The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform
Thomas A. Kunkel - One of the best experts on this subject based on the ideXlab platform.
-
Ribonucleotide incorporation into DNA during DNA replication and its consequences.
Critical reviews in biochemistry and molecular biology, 2021Co-Authors: Zhi-xiong Zhou, Jessica S Williams, Scott A. Lujan, Thomas A. KunkelAbstract:Ribonucleotides are the most abundant non-canonical nucleotides in the genome. Their vast presence and influence over genome biology is becoming increasingly appreciated. Here we review the recent progress made in understanding their genomic presence, incorporation characteristics and usefulness as biomarkers for polymerase enzymology. We also discuss Ribonucleotide processing, the genetic consequences of unrepaired Ribonucleotides in DNA and evidence supporting the significance of their transient presence in the nuclear genome.
-
Ribonucleotide excision repair is essential to prevent squamous cell carcinoma of the skin
Cancer Research, 2018Co-Authors: Bjorn Hiller, Anja Hoppe, Christa Haase, Christina Hiller, Nadja Schubert, Werner Muller, Martin A M Reijns, Andrew P Jackson, Thomas A. KunkelAbstract:Because of imperfect discrimination against ribonucleoside triphosphates by the replicative DNA polymerases, large numbers of Ribonucleotides are incorporated into the eukaryotic nuclear genome during S-phase. Ribonucleotides, by far the most common DNA lesion in replicating cells, destabilize the DNA, and an evolutionarily conserved DNA repair machinery, Ribonucleotide excision repair (RER), ensures Ribonucleotide removal. Whereas complete lack of RER is embryonically lethal, partial loss-of-function mutations in the genes encoding subunits of RNase H2, the enzyme essential for initiation of RER, cause the SLE-related type I interferonopathy Aicardi-Goutieres syndrome. Here, we demonstrate that selective inactivation of RER in mouse epidermis results in spontaneous DNA damage and epidermal hyperproliferation associated with loss of hair follicle stem cells and hair follicle function. The animals developed keratinocyte intraepithelial neoplasia and invasive squamous cell carcinoma with complete penetrance, despite potent type I interferon production and skin inflammation. These results suggest that compromises to RER-mediated genome maintenance might represent an important tumor-promoting principle in human cancer.Significance: Selective inactivation of Ribonucleotide excision repair by loss of RNase H2 in the murine epidermis results in spontaneous DNA damage, type I interferon response, skin inflammation, and development of squamous cell carcinoma. Cancer Res; 78(20); 5917-26. ©2018 AACR.
-
Studying Ribonucleotide Incorporation: Strand-specific Detection of Ribonucleotides in the Yeast Genome and Measuring Ribonucleotide-induced Mutagenesis.
Journal of visualized experiments : JoVE, 2018Co-Authors: Zhi-xiong Zhou, Jessica S Williams, Thomas A. KunkelAbstract:The presence of Ribonucleotides in nuclear DNA has been shown to be a source of genomic instability. The extent of Ribonucleotide incorporation can be assessed by alkaline hydrolysis and gel electrophoresis as RNA is highly susceptible to hydrolysis in alkaline conditions. This, in combination with Southern blot analysis can be used to determine the location and strand into which the Ribonucleotides have been incorporated. However, this procedure is only semi-quantitative and may not be sensitive enough to detect small changes in Ribonucleotide content, although strand-specific Southern blot probing improves the sensitivity. As a measure of one of the most striking biological consequences of Ribonucleotides in DNA, spontaneous mutagenesis can be analyzed using a forward mutation assay. Using appropriate reporter genes, rare mutations that results in the loss of function can be selected and overall and specific mutation rates can be measured by combining data from fluctuation experiments with DNA sequencing of the reporter gene. The fluctuation assay is applicable to examine a wide variety of mutagenic processes in specific genetic background or growth conditions.
-
Studying Topoisomerase 1-Mediated Damage at Genomic Ribonucleotides.
