This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.106.099531v1 92/6/2131    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Strambini, G. B. Articles by Gonnelli, M. Search for Related Content PubMed PubMed Citation Articles by Strambini, G. B. Articles by Gonnelli, M.

Protein Stability in Ice

Consiglio Nazionale delle Ricerche, Istituto di Biofisica, Pisa, Italy

Correspondence: Address reprint requests to Giovanni B. Strambini, CNR-Istituto di Biofisica Area della Ricerca via Moruzzi, 1 56124 Pisa, Italy. Tel.: 39-050-315-3046; Fax: 39-050-315-2760; E-mail: giovanni.strambini{at}pi.ibf.cnr.it.

This study presents an experimental approach, based on the change of Trp fluorescence between native and denatured states of proteins, which permits to monitor unfolding equilibria and the thermodynamic stability (G°) of these macromolecules in frozen aqueous solutions. The results obtained by guanidinium chloride denaturation of the azurin mutant C112S from Pseudomonas aeruginosa, in the temperature range from –8 to –16°C, demonstrate that the stability of the native fold may be significantly perturbed in ice depending mainly on the size of the liquid water pool (V_L) in equilibrium with the solid phase. The data establish a threshold, around V_L = 1.5%, below which in ice G° decreases progressively relative to liquid state, up to 3 kcal/mole for V_L = 0.285%. The sharp dependence of G° on V_L is consistent with a mechanism based on adsorption of the protein to the ice surface. The reduction in G° is accompanied by a corresponding decrease in m-value indicating that protein-ice interactions increase the solvent accessible surface area of the native fold or reduce that of the denatured state, or both. The method opens the possibility for examining in a more quantitative fashion the influence of various experimental conditions on the ice perturbation and in particular to test the effectiveness of numerous additives used in formulations to preserve labile pharmaco proteins.

This article has been cited by other articles:

				E. Gabellieri, E. Balestreri, A. Galli, and P. Cioni Cavity-Creating Mutations in Pseudomonas aeruginosa Azurin: Effects on Protein Dynamics and Stability Biophys. J., July 15, 2008; 95(2): 771 - 781. [Abstract] [Full Text] [PDF]

				V. Ragoonanan and A. Aksan Heterogeneity in Desiccated Solutions: Implications for Biostabilization Biophys. J., March 15, 2008; 94(6): 2212 - 2227. [Abstract] [Full Text] [PDF]