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Journal of Thermal Analysis and Calorimetry

, Volume 98, Issue 3, pp 877–883 | Cite as

Reversible unfolding of poplar iso-plastocyanins

  • V. I. Getov
  • G. R. Toromanov
  • G. K. Kostov
  • M. I. Dimitrov
  • A. Ch. Shosheva
Article

Abstract

We attempted to determine the experimental conditions under which poplar plastocyanin iso-forms PCa and PCb undergo reversible thermal unfolding studied by differential scanning calorimetry (DSC). Our results indicate that an exothermic unfolding process exists always in the presence of molecular oxygen. Reversible unfolding and almost perfect two-state transitions were exhibited in the presence of TCEP under anaerobic conditions. This suggests that the second endothermic peak is due to copper-site disulfide dimmers formed during thermal denaturation. The conformational thermal stability of reduced PCbG (25 °C) = 33.9 kJ mol−1) has proven to be higher than that of reduced PCaG(25 °C) = 22.9 kJ mol−1).

Keywords

Plastocyanin Iso-forms Differential scanning calorimetry Thermal stability 

Notes

Acknowledgements

This work was supported by grants of Fund “Scientific researches” of the Bulgarian Ministry of Education and Sciences (contract No. MY-Б-1511/2005 and No. Б-1519/05/2005).

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Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2009

Authors and Affiliations

  • V. I. Getov
    • 1
  • G. R. Toromanov
    • 1
  • G. K. Kostov
    • 1
  • M. I. Dimitrov
    • 1
  • A. Ch. Shosheva
    • 1
  1. 1.Bulgarian Academy of SciencesInstitute of BiophysicsSofiaBulgaria

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