Methods in molecular biology (Clifton N.J.), 2017Co-Authors: Jessica S Williams, Thomas A. KunkelAbstract:Ribonucleotides incorporated into DNA by the DNA polymerases can be incised by Topoisomerase 1 (Top1) to initiate removal of Ribonucleotides from the genome. This Top1-dependent Ribonucleotide removal has been demonstrated to result in multiple forms of genome instability in yeast. Here, we describe both quantitative and qualitative assays to identify mutations and other forms of DNA damage resulting from Top1-cleavage at unrepaired genomic Ribonucleotides.
-
Processing Ribonucleotides incorporated during eukaryotic DNA replication.
Nature reviews. Molecular cell biology, 2016Co-Authors: Jessica S Williams, Scott A. Lujan, Thomas A. KunkelAbstract:The information encoded in DNA is influenced by the presence of non-canonical nucleotides, the most frequent of which are Ribonucleotides. In this Review, we discuss recent discoveries about Ribonucleotide incorporation into DNA during replication by the three major eukaryotic replicases, DNA polymerases α, δ and e. The presence of Ribonucleotides in DNA causes short deletion mutations and may result in the generation of single- and double-strand DNA breaks, leading to genome instability. We describe how these Ribonucleotides are removed from DNA through Ribonucleotide excision repair and by topoisomerase I. We discuss the biological consequences and the physiological roles of Ribonucleotides in DNA, and consider how deficiencies in their removal from DNA may be important in the aetiology of disease.
Anders R Clausen - One of the best experts on this subject based on the ideXlab platform.
-
Ribonucleotides incorporated by the yeast mitochondrial DNA polymerase are not repaired.
Proceedings of the National Academy of Sciences of the United States of America, 2017Co-Authors: Paulina H. Wanrooij, Anders R Clausen, Martin K. M. Engqvist, Josefin M. E. Forslund, Clara Navarrete, Anna Karin Nilsson, Juhan Sedman, Sjoerd Wanrooij, Andrei ChabesAbstract:Incorporation of Ribonucleotides into DNA during genome replication is a significant source of genomic instability. The frequency of Ribonucleotides in DNA is determined by deoxyribonucleoside triphosphate/ribonucleoside triphosphate (dNTP/rNTP) ratios, by the ability of DNA polymerases to discriminate against Ribonucleotides, and by the capacity of repair mechanisms to remove incorporated Ribonucleotides. To simultaneously compare how the nuclear and mitochondrial genomes incorporate and remove Ribonucleotides, we challenged these processes by changing the balance of cellular dNTPs. Using a collection of yeast strains with altered dNTP pools, we discovered an inverse relationship between the concentration of individual dNTPs and the amount of the corresponding Ribonucleotides incorporated in mitochondrial DNA, while in nuclear DNA the Ribonucleotide pattern was only altered in the absence of Ribonucleotide excision repair. Our analysis uncovers major differences in Ribonucleotide repair between the two genomes and provides concrete evidence that yeast mitochondria lack mechanisms for removal of Ribonucleotides incorporated by the mtDNA polymerase. Furthermore, as cytosolic dNTP pool imbalances were transmitted equally well into the nucleus and the mitochondria, our results support a view of the cytosolic and mitochondrial dNTP pools in frequent exchange.
-
Nucleotide pools dictate the identity and frequency of Ribonucleotide incorporation in mitochondrial DNA.
