The Experts below are selected from a list of 120 Experts worldwide ranked by ideXlab platform
Gregory S. Hageman - One of the best experts on this subject based on the ideXlab platform.
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Stage-specific binding of Peanut Agglutinin to aggregates of degenerating photoreceptor cells in the rd mouse retina.
Experimental eye research, 1993Co-Authors: Janet C. Blanks, Lincoln V. Johnson, Gregory S. HagemanAbstract:Peanut Agglutinin, a lectin with high binding affinity for galactose-galactosamine disaccharide, was used to monitor changes in the photoreceptor cell layer of mice with inherited retinal degeneration. Mice homozygous for the retinal degeneration (rd) gene exhibit a rapid loss of rod photoreceptor cells in the first postnatal month. Previous studies have shown that aggregates of Peanut Agglutinin-binding cells are observed in the outer nuclear layer in the retinal degenerative mouse at between postnatal days 10 and 18, a period during which massive photoreceptor degeneration occurs in this mutant. This study was performed to determine whether these Peanut Agglutinin-positive cell clusters represent degenerating photoreceptor cells or, alternatively, macrophages that have migrated into the photoreceptor cell layer. Electron microscopic cytochemistry, using horseradish-peroxidase-conjugated Peanut Agglutinin, was used to trace cellular processes of Peanut-Agglutinin-stained cell clusters. Additionally, macrophage-specific antibodies were employed to determine whether macrophages were present in the clusters. The cell clusters did not react with macrophage-specific antibodies. However, processes of cells in Peanut-Agglutinin-bound clusters could be traced by electron microscopic serial sections to both the outer limiting membrane and the outer synaptic layer. These results provide strong evidence that Peanut-Agglutinin-bound cells seen during this stage of degeneration in the rd mouse are degenerating photoreceptor cells. Since Peanut Agglutinin has been shown to bind preferentially to cone, but not to rod, photoreceptor cells, the results also suggest that the clusters may be aggregates of degenerating cones.
Sei Kwang Hahn - One of the best experts on this subject based on the ideXlab platform.
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Hyaluronate-Peanut Agglutinin Conjugates for Target-Specific Bioimaging of Colon Cancer.
Bioconjugate chemistry, 2017Co-Authors: Songeun Beack, Minsoo Cho, Young Eun Kim, G-one Ahn, Sei Kwang HahnAbstract:Colon cancer is one of the most common death-related cancers in the world. For treating colon cancer, it is crucial to detect and remove malignant lesions early. Here, we developed hyaluronate (HA)–Peanut Agglutinin (PNA) conjugates for the bioimaging of colon cancer. The HA–PNA conjugates were successfully synthesized by the coupling reaction between aldehyde-modified HA and the N-terminal amine group of PNA. For diagnostic imaging, rhodamine B (RhoB) was chemically conjugated onto PNA in HA–PNA conjugates. After intraluminal injection of HA–PNA–RhoB conjugates into tumor-bearing mice, small-sized colon cancers could be effectively visualized by ex vivo imaging with an in vivo imaging system (IVIS) and a two-photon microscope. With these results taken together, we could confirm the feasibility of HA–PNA–RhoB conjugates as a bioimaging agent for detecting colon cancers.
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Hyaluronate–Peanut Agglutinin Conjugates for Target-Specific Bioimaging of Colon Cancer
2017Co-Authors: Songeun Beack, Minsoo Cho, Young Eun Kim, G-one Ahn, Sei Kwang HahnAbstract:Colon cancer is one of the most common death-related cancers in the world. For treating colon cancer, it is crucial to detect and remove malignant lesions early. Here, we developed hyaluronate (HA)–Peanut Agglutinin (PNA) conjugates for the bioimaging of colon cancer. The HA–PNA conjugates were successfully synthesized by the coupling reaction between aldehyde-modified HA and the N-terminal amine group of PNA. For diagnostic imaging, rhodamine B (RhoB) was chemically conjugated onto PNA in HA–PNA conjugates. After intraluminal injection of HA–PNA–RhoB conjugates into tumor-bearing mice, small-sized colon cancers could be effectively visualized by ex vivo imaging with an in vivo imaging system (IVIS) and a two-photon microscope. With these results taken together, we could confirm the feasibility of HA–PNA–RhoB conjugates as a bioimaging agent for detecting colon cancers
Snjezana Stolnik - One of the best experts on this subject based on the ideXlab platform.
