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Combining time‐resolved fluorescence with synchronous fluorescence spectroscopy to study bovine serum albumin‐curcumin complex during unfolding and refolding processes
Author(s) -
Barakat Christelle,
Patra Digambara
Publication year - 2012
Publication title -
luminescence
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.428
H-Index - 45
eISSN - 1522-7243
pISSN - 1522-7235
DOI - 10.1002/bio.2354
Subject(s) - chemistry , fluorescence , bovine serum albumin , curcumin , quenching (fluorescence) , fluorescence spectroscopy , tryptophan , denaturation (fissile materials) , photochemistry , urea , analytical chemistry (journal) , chromatography , nuclear chemistry , organic chemistry , biochemistry , amino acid , physics , quantum mechanics
We investigated the complex interaction between bovine serum albumin (BSA) and curcumin by combining time‐resolved fluorescence and synchronous fluorescence spectroscopy. The interaction was significant and sensitive to fluorescence lifetime and synchronous fluorescence characteristics. Binding of curcumin significantly shortened the fluorescence lifetime of BSA with a bi‐molecular quenching rate constant of k q = 3.17 × 10 12 M ‐1 s ‐1 . Denaturation by urea unfolded the protein molecule by quenching the fluorescence lifetime of BSA. The tyrosine synchronous fluorescence spectra were blue shifted whereas the position of tryptophan synchronous fluorescence spectra was red shifted during the unfolding process. However, denaturation of urea had little effect on the synchronous fluorescence peak of tyrosine in curcumin‐BSA complex except in the low concentration range; however, it shifted the peak to the red, indicating that curcumin shifted tryptophan moiety to a more polar environment in the unfolded state. Decreases in the time‐resolved fluorescence lifetime and curcumin‐BSA complex during unfolding were recovered during refolding of BSA by a dilution process, suggesting partial reversibility of the unfolding process for both BSA and curcumin‐BSA complex. Copyright © 2012 John Wiley & Sons, Ltd.