I am doing fluorescence experiment of protein solution, but the problem is that the same solution gives different maximum emission value a day after the previous one.
Is it possible that the protein undergo some sort of denaturation/structural or conformational change during the course of time? As you know tryptophan emission is quite sensitive to local environment a change in local environment by any process could lead to spectral changes.
(Please give more information when you request a suggestion so that a specific answer may be provided. What is your fluorophore, how much is the change is spectra (show the spectra), how many times you have repeated the experiment, etc)
I am using HSA solution in phosphate buffer of 7.4 pH. Day 1 it gives a maximum emission of 103 (a.u) at 343 nm and on third day it gives maximum emission of 114 (a.u) at 343 nm. I am just curious if that is possible or there is some kind of error in the experiment.