Conformational partitioning in pH-induced fluorescence of the kindling fluorescent protein (KFP).

Kindling fluorescent protein (KFP) is considered as a prospective fluorophore for high-resolution nanoscopy. Analysis of pH dependence of the absorption and fluorescence spectra of KFP in aqueous solutions prompted us to assume that a shift in conformational equilibrium is responsible for substantial enhancement of red fluorescence in KFP at alkaline pH. Variations in pH also resulted in noticeable shifts in band maxima for absorption, fluorescence excitation, and fluorescence emission.