PLoS genetics, 2017Co-Authors: Anna-karin Berglund, Martin K. M. Engqvist, Clara Navarrete, Emily Hoberg, Zsolt Szilagyi, Robert W. Taylor, Claes M. Gustafsson, Maria Falkenberg, Anders R ClausenAbstract:Previous work has demonstrated the presence of Ribonucleotides in human mitochondrial DNA (mtDNA) and in the present study we use a genome-wide approach to precisely map the location of these. We find that Ribonucleotides are distributed evenly between the heavy- and light-strand of mtDNA. The relative levels of incorporated Ribonucleotides reflect that DNA polymerase γ discriminates the four Ribonucleotides differentially during DNA synthesis. The observed pattern is also dependent on the mitochondrial deoxyRibonucleotide (dNTP) pools and disease-causing mutations that change these pools alter both the absolute and relative levels of incorporated Ribonucleotides. Our analyses strongly suggest that DNA polymerase γ-dependent incorporation is the main source of Ribonucleotides in mtDNA and argues against the existence of a mitochondrial Ribonucleotide excision repair pathway in human cells. Furthermore, we clearly demonstrate that when dNTP pools are limiting, Ribonucleotides serve as a source of building blocks to maintain DNA replication. Increased levels of embedded Ribonucleotides in patient cells with disturbed nucleotide pools may contribute to a pathogenic mechanism that affects mtDNA stability and impair new rounds of mtDNA replication.
-
Measuring Ribonucleotide incorporation into DNA in vitro and in vivo
Methods in Molecular Biology, 2015Co-Authors: Anders R Clausen, Jessica S Williams, Thomas A. KunkelAbstract:Ribonucleotides are incorporated into genomes by DNA polymerases, they can be removed, and if not removed, they can have deleterious and beneficial consequences. Here, we describe an assay to quantify stable Ribonucleotide incorporation by DNA polymerases in vitro, and an assay to probe for Ribonucleotides in each of the two DNA strands of the yeast nuclear genome.
-
structure function analysis of Ribonucleotide bypass by b family dna replicases
Proceedings of the National Academy of Sciences of the United States of America, 2013Co-Authors: Anders R Clausen, Michael S. Murray, Andrew R. Passer, Lars C. Pedersen, Thomas A. KunkelAbstract:Ribonucleotides are frequently incorporated into DNA during replication, they are normally removed, and failure to remove them results in replication stress. This stress correlates with DNA polymerase (Pol) stalling during bypass of Ribonucleotides in DNA templates. Here we demonstrate that stalling by yeast replicative Pols δ and e increases as the number of consecutive template Ribonucleotides increases from one to four. The homologous bacteriophage RB69 Pol also stalls during Ribonucleotide bypass, with a pattern most similar to that of Pol e. Crystal structures of an exonuclease-deficient variant of RB69 Pol corresponding to multiple steps in single Ribonucleotide bypass reveal that increased stalling is associated with displacement of Tyr391 and an unpreferred C2´-endo conformation for the ribose. Even less efficient bypass of two consecutive Ribonucleotides in DNA correlates with similar movements of Tyr391 and displacement of one of the Ribonucleotides along with the primer-strand DNA backbone. These structure–function studies have implications for cellular signaling by Ribonucleotides, and they may be relevant to replication stress in cells defective in Ribonucleotide excision repair, including humans suffering from autoimmune disease associated with RNase H2 defects.
-
Structure–function analysis of Ribonucleotide bypass by B family DNA replicases
Proceedings of the National Academy of Sciences of the United States of America, 2013Co-Authors: Anders R Clausen, Michael S. Murray, Andrew R. Passer, Lars C. Pedersen, Thomas A. KunkelAbstract:Ribonucleotides are frequently incorporated into DNA during replication, they are normally removed, and failure to remove them results in replication stress. This stress correlates with DNA polymerase (Pol) stalling during bypass of Ribonucleotides in DNA templates. Here we demonstrate that stalling by yeast replicative Pols δ and e increases as the number of consecutive template Ribonucleotides increases from one to four. The homologous bacteriophage RB69 Pol also stalls during Ribonucleotide bypass, with a pattern most similar to that of Pol e. Crystal structures of an exonuclease-deficient variant of RB69 Pol corresponding to multiple steps in single Ribonucleotide bypass reveal that increased stalling is associated with displacement of Tyr391 and an unpreferred C2´-endo conformation for the ribose. Even less efficient bypass of two consecutive Ribonucleotides in DNA correlates with similar movements of Tyr391 and displacement of one of the Ribonucleotides along with the primer-strand DNA backbone. These structure–function studies have implications for cellular signaling by Ribonucleotides, and they may be relevant to replication stress in cells defective in Ribonucleotide excision repair, including humans suffering from autoimmune disease associated with RNase H2 defects.
