Temperature dependence of solvation dynamics and anisotropy decay in a protein: ANS in bovine serum albumin.
Temperature dependence of solvation dynamics and fluorescence anisotropy decay of 8-anilino-1-naphthalenesulfonate (ANS) bound to a protein, bovine serum albumin (BSA), are studied. Solvation dynamics of ANS bound to BSA displays a component (300 ps) which is independent of temperature in the range of 278-318 K and a long component which decreases from 5800 ps at 278 K to 3600 ps at 318 K. The temperature independent part is ascribed to a dynamic exchange of bound to free water with a low barrier. The temperature variation of the long component of solvation dynamics corresponds to an activation energy of 2.1 kcal mol(-1). The activation energy is ascribed to local segmental motion of the protein along with the associated water molecules and polar residues. The time scale of solvation dynamics is found to be very different from the time scale of anisotropy decay. The anisotropy decays are analyzed in terms of the wobbling motion of the probe (ANS) and the overall tumbling of the protein.
Sahu
Kalyanasis
K
Physical Chemistry Department, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India.
Mondal
Sudip Kumar
SK
Ghosh
Subhadip
S
Roy
Durba
D
Bhattacharyya
Kankan
K
D000817:Anilino Naphthalenesulfonates / Q000737:chemistry*; D000818:Animals; D016880:Anisotropy; D002417:Cattle; D002627:Chemistry, Physical / Q000379:methods*; D019277:Entropy; D008968:Molecular Conformation; D011487:Protein Conformation; D017510:Protein Folding; D012709:Serum Albumin / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013696:Temperature; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
D000817:Anilino Naphthalenesulfonates; D012709:Serum Albumin; D012997:Solvents; D014867:Water; C027132:1-anilino-8-naphthalenesulfonate