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Fluorescent Detection of a Partially Unfolded Conformation of Beta‐Lactoglobulin Using Squaraine Dyes
Author(s) -
Kovalska V.B.,
Losytskyy M.Yu.,
Reis L.V.,
Santos P.F.,
Yarmoluk S.M.
Publication year - 2014
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.201200120
Subject(s) - fluorescence , chemistry , benzothiazole , substituent , photochemistry , globular protein , crystallography , stereochemistry , organic chemistry , physics , quantum mechanics
Summary Six benzothiazole squaraine dyes were studied as fluorescent probes for detection of thermally‐induced conformation changes of amyloidogenic protein beta‐lactoglobulin (BLG). Majority of dyes have shown a strong fluorescent response when complexed with native protein, and at temperature of protein transition to “molten globule” state (65°C) an additional increase of dyes – BLG complex emission intensity up to 4.8 times was observed. The study of step‐by‐step BLG unfolding shows that dyes maximum fluorescence intensity was reached at temperatures around 55–59°C, which can be associated with the affinity of the dyes to tightly packed protein R‐state. Squaraine dye P‐15 containing diethylamino substituent in squaric core and a short N‐ethyl pendent groups displayed the highest sensitivity to temperature induced conformational changes of BLG. This dye is proposed for studies as fluorescent probe for structural changes of globular proteins.