Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States.
J Am Chem Soc. 2013 Oct 30;135(43):16111-9. doi: 10.1021/ja404900k. Epub 2013 Oct 18.
Reengineering of cellular retinoic acid binding protein II (CRABPII) to be capable of binding retinal as a protonated Schiff base is described. Through rational alterations of the binding pocket, electrostatic perturbations of the embedded retinylidene chromophore that favor delocalization of the iminium charge lead to exquisite control in the regulation of chromophoric absorption properties, spanning the visible spectrum (474-640 nm). The pKa of the retinylidene protonated Schiff base was modulated from 2.4 to 8.1, giving rise to a set of proteins of varying colors and pH sensitivities. These proteins were used to demonstrate a concentration-independent, ratiometric pH sensor.
描述了细胞视黄酸结合蛋白 II（CRABPII）的重构，使其能够与质子化的席夫碱结合视网膜。通过对结合口袋进行合理的改变，对嵌入的视黄醛发色团进行静电微扰，有利于亚胺电荷的离域，从而对发色团吸收特性进行精细调控，覆盖可见光谱（474-640nm）。视黄醛质子化席夫碱的 pKa 从 2.4 调节到 8.1，产生了一系列具有不同颜色和 pH 敏感性的蛋白质。这些蛋白质被用于证明一种浓度无关的、比率型的 pH 传感器。