Jessica S Williams - One of the best experts on this subject based on the ideXlab platform.
-
Ribonucleotide incorporation into DNA during DNA replication and its consequences.
Critical reviews in biochemistry and molecular biology, 2021Co-Authors: Zhi-xiong Zhou, Jessica S Williams, Scott A. Lujan, Thomas A. KunkelAbstract:Ribonucleotides are the most abundant non-canonical nucleotides in the genome. Their vast presence and influence over genome biology is becoming increasingly appreciated. Here we review the recent progress made in understanding their genomic presence, incorporation characteristics and usefulness as biomarkers for polymerase enzymology. We also discuss Ribonucleotide processing, the genetic consequences of unrepaired Ribonucleotides in DNA and evidence supporting the significance of their transient presence in the nuclear genome.
-
Studying Ribonucleotide Incorporation: Strand-specific Detection of Ribonucleotides in the Yeast Genome and Measuring Ribonucleotide-induced Mutagenesis.
Journal of visualized experiments : JoVE, 2018Co-Authors: Zhi-xiong Zhou, Jessica S Williams, Thomas A. KunkelAbstract:The presence of Ribonucleotides in nuclear DNA has been shown to be a source of genomic instability. The extent of Ribonucleotide incorporation can be assessed by alkaline hydrolysis and gel electrophoresis as RNA is highly susceptible to hydrolysis in alkaline conditions. This, in combination with Southern blot analysis can be used to determine the location and strand into which the Ribonucleotides have been incorporated. However, this procedure is only semi-quantitative and may not be sensitive enough to detect small changes in Ribonucleotide content, although strand-specific Southern blot probing improves the sensitivity. As a measure of one of the most striking biological consequences of Ribonucleotides in DNA, spontaneous mutagenesis can be analyzed using a forward mutation assay. Using appropriate reporter genes, rare mutations that results in the loss of function can be selected and overall and specific mutation rates can be measured by combining data from fluctuation experiments with DNA sequencing of the reporter gene. The fluctuation assay is applicable to examine a wide variety of mutagenic processes in specific genetic background or growth conditions.
-
Studying Topoisomerase 1-Mediated Damage at Genomic Ribonucleotides.
Methods in molecular biology (Clifton N.J.), 2017Co-Authors: Jessica S Williams, Thomas A. KunkelAbstract:Ribonucleotides incorporated into DNA by the DNA polymerases can be incised by Topoisomerase 1 (Top1) to initiate removal of Ribonucleotides from the genome. This Top1-dependent Ribonucleotide removal has been demonstrated to result in multiple forms of genome instability in yeast. Here, we describe both quantitative and qualitative assays to identify mutations and other forms of DNA damage resulting from Top1-cleavage at unrepaired genomic Ribonucleotides.
-
Processing Ribonucleotides incorporated during eukaryotic DNA replication.
Nature reviews. Molecular cell biology, 2016Co-Authors: Jessica S Williams, Scott A. Lujan, Thomas A. KunkelAbstract:The information encoded in DNA is influenced by the presence of non-canonical nucleotides, the most frequent of which are Ribonucleotides. In this Review, we discuss recent discoveries about Ribonucleotide incorporation into DNA during replication by the three major eukaryotic replicases, DNA polymerases α, δ and e. The presence of Ribonucleotides in DNA causes short deletion mutations and may result in the generation of single- and double-strand DNA breaks, leading to genome instability. We describe how these Ribonucleotides are removed from DNA through Ribonucleotide excision repair and by topoisomerase I. We discuss the biological consequences and the physiological roles of Ribonucleotides in DNA, and consider how deficiencies in their removal from DNA may be important in the aetiology of disease.
