30156310
Domain specific association of small fluorescent probe trans-3-(4-monomethylaminophenyl)-acrylonitrile (MMAPA) with bovine serum albumin (BSA) and its dissociation from protein binding sites by Ag nanoparticles: spectroscopic and molecular docking study.
Photoinduced intramolecular charge transfer produced a polar excited state in trans-3-(4-monomethylaminophenyl)acrylonitrile (MMAPA), rendering the resulting emission sensitive to the medium polarity. Strong binding interaction of silver nanoparticles with the probe was observed, causing fluorescence quenching through the static quenching process. The probe MMAPA was found to bind to the less polar hydrophobic, restricted proteinous environment of bovine serum albumin (BSA) resulting in the blue shift of the emission maximum with an increase in emission intensity and fluorescence anisotropy. Studies using site markers of flufenamic acid and phenylbutazone coupled with molecular docking results predicted that the binding site of the probe is in between subdomains IIIA and IB of BSA and is different from the conventional Sudlow sites. The denaturation of the probe-bound BSA by urea or heat released the probe from this proteinous environment to water marked by exactly reverse spectral changes. On the interaction of silver nanoparticles with the probe bound protein, the probe was observed to move from its binding site in the protein to the Ag(0) nanoparticle surface involving conformational changes of the protein near the probe binding site.
12098655
Fluorescent probing of urea-induced chemical unfolding of bovine serum albumin by intramolecular charge transfer fluorescence probe E-3-(4-dimethylamino-naphthalen-1-yl)-acrylic acid.
Changes in polarity at the immediate binding site in protein bovine serum albumin (BSA) produces distinct changes in the solvent polarity-dependent emission band of fluorescence probe E-3-(4-dimethylamino-naphthalen-1-yl)-acrylic acid. Steady-state spectroscopy and time-resolved spectroscopy have been used to investigate this binding process. Attaching the probe to BSA and then monitoring its spectral changes with increasing urea concentration and raising temperature has also tracked the denaturation of BSA chemically and thermally. The polarity of the microenvironment was investigated employing the Reichardt E(T)(30) scale. Fluorescence anisotropy, red edge excitation shifts and acrylamide-induced quenching of fluorescence have been exploited to gain better insight into this binding process.
24052464
Chemically induced unfolding of bovine serum albumin by urea and sodium dodecyl sulfate: a spectral study with the polarity-sensitive charge-transfer fluorescent probe (E)-3-(4-methylaminophenyl)acrylic acid methyl ester.
Sensitivity of the charge-transfer (CT) band of the fluorescence probe (E)-3-(4-methylaminophenyl)acrylic acid methyl ester (MAPAME) towards the polarity of its immediate environment is employed to investigate the binding interaction of the probe with bovine serum albumin (BSA) and uncoiling of BSA by the denaturants urea and sodium dodecyl sulfate micelles. Binding of the probe with BSA produces a blue shift and enhanced intensity of the CT emission band which clearly point toward a decrease in polarity of the immediate environment of MAPAME. This is expected, since binding with BSA moves the probe from a polar water environment to a much less polar, hydrophobic protein interior, where the CT band is expected to be blue-shifted. Higher intensity arises due to fewer non-radiative decay paths available to the probe in the hydrophobic protein environment. Chemically induced unfolding of BSA by urea and sodium dodecyl sulfate is tracked by monitoring the induced spectral changes of the protein-bound probe MAPAME. Red-edge excitation shift or REES, fluorescence resonance energy transfer (FRET) and anisotropy measurements are used to investigate and monitor these binding and unfolding processes.
40815524
Constrained photophysics of partially and fully encapsulated charge transfer probe (E)-3-(4-Methylaminophenyl) acrylic acid methyl ester inside cyclodextrin nano-cavities: evidence of cyclodextrins cavity dependent complex stoichiometry.
The polarity sensitive intra-molecular charge transfer (ICT) emission from (E)-3-(4-Methylaminophenyl) acrylic acid methyl ester (MAPAME) is found to show distinct changes once introduced into the nano-cavities of cyclodextrins in aqueous environment. Movement of the molecule from the more polar aqueous environment to the less polar, hydrophobic cyclodextrin interior is marked by the blue shift of the CT emission band with simultaneous fluorescence intensity enhancement. The emission spectral changes on complexation with the α- and β-CD show different stoichiometries as observed from the Benesi-Hildebrand plots. Fluorescence anisotropy and lifetime measurements were performed to probe the different behaviors of MAPAME in aqueous α- and β-CD solutions.
26613213
Fluorescent Probing of Protein Bovine Serum Albumin Stability and Denaturation Using Polarity Sensitive Spectral Response of a Charge Transfer Probe
The polarity sensitive photo-induced intra-molecular charge transfer (ICT) fluorescence probe (E)-3-(4-methylamino-phenyl)-acrylic acid ethyl ester (MAPAEE) has been used to study the model protein Bovine Serum Albumin (BSA) in its native and thermal and urea induced denatured states. The interaction between BSA and the regular surfactant Sodium Dodecyl Sulphate (SDS) as well as the biologically relevant steroid-based amphiphile Sodium Deoxycholate (NaDC) has also been very keenly followed using this ICT probe. The variation of micellar properties of both SDS and NaDC with increasing ionic strengths and in presence of the chaotrope urea has also been well documemted by the same probe. Steady-state spectroscopy, FRET, and fluorescence anisotropy measurements have been used to gain better insight into these processes and the molecule MAPAEE to be a full-bodied fluorescent probe for studying such intricate biological systems, their properties and interactions.
31255336
Abnormal radiological features in a multiple myeloma patient: a case report and radiological review of myelomas.
