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Bjorn T Stokke - One of the best experts on this subject based on the ideXlab platform.
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Structural properties of polyC–scleroglucan complexes
Biopolymers, 2005Co-Authors: Marit Sletmoen, Bjorn T StokkeAbstract:Successive changes of solvent conditions can be used to dissociate and reassociate the triple-helical structure of (1,3)-beta-D-glucans. Ultramicroscopic techniques have revealed a blend of circular and other structures following renaturation. When this solvent exchange process is carried out in the presence of certain Polynucleotides, the process creates a novel macromolecular complex. Here, we use size exclusion chromatography (SEC) to study such (1,3)-beta-D-glucan-Polynucleotide complexes. Online multi-angle laser-light scattering (MALLS) and refractive index (RI) detectors allowed determination of molecular weight and radius of gyration of the molecules. An ultraviolet (UV) detector allowed specific detection of the Polynucleotide. The poly-cytidylic acid (poly C) shifted to coelution with the linear fraction of the scleroglucan following the renaturation of poly C-scleroglucan blends, indicating that poly C is incorporated in linear, but not in circular, structures of scleroglucan. This conclusion was consistent with AFM topographs that revealed a decreased fraction of circular structures upon addition of poly C during the renaturation process. The combined information about radius of gyration (R(g)) and molecular weight (M(w)) allowed us to conclude that the poly C-scleroglucan complexes are more dense and have a higher persistence length than linear scleroglucan triple helixes. The experimentally determined mass per unit length was used as a basis for elucidating possible molecular arrangements within the poly C-scleroglucan complex.
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structural properties of polyc scleroglucan complexes
Biopolymers, 2005Co-Authors: Marit Sletmoen, Bjorn T StokkeAbstract:Successive changes of solvent conditions can be used to dissociate and reassociate the triple-helical structure of (1,3)-beta-D-glucans. Ultramicroscopic techniques have revealed a blend of circular and other structures following renaturation. When this solvent exchange process is carried out in the presence of certain Polynucleotides, the process creates a novel macromolecular complex. Here, we use size exclusion chromatography (SEC) to study such (1,3)-beta-D-glucan-Polynucleotide complexes. Online multi-angle laser-light scattering (MALLS) and refractive index (RI) detectors allowed determination of molecular weight and radius of gyration of the molecules. An ultraviolet (UV) detector allowed specific detection of the Polynucleotide. The poly-cytidylic acid (poly C) shifted to coelution with the linear fraction of the scleroglucan following the renaturation of poly C-scleroglucan blends, indicating that poly C is incorporated in linear, but not in circular, structures of scleroglucan. This conclusion was consistent with AFM topographs that revealed a decreased fraction of circular structures upon addition of poly C during the renaturation process. The combined information about radius of gyration (R(g)) and molecular weight (M(w)) allowed us to conclude that the poly C-scleroglucan complexes are more dense and have a higher persistence length than linear scleroglucan triple helixes. The experimentally determined mass per unit length was used as a basis for elucidating possible molecular arrangements within the poly C-scleroglucan complex.
Marit Sletmoen - One of the best experts on this subject based on the ideXlab platform.
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Structural properties of polyC–scleroglucan complexes
Biopolymers, 2005Co-Authors: Marit Sletmoen, Bjorn T StokkeAbstract:Successive changes of solvent conditions can be used to dissociate and reassociate the triple-helical structure of (1,3)-beta-D-glucans. Ultramicroscopic techniques have revealed a blend of circular and other structures following renaturation. When this solvent exchange process is carried out in the presence of certain Polynucleotides, the process creates a novel macromolecular complex. Here, we use size exclusion chromatography (SEC) to study such (1,3)-beta-D-glucan-Polynucleotide complexes. Online multi-angle laser-light scattering (MALLS) and refractive index (RI) detectors allowed determination of molecular weight and radius of gyration of the molecules. An ultraviolet (UV) detector allowed specific detection of the Polynucleotide. The poly-cytidylic acid (poly C) shifted to coelution with the linear fraction of the scleroglucan following the renaturation of poly C-scleroglucan blends, indicating that poly C is incorporated in linear, but not in circular, structures of scleroglucan. This conclusion was consistent with AFM topographs that revealed a decreased fraction of circular structures upon addition of poly C during the renaturation process. The combined information about radius of gyration (R(g)) and molecular weight (M(w)) allowed us to conclude that the poly C-scleroglucan complexes are more dense and have a higher persistence length than linear scleroglucan triple helixes. The experimentally determined mass per unit length was used as a basis for elucidating possible molecular arrangements within the poly C-scleroglucan complex.
