRAPHIC ANALYSIS AND FURTHER CHARACTERIZATION OFA DODECAHEME CYTOCHROME-C FROM DESULFOVIBRIO-DESULFURICANS ATCC-27774, Acta crystallographica. Section D, Biological crystallography, 52, 1996, pp. 1202-1208
Citations number
34
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Crystallography,"Biochemical Research Methods",Biology
ISSN journal
0907-4449
Volume
52
Year of publication
1996
Part
6
Pages
1202 - 1208
Database
ISI
SICI code
0907-4449(1996)52:<1202:PCAAFC>2.0.ZU;2-6
Abstract
Dodecaheme cytochrome c has been purified from Desulfovibrio (D.) desu lfuricans ATCC 27774 cells grown under both nitrate and sulfate-respir ing conditions. Therefore, it is likely to play a role in the electron -transfer system of both respiratory chains. Its molecular mass (37 76 8 kDa) was determined by electrospray mass spectrometry. Its first 39 amino acids were sequenced and a motif was found between amino acids 3 2 and 37 that seems to exist in all the cytochromes of the c3 type fro m sulfate-reducing bacteria sequenced at present. The midpoint redox p otentials of this cytochrome were estimated to be -68, -120, -248 and -310 mV. Electron paramagnetic resonance spectroscopy of the oxidized cytochrome shows several low-spin components with a g(max) spreading f rom 3.254 to 2.983. Two crystalline forms were obtained by vapour diff usion from a solution containing 2% PEG 6000 and 0.25-0.75 M acetate b uffer pH = 5.5. Both crystals belong to monoclinic space groups: one i s PZ,, with a = 61.00, b = 106.191 c = 82.05 Angstrom, beta = 103.61 d egrees, and the other is C2 with a = 152.17. b = 98.45, c = 89.24 Angs trom, beta = 119.18 degrees. Density measurements of the P2(1) crystal s suggest that there are two independent molecules in the asymmetric u nit. Self-rotation function calculations indicate, in both crystal for ms, the presence of a non-crystallographic axis perpendicular to the c rystallographic twofold axis. This result and the calculated values fo r the volume per unit molecular weight of the C2 crystals suggest the presence of two or four molecules in the asymmetric unit.