Multiple myeloma is the prototype of malignant monoclonal gammopathies. The most common skeletal sites are pelvis, skull, spine, ribs and femoral and humeral shafts. The classic radiographic presentation of multiple myeloma is lytic skeletal lesions. Other types of presentation include sclerotic and porotic changes. Primary sclerotic manifestations are rare and occur in only 3% of cases. Although exceptional, multiple myeloma must be borne in mind in the presence of bone sclerosis. This report presents a patient with multiple myeloma with a sunburst/hair-on-end pattern on the radiograph and sclerotic skeletal lesions.
19083493
Assessment of duration of immunity in crossbred cattle immunized with glycoproteins isolated from Hyalomma anatolicum anatolicum and Boophilus microplus
To develop immunoprophylactic measures against multi-tick infestation, two glycoproteins of 34 and 29 kDa were isolated from the larvae of Hyalomma anatolicum anatolicum and Boophilus microplus, respectively, and assessed for their efficacy against experimental challenge infestations. The synergistic effect of the antigens in the presence of incomplete Freund’s adjuvant was found to confer protection (DT%) in animals against 56.48% of larvae and 52% of adults of H. a. anatolicum, while the effect was 40% against adults of B. microplus. The efficacy (E%) of the antigens in combination against larvae and adults of H. a. anatolicum was calculated as 70% and 64.3%, respectively, and 63% against adults of B. microplus. A direct correlation between anti-glycoprotein antibody response and protection against infestation was observed. Western blot analysis detected specific antigen in the sera of animals of group A. The antigens in combination with incomplete Freund’s adjuvant could protect animals from H. a. anatolicum and B. microplus infestations for at least 30 weeks. The possibility of employing the vaccination strategy in Indian conditions is discussed.
43633481
Interactions of Escherichia coli thioredoxin, the processivity factor, with bacteriophage T7 DNA polymerase and helicase.
Escherichia coli thioredoxin binds to a unique flexible loop of 71 amino acid residues, designated the thioredoxin binding domain (TBD), located in the thumb subdomain of bacteriophage T7 gene 5 DNA polymerase. The initial designation of thioredoxin as a processivity factor was premature. Rather it remodels the TBD for interaction with DNA and the other replication proteins. The binding of thioredoxin exposes a number of basic residues on the TBD that lie over the duplex region of the primer-template and increases the processivity of nucleotide polymerization. Two small solvent-exposed loops (loops A and B) located within TBD electrostatically interact with the acidic C-terminal tail of T7 gene 4 helicase-primase, an interaction that is enhanced by the binding of thioredoxin. Several basic residues on the surface of thioredoxin in the polymerase-thioredoxin complex lie in close proximity to the TBD. One of these residues, lysine 36, is located proximal to loop A. The substitution of glutamate for lysine has a dramatic effect on the binding of gene 4 helicase to a DNA polymerase-thioredoxin complex lacking charges on loop B; binding is decreased 15-fold relative to that observed with wild-type thioredoxin. This defective interaction impairs the ability of T7 DNA polymerase-thioredoxin together with T7 helicase to mediate strand displacement synthesis. This is the first demonstration that thioredoxin interacts with replication proteins other than T7 DNA polymerase.
46313714
Interaction of trypsin with sodium dodecyl sulfate in aqueous medium: a conformational view.
The conformational behavior of a globular protein, trypsin has been studied in presence of an anionic surfactant, sodium dodecyl sulfate (SDS) in aqueous medium by different techniques, such as, viscometry, circular dichroism, fluorimetry, Fourier transform infra-red, UV-vis absorption, dynamic light scattering and nuclear magnetic resonance. The results indicate that the viscosity of the mixture increases above the critical micelle concentration of SDS micelle supporting an expansion of a protein coil in the cluster. The spectroscopic techniques show the change of the conformation, i.e., the change of the values of alpha-helicity, beta-sheet, and random-coil of trypsin in the presence of SDS, and ultimately unfolding of trypsin occurs due to strong electrostatic repulsion of micellar clusters of the protein-surfactant complexes.
27300590
Identification of motor areas of the cat cerebral cortex based on studies of cortical stimulation and corticospinal connections.
The location and topography of motor areas in the cat cerebral cortex were studied by electrical stimulation of the cortex in five animals, and by the injection of retrograde tracers into the spinal cord of four animals. Movements evoked by intracortical microstimulation (ICMS) of the anterior, posterior and lateral sigmoid gyri, both banks of the cruciate sulcus and the dorsal bank of the presylvian sulcus were observed in anaesthetized cats. Fluorescent tracers (Fast Blue and/or Diamadino Yellow) were injected into the lateral funiculus in the second cervical segment, into the gray matter of cervical segments C3-T1 and/or into the gray matter of lumbar segments L2-S1. Contraction of the contralateral forelimb, hindlimb or facial muscles was observed following electrical stimulation of several cytoarchitectonic areas: 4 gamma, 4 delta, 6a alpha, 6a gamma, and 3a. These findings suggested representations of contralateral forelimb and hindlimb movements in areas 4 gamma and 4 delta, and of the contralateral forelimb muscles in areas 6a alpha and 6a gamma. Corticospinal neurons were located in all the above cytoarchitectonic areas as well as in areas 3b, 1, 2, 2pri, and 5. Large numbers of neurons were labeled in areas 4 gamma and 4 delta, and moderate labeling was observed in areas 6a gamma and 6a alpha. Corticospinal neurons projecting to cervical and lumbar segments were located in areas 4 gamma and 4 delta, while those projecting only to cervical segments were detected in areas 6a alpha and 6a gamma. Based on these findings it is proposed that within the motor cortex of the cat there are representations of limb movements in several cytoarchitectonic subdivisions. Many of these representations may be candidate secondary motor areas.