Novel proton transfer fluorescence probe 2-hydroxy-pyridine and 5-(4-fluorophenyl)-2-hydroxypyridine for studying native, denatured and renatured state of protein Bovine Serum Albumin.

The binding interactions of protein Bovine Serum Albumin (BSA) in its folding, unfolding and refolding states with proton transfer fluorescence probe 2-hydroxy-pyridine (2HP) and 5-(4-fluorophenyl)-2-hydroxypyridine (FP2HP) have been studied using steady state and time-resolved spectroscopy. The higher degree of spectral overlap between donor fluorescence and acceptor absorption is responsible for energy transfer from donor tryptophan to the acceptor probe and has shown remarkable sensitivity of these fluorophore for mapping the protein environment. During denaturation of BSA by guanidine hydrochloride, it shows two peaks of Trp-212 and Tyr-263. Reduction of fluorescence intensity of two peaks upon binding to the probes indicates that these probes not only bind with Trp-212 but also with Tyr-263. The steady state results are also confirmed by time-resolved studies.