Exploring hydrophobic subdomain IIA of the protein bovine serum albumin in the native, intermediate, unfolded, and refolded states by a small fluorescence molecular reporter.
A simple intramolecular charge transfer (ICT) compound, 5-(4-dimethylamino-phenyl)-penta-2,4-dienoic acid methyl ester (DPDAME), has been documented to be a potential molecular reporter for probing microheterogeneous environments of a model transport protein bovine serum albumin (BSA) using spectroscopic techniques. Meteoric modifications to the emission profile of DPDAME upon addition of BSA come out to be a result of its binding to hydrophobic subdomain IIA. The highly polarity-sensitive ICT emission of DPDAME is found to be a proficient extrinsic molecular reporter for efficient mapping of native, intermediate, unfolded, and refolded states of the protein. Experimental data coupled with a reinforcing support from theoretical simulation using CHARMM22 software confirm the binding site of the probe to be the subdomain IIA of BSA, while FRET study reveals a remarkably close approach of our extrinsic molecular reporter to Trp-212 (in domain IIA): the distance between DPDAME and Trp-212 is 1.437 nm. The caliber of DPDAME as an external fluorescence marker also extends to the depiction of protein-surfactant (BSA-SDS) interaction to commendable fruition. Additionally, the protective action of small amounts of SDS on urea-denatured protein is documented by polarity-sensitive ICT emission of the probe. The present study also reflects the enhancement of the stability of BSA with respect to chemically induced denaturation by urea as a result of binding to the probe DPDAME.
Paul
Bijan Kumar
BK
Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Calcutta 700009, India.
Samanta
Anuva
A
Guchhait
Nikhil
N
D000818:Animals; D002417:Cattle; D031541:Fluorescence Resonance Energy Transfer; D005456:Fluorescent Dyes / Q000737:chemistry* / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D008744:Methylamines / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D010421:Pentanoic Acids / Q000737:chemistry*; D011485:Protein Binding; D017510:Protein Folding; D012710:Serum Albumin, Bovine / Q000737:chemistry* / Q000378:metabolism; D013501:Surface-Active Agents / Q000737:chemistry
C551375:5-(4-dimethylamino-phenyl)-penta-2,4-dienoic acid methyl ester; D005456:Fluorescent Dyes; D008744:Methylamines; D010421:Pentanoic Acids; D013501:Surface-Active Agents; D012710:Serum Albumin, Bovine