Programmed cell death-1 (PD-1) is a coinhibitory receptor that suppresses T activation and an important cancer immunotherapy target. Upon by its ligand PD-L1, PD-1 thought to suppress signaling through the (TCR). By titrating in biochemical reconstitution system, we demonstrate co-receptor CD28 strongly preferred over TCR as target for dephosphorylation PD-1-recruited Shp2 phosphatase. We also show CD28, but not TCR, preferentially dephosphorylated response PD-L1 intact system. These results...

The effect of a room temperature ionic liquid (RTIL) on the conformational dynamics protein, human serum albumin (HSA), is studied by fluorescence correlation spectroscopy (FCS). For this, protein was covalently labeled fluorophore, 7-dimethylamino-3-(4-maleimidophenyl)-4-methylcoumarin (CPM). On addition RTIL ([pmim][Br]) to native diffusion coefficient (D(t)) decreases and hydrodynamic radius (R(h)) increases. This suggests that acts as denaturant when in state. However, [pmim][Br]...

Diffusion of organic dyes in neat room temperature ionic liquid (RTIL) and RTIL-mixed micelle has been studied by fluorescence correlation spectroscopy (FCS). We have selected two RTILs, 3-pentyl-1-methyl imidazolium bromide ([C5C1Im][Br]) the corresponding tetra-fluoroborate ([C5C1Im][BF(4)]). coefficients (D(t)) three dyes--DCM (neutral), C480 C343 (anionic)--in these RTILs are ∼100 times slower compared to water. This indicates very high viscosity RTILs. In contrast water, D(t) RTIL...

The interaction between the plasma protein bovine serum albumin (BSA) and drug ibuprofen (IBU) has been investigated at three different pH values (7.4, 6.5, 8.0) in presence of oligosaccharides surfactants. analysis BSA with surfactants also studied absence ibuprofen. results obtained give convenient efficient access to understand mechanism binding BSA, major forces involved are found be hydrophobic forces, hydrogen bonding ionic interactions. In addition that, formation inclusion complexes...

Fluorescence resonance energy transfer (FRET) from coumarin 480 (C480) to rhodamine 6G (R6G) is studied in a room temperature ionic liquid (RTIL) microemulsion by picosecond and femtosecond emission spectroscopy. The comprised of the RTIL 1-pentyl-3-methylimidazolium tetraflouroborate, [pmim][BF4], TX-100/ benzene. We have with without water. time constants FRET were obtained risetime acceptor emission. In microemulsion, occurs on multiple scales: 1, 250, 3900 ps. water containing rise...

Time-resolved confocal microscopy has been applied to study the cytoplasm and nucleus region of a single live Chinese hamster ovary (CHO) cell. To select region, two different fluorescent probes are used. A hydrophobic dye, DCM, localizes preferentially in CHO DNA binding DAPI, is found be inside The locations clearly seen image. Emission maxima dyes (DCM DAPI nucleus) compared those same solvents. From this, it concluded that polarity (dielectric constant, ε) microenvironment DCM ~15. much...

Abstract Programmed death-1 (PD-1) is a co-inhibitory receptor that suppresses T cell activation and an important cancer immunotherapy target. Upon by its ligand PD-L1, PD-1 thought to suppress signaling through the (TCR). Here, titrating strength of in both biochemical reconstitution systems cells, we demonstrate coreceptor CD28 strongly preferred over TCR as target for dephosphorylation PD-1- recruited Shp2 phosphatase. We also show colocalizes with costimulatory plasma membrane...

Carbon quantum dots (CQD) are a novel class of nanomaterials that has significant importance for applications in bioimaging, drug loading and delivery. Their easy preparation, tunable optoelectronic property, low toxicity, excellent biocompatibility, superior photostability, exceptional water solubility contribute to their tremendous potentials various applications. In this study, we synthesized carbon using greener cost-efficient top-down reflux methods, characterized the CQDs by...

Abstract Total internal reflection fluorescence (TIRF) microscopy enables observation of complex bio-assemblies and macromolecular dynamics in high spatial-temporal resolution at single-molecule level real-time. With TIRF illumination, fluorophores near a sample substrate are excited by an evanescent field, thereby circumventing the axial diffraction limit light. Prism-based (p-TIRF) microscopes comparatively easy to use. They may be readily adjusted meet requirements broad range...

Conformational dynamics plays a critical role in the activation, deactivation, and open–close activities of ion channels living cells. Such conformational is often inhomogeneous extremely difficult to be directly characterized by ensemble-averaged spectroscopic imaging or only single channel patch-clamp electric recording methods. We have developed new combined technical approach, single-molecule FRET microscopy, probe cell simultaneous correlated measurements real-time with single-channel...

Abstract A major unanswered question is how a TCR discriminates between foreign and self-peptides presented on the APC surface. Here, we used in situ fluorescence resonance energy transfer (FRET) to measure distances of single TCR–pMHC bonds conformations individual TCR–CD3ζ receptors at membranes live primary T cells. We found that closely related peptides by forming with different conformations, most potent pMHC forms shortest bond. The bond conformation an intrinsic property independent...

Excited state proton transfer (ESPT) of pyranine (8-hydroxypyranine-1,3,6-trisulfonate, HPTS) in room temperature ionic liquid (RTIL) mixed micelles is studied by femtosecond up-conversion. The micelle consists a triblock copolymer, (PEO)20−(PPO)70−(PEO)20 (Pluronic P123), and one the two RTILs, 1-pentyl-3-methyl-imidazolium bromide ([pmim][Br]) tetra-fluoroborate ([pmim][BF4]). size structure vary with relative amount RTIL. For [pmim][Br], hydrodynamic diameter 26 nm 0.3 M RTIL 3500 3.0...

