Milardi Danilo, Grasso Domenico M, Verbeet Martin Ph, Canters Gerard W, La Rosa Carmelo
Istituto di Biostrutture e Bioimmagini-CNR, Sezione di Catania, Viale Andrea Doria 6, Italy.
Arch Biochem Biophys. 2003 Jun 1;414(1):121-7. doi: 10.1016/s0003-9861(03)00167-x.
The stabilizing potential of the copper ion and the disulfide bridge in azurin has been explored with the aim of inspecting the ways in which these two factors influence one another. Specifically, whether copper and disulfide contributions to protein stability are additive has been examined. To this aim, the thermal unfolding of a copper-depleted mutant lacking the disulfide bridge between Cys3 and Cys26 (apo C3A/C26A azurin) was studied by differential scanning calorimetry. A comparison of the unfolding parameters of holo and apo C3A/C26A azurin with the apo C3A/C26A protein has shown that the effects of simultaneous copper and disulfide depletion are additive only at two temperatures: T=15 degrees C and T=67 degrees C. Within this range the presence of the copper ion and the disulfide bridge has a positive synergistic effect on azurin stability. These findings might have implications for the rational use of the stabilizing potential of copper and disulfides in copper protein engineering.
为了探究铜离子和天青蛋白中二硫键的稳定潜力是如何相互影响的，对其进行了研究。具体而言，考察了铜和二硫键对蛋白质稳定性的贡献是否具有加和性。为此，通过差示扫描量热法研究了缺乏Cys3和Cys26之间二硫键的铜缺失突变体（脱辅基C3A/C26A天青蛋白）的热解折叠过程。将全蛋白和脱辅基C3A/C26A天青蛋白与脱辅基C3A/C26A蛋白的解折叠参数进行比较，结果表明，只有在两个温度下，即T = 15℃和T = 67℃时，同时去除铜和二硫键的影响才具有加和性。在此温度范围内，铜离子和二硫键的存在对天青蛋白稳定性具有正协同效应。这些发现可能对在铜蛋白工程中合理利用铜和二硫键的稳定潜力具有启示意义。
