Spectroscopic and thermodynamic properties of recombinant heat shock protein A6 from Camelus dromedarius
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Heat shock protein A6, also known as HSP70B’, is a member of the Hsp70 family of molecular chaperones. Under stressed conditions, the level of HSPA6 increases substantially, and the protein has been targeted as a biomarker of cellular stress in several studies. We report the spectroscopic and thermodynamic properties of Arabian camel species cHSPA6, determined by measurement of intrinsic and extrinsic fluorescence emission, and use of far-UV circular dichroism and dynamic multimode spectroscopy. Our results showed that cHSPA6 has similar binding affinity for both ATP and ADP (K D = ~50 nM). Binding of ATP and ADP reduced the surface hydrophobicity of the protein, and slightly altered its secondary structure, suggesting localized conformational rearrangement after ATP or ADP binding. Dynamic multimode spectroscopy revealed that cHSPA6 unfolds through three transitions with melting points (T m) of 42.3 ± 0.2, 61.3 ± 0.1, and 81.2 ± 0.2 °C. To the best of the author’s knowledge, and literature search, this is the first report of the spectroscopic and thermodynamic properties of the Arabian camel heat shock protein.
KeywordsRecombinant protein Heat shock protein Protein stability Folding Fluorescence quenching Dynamic multimode spectroscopy
Fast protein liquid chromatography
Double strength Luria–Bertani
Molecular weight cut off
Nucleotide binding domain
Optical density at 600 nm
Rotation per minute
Substrate binding domain
The authors extend their appreciation to King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia, for funding this work through project # A-C-11-0606.
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