title: Ultrafast electron transfer in riboflavin binding protein in macromolecular crowding of nano-sized micelle.
abstract: In this contribution, we have studied the dynamics of electron transfer (ET) of a flavoprotein to the bound cofactor, an important metabolic process, in a model molecular/macromolecular crowding environments. Vitamin B(2) (riboflavin, Rf) and riboflavin binding protein (RBP) are used as model cofactor and flavoprotein, respectively. An anionic surfactant sodium dodecyl sulfate (SDS) is considered to be model crowding agent. A systematic study on the ET dynamics in various SDS concentration, ranging from below critical micellar concentration (CMC), where the surfactants remain as monomeric form to above CMC, where the surfactants self-assemble to form nanoscopic micelle, explores the dynamics of ET in the model molecular and macromolecular crowding environments. With energy selective excitation in picosecond-resolved studies, we have followed temporal quenching of the tryptophan residue of the protein and Rf in the RBP-Rf complex in various degrees of molecular/macromolecular crowding. The structural integrity of the protein (secondary and tertiary structures) and the vitamin binding capacity of RBP have been investigated using various techniques including UV-Vis, circular dichroism (CD) spectroscopy and dynamic light scattering (DLS) studies in the crowding environments. Our finding suggests that the effect of molecular/macromolecular crowding could have major implication in the intra-protein ET dynamics in cellular environments.
authors.affiliation: Department of Chemical, Biological and Macromolecular Sciences, SN Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098, India.
authors.forename: Surajit
authors.initials: S
authors.lastname: Rakshit
authors.forename: Ranajay
authors.initials: R
authors.lastname: Saha
authors.forename: Pramod Kumar
authors.initials: PK
authors.lastname: Verma
authors.forename: Rajib Kumar
authors.initials: RK
authors.lastname: Mitra
authors.forename: Samir Kumar
authors.initials: SK
authors.lastname: Pal
mesh_terms: D000465:Algorithms; D002942:Circular Dichroism; D004579:Electron Transport; D007700:Kinetics; D008027:Light; D046911:Macromolecular Substances / Q000737:chemistry* / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism; D008823:Micelles; D008958:Models, Molecular; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012256:Riboflavin / Q000737:chemistry / Q000378:metabolism; D012542:Scattering, Radiation; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013501:Surface-Active Agents / Q000737:chemistry / Q000378:metabolism; D014364:Tryptophan / Q000737:chemistry / Q000378:metabolism
chemical_list: D046911:Macromolecular Substances; D026901:Membrane Transport Proteins; D008823:Micelles; D013501:Surface-Active Agents; C019079:riboflavin-binding protein; D012967:Sodium Dodecyl Sulfate; D014364:Tryptophan; D012256:Riboflavin