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Investigation of the interaction between Peanut Agglutinin and synthetic glycopolymeric multivalent ligands
Organic & biomolecular chemistry, 2005Co-Authors: Moira Ambrosi, Neil R. Cameron, Benjamin G. Davis, Snjezana StolnikAbstract:The interaction between synthetic glycoplymers bearing β-D-galactose side groups and the lectin Peanut Agglutinin (PNA) was investigated by UV-difference spectroscopy and isothermal titration calorimetry (ITC). UV-difference spectroscopy indicated that the polymer–lectin interaction was stronger than that between PNA and either the corresponding monomer, D-galactose or D-lactose. The thermodynamics of binding (K, ΔG, ΔH, ΔS and n) were determined from ITC data by fitting with a two-site, non-cooperative binding model. It was found that the glycopolymer displayed around a 50 times greater affinity for the lectin than the parent carbohydrate, and around 10 times greater than the monomer, on a valency-corrected basis. Binding was found to be entropically driven, and was accompanied by aggregation and precipitation of protein molecules. Furthermore, interesting differences between polymers prepared either from deacetylated monomers, or by deacetylation of pre-formed polymers, were found.
Avadhesha Surolia - One of the best experts on this subject based on the ideXlab platform.
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Dynamic light scattering study of Peanut Agglutinin: size, shape and urea denaturation.
Journal of biosciences, 2006Co-Authors: Sagarika Dev, Avadhesha SuroliaAbstract:Peanut Agglutinin (PNA)is a homotetrameric protein with a unique open quaternary structure. PNA shows non-two state profile in chaotrope induced denaturation. It passes through a monomeric molten globule like state before complete denaturation (Reddy et al 1999). This denaturation profile is associated with the change in hydrodynamic radius of the native protein. Though the molten globule-like state is monomeric in nature it expands in size due to partial denaturation. The size and shape of the native PNA as well as the change in hydrodynamic radius of the protein during denaturation has been studied by dynamic light scattering (DLS). The generation of two species is evident from the profile of hydrodynamic radii. This study also reveals the extent of compactness of the intermediate state.
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Thermodynamic analysis of three state denaturation of Peanut Agglutinin.
IUBMB life, 2006Co-Authors: Sagarika Dev, Devi K Nirmala, Sharmistha Sinha, Avadhesha SuroliaAbstract:Peanut Agglutinin (PNA) is a homotetrameric protein with a very unusual open quaternary structure. During denaturation, it first dissociates into a molten globule like state, which subsequently undergoes complete denaturation. Urea denaturation of PNA at neutral pH has been studied by intrinsic fluorescence spectroscopy and has been fitted to a three state model, A(4) double left right arrow 4I double left right arrow 4U, to get all the relevant thermodynamic parameters. Urea denaturation leads to continuous red shift of wavelength maxima. The molten globule like state is formed in a short range of urea concentration. Refolding of the denatured PNA has been attempted by intrinsic fluorescence study. Refolding by instantaneous dilution shows the occurrence of the formation of an intermediate at a relatively rapid rate, within few seconds. The transition from PNA tetramer to molten globule like state is found to have a Delta G value of similar to 33 kcal/mole while it is similar to 8 kcal/mole for the transition from molten globule like state to a completely denatured state. This in turn indicates that the tetramerization in PNA contributes significantly to the stability of the oligomer.
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Thermal stability and mode of oligomerization of the tetrameric Peanut Agglutinin: a differential scanning calorimetry study.
