Hall W Paige, Anker Jeffrey N, Lin Yao, Modica Justin, Mrksich Milan, Van Duyne Richard P
Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA.
J Am Chem Soc. 2008 May 7;130(18):5836-7. doi: 10.1021/ja7109037. Epub 2008 Apr 11.
A plasmonic switch based on the calcium-induced conformational changes of calmodulin is shown to exhibit reversible wavelength modulations in response to changing calcium concentration. The extinction maximum (lambdamax) of a localized surface plasmon resonance (LSPR) sensor functionalized with a novel calmodulin construct, cutinase-calmodulin-cutinase (CutCaMCut), reversibly shifts by 2-3 nm. A high-resolution (HR) LSPR spectrometer with a wavelength resolution (3sigma) of 1.5 x 10-2 nm was developed to detect these wavelength modulations in real-time, providing information about the dynamics and structure of the protein. The rate of conversion from open (Ca2+-bound) to closed (Ca2+-free) calmodulin is shown to be 4-fold faster than the reverse process, with a closing rate of 0.127 s-1 and opening rate of 0.034 s-1. As far as we are aware, this plasmonic switch marks the first use of LSPR spectroscopy to detect reversible conformational changes in an unlabeled protein.
一种基于钙调蛋白钙诱导构象变化的等离子体开关,被证明可响应钙浓度变化呈现可逆的波长调制。用新型钙调蛋白构建体角质酶-钙调蛋白-角质酶(CutCaMCut)功能化的局域表面等离子体共振(LSPR)传感器的最大消光波长(λmax)可逆地移动2 - 3纳米。开发了一种波长分辨率(3σ)为1.5×10⁻²纳米的高分辨率(HR)LSPR光谱仪,用于实时检测这些波长调制,从而提供有关蛋白质动力学和结构的信息。从开放(结合Ca²⁺)到关闭(无Ca²⁺)钙调蛋白的转换速率比反向过程快4倍,关闭速率为0.127 s⁻¹,开放速率为0.034 s⁻¹。据我们所知,这种等离子体开关标志着首次使用LSPR光谱法检测未标记蛋白质中的可逆构象变化。