Study on the Room Temperature Phosphorescence of Protein

The phosphorescence analysis method for bovine serum albumin (BSA) and human serum albumin (HSA) was developed based on the protein phosphorescence from tryptophan residues buried within the cores of it.Various affects including atoms,pH condition and the de-oxygenation concentration were discussed The phosphorescence of BSA and HSA was enhanced via the addition of iodide to introduce the so-called heavy atom” effect and the use of sodium sulfite for chemical de-oxygenation.The phosphorescence locates 443nm when it was excited at 287nm,and the phosphorescence has better repetition and stability under the experimental condition.The linearity and detection limit for BSA and HSA were 1×10-6—8.6×10-5mol/L and 2.20×10-7mol/L,3×10-6—13×10-5mol/L and 4.10×10-7mol/L,respectively.The spectra characteristics including the fluorescence/phosphorescence lifetime and the polarization were determined.The results show tryptophan residues fluorescence spectra in BSA have two decay forms,while those in HSA have only one.Their phosphorescence belongs to long-lifetime phosphorescence and the phosphorescence spectra are incompletely polarized.The value of polarization difference between phosphorescence and fluorescence revealed that the microenvironments of the tryptophan residues are different in the two forms of luminescence.