Biochemistry, 1999Co-Authors: Bhanuprakash G Reddy, Satish Bharadwaj, Avadhesha SuroliaAbstract:Peanut Agglutinin is a homotetrameric legume lectin. The crystal structure of Peanut Agglutinin shows that the four subunits associate in an unusual manner, giving rise to open quaternary structure [Banarjee, R., et al. (1994) Proc. Natl. Acad. Sci. U.S.A. 91, 227-231]. The thermal unfolding of Peanut Agglutinin has been characterized by differential scanning calorimetry and gel filtration to elucidate its thermal stability and its mode of oligomerization. The unfolding process is reversible and could be described by a three-state model with two transitions occurring at around 331 and 336 K. For the tetramer, the ratio of $\Delta H_c/ \Delta H_v$ for the first transition is close to 4 and for the second transition is close to 0.25, suggesting that 4 and 0.25 cooperative unit(s) of the tetramer are involved in the first and second transitions, respectively. The agreement between the model-independent$ \Delta H_v(S)$ determined from the values of the temperatures of the peak maximum$(T_{p1})$ with the protein concentration with the values of $\Delta H_v$ obtained from the fit of the data to the transition confirms that the first peak is associated with the dissociation of Peanut Agglutinin tetramers $(A_4)$ to "folded" monomers (4A), whereas the second peak describes the unfolding (4U) of these monomers. The overall process for the thermal unfolding of Peanut Agglutinin could therefore be summarized as $A_4\leftrightarrow 4A\leftrightarrow 4 U $. Gel filtration studies confirm this process, as Peanut Agglutinin elutes as a tetramer up to $50^oC$, and at and above $56^oC$ ($T_m$ of first transition), it elutes at a position commensurate with that of the folded monomer of Peanut Agglutinin. The unfolding behavior of Peanut Agglutinin in the presence of saturating amounts of carbohydrate ligands is similar to that observed for the unligated form. The temperature of maximal stability of the Peanut Agglutinin tetramer at pH 7.4 is calculated to be around $33^oC$ with a maximal free energy of stabilization of 8.70 kcal/mol. The results demonstrate that unfolding of Peanut Agglutinin goes through two distinct phases with folded monomer being the intermediate.
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Cloning by genomic PCR and production of Peanut Agglutinin in Escherichia coli
Gene, 1994Co-Authors: Vivek Sharma, Avadhesha SuroliaAbstract:Using the polymerase chain reaction, the coding sequence for Peanut Agglutinin (PNA) was cloned and expressed in Escherichia coli. Amplified PNA is identical to previously reported cDNA, suggesting the absence of any introns in PNA gene. Recombinant (re-) PNA forms inclusion bodies in E. coli. Production of PNA was confirmed by probing Western blots with polyclonal anti-PNA immunoglobulin G. Inclusion bodies were solubilized with 6 M guanidine-HCl and renatured by rapid dilution in the presence of metal ions. The renatured lectin was then purified by affinity chromatography. The re-lectin shows carbohydrate-binding properties similar to the natural PNA. This expression system provides a model for future mutagenesis studies of the carbohydrate-binding site and thus facilitates ongoing efforts to explore the molecular basis for the specificity of lectin-carbohydrate interaction.
Janet C. Blanks - One of the best experts on this subject based on the ideXlab platform.
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Stage-specific binding of Peanut Agglutinin to aggregates of degenerating photoreceptor cells in the rd mouse retina.
Experimental eye research, 1993Co-Authors: Janet C. Blanks, Lincoln V. Johnson, Gregory S. HagemanAbstract:Peanut Agglutinin, a lectin with high binding affinity for galactose-galactosamine disaccharide, was used to monitor changes in the photoreceptor cell layer of mice with inherited retinal degeneration. Mice homozygous for the retinal degeneration (rd) gene exhibit a rapid loss of rod photoreceptor cells in the first postnatal month. Previous studies have shown that aggregates of Peanut Agglutinin-binding cells are observed in the outer nuclear layer in the retinal degenerative mouse at between postnatal days 10 and 18, a period during which massive photoreceptor degeneration occurs in this mutant. This study was performed to determine whether these Peanut Agglutinin-positive cell clusters represent degenerating photoreceptor cells or, alternatively, macrophages that have migrated into the photoreceptor cell layer. Electron microscopic cytochemistry, using horseradish-peroxidase-conjugated Peanut Agglutinin, was used to trace cellular processes of Peanut-Agglutinin-stained cell clusters. Additionally, macrophage-specific antibodies were employed to determine whether macrophages were present in the clusters. The cell clusters did not react with macrophage-specific antibodies. However, processes of cells in Peanut-Agglutinin-bound clusters could be traced by electron microscopic serial sections to both the outer limiting membrane and the outer synaptic layer. These results provide strong evidence that Peanut-Agglutinin-bound cells seen during this stage of degeneration in the rd mouse are degenerating photoreceptor cells. Since Peanut Agglutinin has been shown to bind preferentially to cone, but not to rod, photoreceptor cells, the results also suggest that the clusters may be aggregates of degenerating cones.