Developing new fluorophores for applications in protease detection and protein labeling

Abstract

The design and synthesis of a new bi-functional fluorophore with emission and excitation wavelengths similar to fluorescein, and the utility of the fluorophore in microarray and bioimaging applications are described herein. We demonstrate the compatilibity of the fluorophore to solid-phase peptide synthesis for the assembly of various fluorophore-peptide conjugates which are used fluorogenic substrates for detecting protease activity on the microarray and in live cells. With the objective of expanding the bioimaging applications of the fluorophore to detecting protease activity in specific organelles, we synthesized, via solid phase synthesis, peptide conjugates functionalized with an alkyne which can be attached to cellular localization sequences via ¿click chemistry¿. The use of a single fluorophore for these applications obviates the need for re-designing and synthetic evaluation of peptide conjugates for potetntial substrate profiling on the microarray and the live-cell imaging of enzyme activity separately.

Based on the scaffold of our new fluorophore, we designed and synthesized a panel of new fluorophores with emission wavelengths from blue to yellow region by the ¿click¿ reaction of alkyne-functionalized xanthones and xanthenes with various azides. Screening of these fluorophores led to the identification of ¿hit¿ fluorophores which showed a fluorescence increase upon triazole formation. These ¿click¿-activated fluorogenic dyes could potentially be used for bioconjugation and bioimaging purposes.