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

Eurobic9, 2-6 September, 2008, Wrocław, Poland
P6. Fe-Fe Hydrogenases: Activity Does not Correlate with Oxygen
Sensitivity
C. Baffert a , M. Demuez b , L. Girbal b , I. Meynial-Salles b , P. Soucaille b , F. Leroux a ,
B. Burlat a , P. Bertrand a , B. Guigliarelli a , C. Léger a ,
a
Laboratoire de Bioénergétique et Ingénierie des, Université de Provence/ CNRS, 31 Chemin J. Aiguier, 13402,
Marseille, France
e-mail: carole.baffert@ibsm.cnrs-mrs.fr
b
Laboratoire d'Ingénierie des Systèmes Biologique, INSA-CNRS-INRA, 135, avenue de Rangueil, 31077,
Toulouse, France
Hydrogen metabolism is a field in expansion because of the potential utilisation of micro-organisms in
dihydrogen production. Hydrogenases are the metalloenzymes that catalyse the production and oxidation of H2.
They are classified as Fe-Fe and Ni-Fe according to the structure of their active site [1]. They usually react
quickly with inhibitors such as O2 and CO [2], whereas applications of hydrogenases require that the enzyme
can work in the presence of O2. For this study, we selected the Fe-Fe hydrogenases from the bacterium
Clostridium acetobutylicum (Ca) because it is one of the most active hydrogenases, and because biochemical and
molecular biology procedures are available in our group to engineer and purify this enzyme [3]. To measure its
activity, we use Protein Film Voltammetry, whereby the hydrogenase is immobilized onto an electrode and
electron transfer is direct. The redox state of the enzyme depends on the electrode potential and the measured
current is proportional to the turnover frequency [4.5]. We studied the O2 sensitivity of this enzyme and the
inhibition mechanism. We showed that different inhibition processes coexist and we quantified their kinetics [6].
These results could be compared to there obtained with the Fe-Fe hydrogenase from Desulfovibrio desulfuricans
[2]: despite the fact that the two enzymes have very similar structure, they react with O2 in different manners.
The inhibition of Ca hydrogenase by O2 is surprisingly slow but partly irreversible.
References:
[1] De Lacey A. L., et al., Chem. Rev. 107, (2007), 4304.
[2] Vincent K. A., et al., J. Am. Chem. Soc. 127 (2005) 8179.
[3] Demuez M., et al., FEMS Microbiology Letters 275 (2007)113.
[4] Léger, C., et al., J. Am. Chem. Soc., 126 (2004) 38
[5] Léger, C., Bertrand, P., Chem Rev, in press (july 2008).
[6] Baffert C., et al., Angew. Chem. Int. Ed. 47 (2008) 2052.
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