-
Stimulation of Chromosomal Rearrangements by Ribonucleotides
Genetics, 2015Co-Authors: Hailey N. Conover, Jessica S Williams, Thomas A. Kunkel, Scott A. Lujan, Mary J. Chapman, Deborah A. Cornelio, Rabab Sharif, Alan B. Clark, Francheska Camilo, Juan Lucas ArguesoAbstract:We show by whole genome sequence analysis that loss of RNase H2 activity increases loss of heterozygosity (LOH) in Saccharomyces cerevisiae diploid strains harboring the pol2-M644G allele encoding a mutant version of DNA polymerase e that increases Ribonucleotide incorporation. This led us to analyze the effects of loss of RNase H2 on LOH and on nonallelic homologous recombination (NAHR) in mutant diploid strains with deletions of genes encoding RNase H2 subunits (rnh201Δ, rnh202Δ, and rnh203Δ), topoisomerase 1 (TOP1Δ), and/or carrying mutant alleles of DNA polymerases e, α, and δ. We observed an ∼7-fold elevation of the LOH rate in RNase H2 mutants encoding wild-type DNA polymerases. Strains carrying the pol2-M644G allele displayed a 7-fold elevation in the LOH rate, and synergistic 23-fold elevation in combination with rnh201Δ. In comparison, strains carrying the pol2-M644L mutation that decreases Ribonucleotide incorporation displayed lower LOH rates. The LOH rate was not elevated in strains carrying the pol1-L868M or pol3-L612M alleles that result in increased incorporation of Ribonucleotides during DNA synthesis by polymerases α and δ, respectively. A similar trend was observed in an NAHR assay, albeit with smaller phenotypic differentials. The Ribonucleotide-mediated increases in the LOH and NAHR rates were strongly dependent on TOP1. These data add to recent reports on the asymmetric mutagenicity of Ribonucleotides caused by topoisomerase 1 processing of Ribonucleotides incorporated during DNA replication.
Andrei Chabes - One of the best experts on this subject based on the ideXlab platform.
-
Ribonucleotides incorporated by the yeast mitochondrial DNA polymerase are not repaired.
Proceedings of the National Academy of Sciences of the United States of America, 2017Co-Authors: Paulina H. Wanrooij, Anders R Clausen, Martin K. M. Engqvist, Josefin M. E. Forslund, Clara Navarrete, Anna Karin Nilsson, Juhan Sedman, Sjoerd Wanrooij, Andrei ChabesAbstract:Incorporation of Ribonucleotides into DNA during genome replication is a significant source of genomic instability. The frequency of Ribonucleotides in DNA is determined by deoxyribonucleoside triphosphate/ribonucleoside triphosphate (dNTP/rNTP) ratios, by the ability of DNA polymerases to discriminate against Ribonucleotides, and by the capacity of repair mechanisms to remove incorporated Ribonucleotides. To simultaneously compare how the nuclear and mitochondrial genomes incorporate and remove Ribonucleotides, we challenged these processes by changing the balance of cellular dNTPs. Using a collection of yeast strains with altered dNTP pools, we discovered an inverse relationship between the concentration of individual dNTPs and the amount of the corresponding Ribonucleotides incorporated in mitochondrial DNA, while in nuclear DNA the Ribonucleotide pattern was only altered in the absence of Ribonucleotide excision repair. Our analysis uncovers major differences in Ribonucleotide repair between the two genomes and provides concrete evidence that yeast mitochondria lack mechanisms for removal of Ribonucleotides incorporated by the mtDNA polymerase. Furthermore, as cytosolic dNTP pool imbalances were transmitted equally well into the nucleus and the mitochondria, our results support a view of the cytosolic and mitochondrial dNTP pools in frequent exchange.
-
Topoisomerase 1-mediated removal of Ribonucleotides from nascent leading-strand DNA.
Molecular cell, 2013Co-Authors: Jessica S Williams, Andrei Chabes, Dana J. Smith, Lisette Marjavaara, Scott A. Lujan, Thomas A. KunkelAbstract:RNase H2-dependent Ribonucleotide excision repair (RER) removes Ribonucleotides incorporated during DNA replication. When RER is defective, Ribonucleotides in the nascent leading strand of the yeas ...
