PRELIMINARY RESULTS FROM CRYSTALLIZATION OF CYTOCHROMES FROM PHOTOSYNTHETIC BACTERIA THIOCAPSA ROSEOPERSICINA

 

Ivana Tomčová1 and Ivana Kutá Smatanová1,2

 

1Institute of Physical Biology, University of South Bohemia České Budějovice,

Zámek 136, 373 33 Nové Hrady, Czech Republic

2Institute of Landscape Ecology, Academy of Science of the Czech Republic, Zámek 136,

373 33 Nové Hrady, Czech Republic

 

 

Cytochromes belong to the family of colored proteins that play an important role in live cells. They incorporate prosthetic group - molecule of heme - that facilitates as a member in process of electron transport. Due to this important function, it is of essential interest to study structural features of cytochromes with modern X-ray crystallographic methods.

Cytochrome c (cyt c) is a low-mass protein (26 kDa) transporting electrons among cytochrome b-c1 complex and complex of cytochromoxidase. Cyt c from the purple photosynthetic bacterium Thiocapsa roseopersicina was isolated and purified according to Bagyinka [1]. The bacterium incorporates four different hydrogenases and three different cytochromes.

Cyt c was crystallized using standard crystallization methods based on vapor diffusion. Crystallization trials were performed in hanging and sitting drops [2-3] at room temperature.   The most suitable concentration of protein (10mg/ml) and the precipitation agent (50% ammonium sulfate) were found. Ranging pH value higher than 7.5 the phase separation of protein was appeared. First crystal growth was observed at pH 6.0.

Particular crystallographic conditions are now being to be optimized in order to prepare monocrystals of cyt c suitable for X-ray diffraction measurement.

 

[1] Bagyinka, C.: unpublished data

[2] Bergfors T. M. (Eds.): Protein Crystallization. Techniques, Strategies and Tips. A Laboratory Manual, International University Line, La Jolla, USA (1999)

[3]  Ducruix A., Giegé R. (Eds.): Crystallization of Nucleic Acids and Proteins. A Practical Approach, Oxford University Press, Oxford  (1999)