ISBN: 978-83-60043-10-3 - eurobic9

Eurobic9, 2-6 September, 2008, Wrocław, Poland
P26. Cobalt-porphyrin Containing γ Subunit of Desulfoviridin of D.gigas
S.A. Bursakov a , A. V. Kladova a , O. Yu. Gavel a , J. Calvete b , V. Cabral a , I. Moura a , J.J.G.
Moura a
a REQUIMTE, Departamento de Química, Centro de Química Fina e Biotecnologia, Faculdade de Ciências e
Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
e-mail: sergey@dq.fct.unl.pt
b Instituto de Investigaciones Biomédicas, C.S.I.C., Valencia, Spain
A cobalt- porphyrin containing protein (CoPf) was isolated from the sulphate-reducing bacteria Desulfovibrio
gigas [1, 2]. The monomeric violet coloured protein contains one molecule of cobalt per molecule of protein in a
non covalently bound Co (III) porphyrin-like cofactor and exhibits UV-visible spectrum with peaks at 279 nm,
420 nm and 590 nm with shoulders at 300 nm, 395 nm and 550 nm.
CoPf was cloned and overexpressed in E. coli cells. The apo-form consist of 105 amino acids residues with
molecular weight around 11.9 kDa. CoPf contains only few aromatic amino acid residues that are responsible for
low extinction coefficient at 280 nm. Thus, the pure protein has the ratio A590/280 and the ratio A420/A280 is
around 1.48 and 3.22, respectively. Alignment of the CoPf with proteins from the database BLAST show very
high homology from 72 to 82% of this protein with gamma subunit of dissimilatory sulfite reductase from
Desulfovibrio vulgaris (Hildenborough), Desulfovibrio desulfuricans G20, Thermodesulforhabdus norvegica and
Desulfotalea psychrophila. According to the results of mass spectrometry and modification by iodoacetamide
(IA) and vinylpyridine (VP), CoPf has two cysteines linked by one bridge and one of them only accessible to IA
and VP, in presence denaturing agent (5 M ClGu). As isolated the protein is EPR silent, suggesting the presence
of diamagnetic Co 3+ not easly reduced by sodium dithionite.
Acknowledgement: POCI/QUI/59119/2004 (FCT), No E-62/06 (CRUP), SFRH/BPD/28380/2006 and
SFRH/BD/24744/2005.
References:
[1] J.J.G. Moura, I. Moura, M. Bruschi, J. Le Gall and A. V. Xavier, Biochem Biophys Res Commun. 92, 962
(1980).
[2] E.C. Hatchikian, Biochem Biophys Res Commun. 103, 521 (1981).
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