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Publication Abstract from PubMed

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 charge 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 retinylidine 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.

Rational Design of a Colorimetric pH Sensor from a Soluble Retinoic Acid Chaperone.,Berbasova T, Nosrati M, Vasileiou C, Wang W, Lee KS, Yapici I, Geiger JH, Borhan B J Am Chem Soc. 2013 Sep 20. PMID:24059243^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.