Dynamic light scattering studies indicate that addition of a room temperature ionic liquid (RTIL, [pmim][Br]), to triblock copolymer (P123) micelle leads the formation giant P123-RTIL clusters size (diameter) 40 nm in 0.9 M and 3500 (3.5 microm) 3 RTIL. They are much larger than P123 ( approximately 18 nm) or [pmim][Br] (1.3 nm). Dynamics different regions aggregate is probed by variation excitation wavelength (lambda(ex)) using femtosecond up-conversion. For lambda(ex) = 375 nm, nonpolar...

The deuterium isotope effect on the solvation dynamics and anisotropy decay of coumarin 480 (C480) in a room temperature ionic liquid (RTIL) microemulsion is studied by femtosecond up-conversion. consists RTIL 1-pentyl-3-methyl-imidazolium tetra-fluoroborate ([pmim][BF(4)]) triton X-100 (TX-100)/benzene. Replacement H(2)O D(2)O causes retardation dynamics. average time C480 (tau(s)) with 5 wt % approximately 1.5-1.7 times slower compared to that containing microemulsion. This suggests main...

Peptides synthesized in the likeness of their native interaction domain(s) are natural choices to target protein–protein interactions (PPIs) due fidelity orthostatic contact points between binding partners. Despite therapeutic promise, intracellular delivery biofunctional peptides at concentrations necessary for efficacy remains a formidable challenge. Peptide amphiphiles (PAs) provide facile method and stabilization bioactive peptides. PAs consisting peptide headgroups linked hydrophobic...

N-methyl-d-aspartate (NMDA) receptor ion channel is activated by the binding of two pairs glycine and glutamate along with application action potential. Binding unbinding ligands changes its conformation that plays a critical role in open–close activities NMDA receptor. Conformation states their dynamics due to ligand are extremely difficult characterize either conventional ensemble experiments or single-channel electrophysiology method. Here we report development new correlated technical...

Understanding the binding details of a small-molecule drug to protein in its partially unfolded state is important for delivery as it provides insight into overall drug-binding ability protein, even when majority pockets are impaired. The interaction proteins with drugs remains poorly understood due lack structural information on their states. Here, we studied between serum albumin (bovine (BSA) model system), an abundant blood that effective carrier numerous known drugs, and nonsteroidal...

Abstract Active enzymes during catalyzing chemical reactions, have been found to generate significant mechanical fluctuations, which can influence the dynamics of their surroundings. These phenomena open new avenues for controlling mass transport in complex and dynamically inhomogeneous environments through localized reactions. To explore this potential, we studied uptake transferrin molecules retinal pigment epithelium (RPE) cells via clathrin-mediated endocytosis. In presence enzyme...

Deuterium isotope effect on the solvation dynamics and fluorescence anisotropy decay of coumarin 153 (C153) bound to dimethyl β-cyclodextrin (DMB) trimethyl (TMB) is studied using femtosecond upconversion. In D2O, there a marked increase in steady state emission quantum yield lifetime C153 DMB TMB. This suggests strong coupling between D2O inside cyclodextrin cavity. average time about 1.7 times slower compared that water. For TMB 1.5 slower. The deuterium at long arises mainly from longer...

Ultrafast fluorescence resonance energy transfer (FRET) in a catanionic [sodium dodecyl sulfate (SDS)-dodecyltrimethyl ammonium bromide (DTAB)] vesicle is studied by femtosecond up-conversion. The vesicles (diameter ∼400 nm for SDS-rich and ∼250 DTAB-rich vesicles) are much larger than the SDS DTAB micelles ∼4 nm). In both micelle vesicles, FRET occurs multiple time scales of correspond to donor-acceptor distance varying between 12 36 Å.

The structure and dynamics of a catanionic vesicle are studied by means femtosecond up-conversion dynamic light scattering (DLS). is composed dodecyl-trimethyl-ammonium bromide (DTAB) sodium dodecyl sulphate (SDS). DLS data suggest that 90 % the vesicles have diameter about 400 nm, whereas other 10 50 nm. in compared with those pure SDS DTAB micelles. We also study different regions micelle/vesicle varying excitation wavelength (lambda(ex)) from 375 to 435 found be more heterogeneous than or...

Understanding the interaction between drug:carrier complex and protein is essential for development of a new drug-delivery system. However, majority reports are based on an understanding interactions drug protein. Here, we present our findings anti-inflammatory diflunisal with carrier cyclodextrin (CD) lysozyme, utilizing steady-state time-resolved fluorescence spectroscopy. Our reveal different pattern molecular inclusion β-CD (β-CD) or hydroxypropyl-β-CD (HP-β-CD) (as host) guest) in...

Clinical trials on the therapeutic effect of curcumin have proven to be highly effective against many diseases including cancer and Alzheimer's. However, molecular mechanism interaction with protein live cell membrane is poorly understood. Here, we report bovine serum albumin (BSA) E. coli in presence organized assemblies sodium dodecyl sulfate (SDS) cetrimonium bromide (CTAB) by fluorescence spectroscopy, laser-scanning confocal microscopy, computation. Enhanced binding constant,...