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structural properties of polyc scleroglucan complexes
Biopolymers, 2005Co-Authors: Marit Sletmoen, Bjorn T StokkeAbstract:Successive changes of solvent conditions can be used to dissociate and reassociate the triple-helical structure of (1,3)-beta-D-glucans. Ultramicroscopic techniques have revealed a blend of circular and other structures following renaturation. When this solvent exchange process is carried out in the presence of certain Polynucleotides, the process creates a novel macromolecular complex. Here, we use size exclusion chromatography (SEC) to study such (1,3)-beta-D-glucan-Polynucleotide complexes. Online multi-angle laser-light scattering (MALLS) and refractive index (RI) detectors allowed determination of molecular weight and radius of gyration of the molecules. An ultraviolet (UV) detector allowed specific detection of the Polynucleotide. The poly-cytidylic acid (poly C) shifted to coelution with the linear fraction of the scleroglucan following the renaturation of poly C-scleroglucan blends, indicating that poly C is incorporated in linear, but not in circular, structures of scleroglucan. This conclusion was consistent with AFM topographs that revealed a decreased fraction of circular structures upon addition of poly C during the renaturation process. The combined information about radius of gyration (R(g)) and molecular weight (M(w)) allowed us to conclude that the poly C-scleroglucan complexes are more dense and have a higher persistence length than linear scleroglucan triple helixes. The experimentally determined mass per unit length was used as a basis for elucidating possible molecular arrangements within the poly C-scleroglucan complex.
Erkki Holtta - One of the best experts on this subject based on the ideXlab platform.
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phosphorylation of okazaki like dna fragments in mammalian cells and role of polyamines in the processing of this dna
The EMBO Journal, 1996Co-Authors: P Pohjanpelto, Erkki HolttaAbstract:In mammalian cells DNA synthesis is more complicated than in prokaryotes and less well understood. Here we incubated intact mammalian cells (polyamine auxotrophic Chinese hamster ovary cells and primary human fibroblasts) with [32P]orthophosphate and found that, besides high molecular weight DNA, a species of low molecular weight DNA, approximately 450 bp in size, became efficiently labeled. The short DNA was labeled first, and in pulse-chase experiments the labeling was transient. The isolated small DNA fragments (RNase A-treated) were phosphorylated by T4 Polynucleotide kinase specific for Polynucleotides with 5'-OH ends. A Polynucleotide kinase phosphorylating these DNA pieces was also detected in nuclear extracts of the cells. Treatment with alkaline phosphatase removed most of the 32P label incorporated into the small DNA in vivo. Labeling with deoxyribonucleosides did not reveal these fragments. We hypothesize that the low molecular weight DNA represents Okazaki fragments and that the mammalian DNA replication machinery includes a Polynucleotide kinase phosphorylating the 5'-termini of Okazaki fragments. This would imply a novel step in DNA synthesis. We also show that depriving cells of polyamines reversibly blocks synthesis of high molecular weight DNA and leads to accumulation of the short DNA pieces, suggesting a role for polyamines in joining the Okazaki fragments.
Hyung Rang Moon - One of the best experts on this subject based on the ideXlab platform.
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Base specific complex formation of norfloxacin with DNA.
Biophysical Chemistry, 1998Co-Authors: Hyung Rang MoonAbstract:We examined the base specificity of the norfloxacin–DNA interaction by measuring the binding constant of norfloxacin to various synthetic Polynucleotides, using the Stern–Volmer and the Benesi–Hildebrand methods. The equilibrium constants were largest for poly[d(G–C)2] and poly(dG)·poly(dC), suggesting that norfloxacin binds preferentially to the G–C bases of calf thymus DNA. We also found that norfloxacin has a greater affinity for purine than for pyrimidine. The binding mode of norfloxacin to double-stranded Polynucleotide was studied using circular and linear dichroism (CD and LD). When the norfloxacin was complexed to poly[d(G–C)2], poly(dG)·poly(dC) and DNA, all of the complexes exhibited a similar weak, positive CD band and negative LD in the 300–350-nm region. A closer examination of the LD spectra suggests that the molecular plane of norfloxacin is near perpendicular relative to DNA helix axis that excludes the groove binding mode or surface binding of norfloxacin.
P Pohjanpelto - One of the best experts on this subject based on the ideXlab platform.
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phosphorylation of okazaki like dna fragments in mammalian cells and role of polyamines in the processing of this dna
The EMBO Journal, 1996Co-Authors: P Pohjanpelto, Erkki HolttaAbstract:In mammalian cells DNA synthesis is more complicated than in prokaryotes and less well understood. Here we incubated intact mammalian cells (polyamine auxotrophic Chinese hamster ovary cells and primary human fibroblasts) with [32P]orthophosphate and found that, besides high molecular weight DNA, a species of low molecular weight DNA, approximately 450 bp in size, became efficiently labeled. The short DNA was labeled first, and in pulse-chase experiments the labeling was transient. The isolated small DNA fragments (RNase A-treated) were phosphorylated by T4 Polynucleotide kinase specific for Polynucleotides with 5'-OH ends. A Polynucleotide kinase phosphorylating these DNA pieces was also detected in nuclear extracts of the cells. Treatment with alkaline phosphatase removed most of the 32P label incorporated into the small DNA in vivo. Labeling with deoxyribonucleosides did not reveal these fragments. We hypothesize that the low molecular weight DNA represents Okazaki fragments and that the mammalian DNA replication machinery includes a Polynucleotide kinase phosphorylating the 5'-termini of Okazaki fragments. This would imply a novel step in DNA synthesis. We also show that depriving cells of polyamines reversibly blocks synthesis of high molecular weight DNA and leads to accumulation of the short DNA pieces, suggesting a role for polyamines in joining the Okazaki fragments.
