title: Solvation dynamics and intermittent oscillation of cell membrane: live Chinese hamster ovary cell.
abstract: Dynamics of the exofacial thiols (i.e., cell surface thiol containing membrane proteins) of a live Chinese hamster ovary (CHO) cell is probed by time-resolved confocal microscopy. For this purpose, a fluorescent probe, 7-(diethylamino)-3-(4-maleimidophenyl)-4-methylcoumarin (CPM) is covalently attached to the exofacial thiols. The emission maximum of CPM bound exofacial thiols indicates a highly exposed and polar environment. Using CPM, we studied solvation dynamics, for the first time, at the membrane of a live cell. The thiol containing membrane proteins shows ultraslow response with average solvation time, ⟨τs⟩ = 475 ps. CPM labeled exofacial thiols also show spontaneous, intermittent oscillation in fluorescence intensity with a period of 0.5-1.0 s. This is ascribed to reversible, intermittent changes in the structure and conformation of the membrane proteins.
authors.affiliation: Department of Physical Chemistry, Indian Association for the Cultivation of Science , Jadavpur, Kolkata 700 032, India.
authors.forename: Shirsendu
authors.initials: S
authors.lastname: Ghosh
authors.forename: Shyamtanu
authors.initials: S
authors.lastname: Chattoraj
authors.forename: Kankan
authors.initials: K
authors.lastname: Bhattacharyya
mesh_terms: D000818:Animals; D016466:CHO Cells; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D005456:Fluorescent Dyes / Q000378:metabolism; D018613:Microscopy, Confocal; D015394:Molecular Structure; D013438:Sulfhydryl Compounds / Q000737:chemistry* / Q000378:metabolism
chemical_list: D005456:Fluorescent Dyes; D013438:Sulfhydryl Compounds