-
Yeast Sml1, a Protein Inhibitor of Ribonucleotide Reductase *
The Journal of biological chemistry, 1999Co-Authors: Andrei Chabes, Vladimir Domkin, Lars ThelanderAbstract:Abstract Ribonucleotide reductase (RNR) catalyzes the reduction of Ribonucleotides to deoxyRibonucleotides; this step is rate-limiting in DNA precursor synthesis. A number of regulatory mechanisms ensure optimal deoxyRibonucleotide pools, which are essential for cell viability. The best studied mechanisms are transcriptional regulation of the RNR genes during the cell cycle and in the response to DNA damage, and the allosteric regulation of Ribonucleotide reductase by nucleoside triphosphates. Recently, another mode of RNR regulation has been hypothesized in yeast. A novel protein, Sml1, was shown to bind to the Rnr1 protein of the yeast Ribonucleotide reductase; this interaction was proposed to inhibit Ribonucleotide reductase activity when DNA synthesis is not required (Zhao, X., Muller, E.G.D., and Rothstein, R. (1998) Mol. Cell 2, 329–340). Here, we use highly purified recombinant proteins to directly demonstrate that the Sml1 protein is a strong inhibitor of yeast RNR. The Sml1p specifically binds to the yeast Rnr1p in a 1:1 ratio with a dissociation constant of 0.4 μm. Interestingly, Sml1p also specifically binds to the mouse Ribonucleotide reductase R1 protein. However, the inhibition observed in an in vitro mouse Ribonucleotide reductase assay is less pronounced than the inhibition in yeast and probably occurs via a different mechanism.
-
Rnr4p, a novel Ribonucleotide reductase small-subunit protein.
Molecular and cellular biology, 1997Co-Authors: P J Wang, Lars Thelander, Andrei Chabes, R Casagrande, X C Tian, Tim C. HuffakerAbstract:Ribonucleotide reductases catalyze the formation of deoxyRibonucleotides by the reduction of the corresponding Ribonucleotides. Eukaryotic Ribonucleotide reductases are a2b2 tetramers; each of the larger, a subunits possesses binding sites for substrate and allosteric effectors, and each of the smaller, b subunits contains a binuclear iron complex. The iron complex interacts with a specific tyrosine residue to form a tyrosyl free radical which is essential for activity. Previous work has identified two genes in the yeast Saccharomyces cerevisiae, RNR1 and RNR3, that encode a subunits and one gene, RNR2, that encodes a b subunit. Here we report the identification of a second gene from this yeast, RNR4, that encodes a protein with significant similarity to the b-subunit proteins. The phenotype of rnr4 mutants is consistent with that expected for a defect in Ribonucleotide reductase; rnr4 mutants are supersensitive to the Ribonucleotide reductase inhibitor hydroxyurea and display an S-phase arrest at their restrictive temperature. rnr4 mutant extracts are deficient in Ribonucleotide reductase activity, and this deficiency can be remedied by the addition of exogenous Rnr4p. As is the case for the other RNR genes, RNR4 is induced by agents that damage DNA. However, Rnr4p lacks a number of sequence elements thought to be essential for iron binding, and mutation of the critical tyrosine residue does not affect Rnr4p function. These results suggest that Rnr4p is catalytically inactive but, nonetheless, does play a role in the Ribonucleotide reductase complex. Ribonucleotide reductases catalyze the formation of deoxyRibonucleotides by the reduction of the corresponding Ribonucleotides. Three classes of Ribonucleotide reductases have been well characterized (24). Class I enzymes are found in all eukaryotes and some prokaryotes. The best-studied class I enzyme is the Escherichia coli Ribonucleotide reductase (10, 30), an a2b2 tetramer that can be decomposed to two catalytically inactive homodimers, R1 (a2) and R2 (b2). Each of the larger a subunits possesses binding sites for substrate and allosteric effectors and also contains several redox-active cysteine residues. Each of the smaller b subunits contains a binuclear Fe(III) complex. The X-ray structure of E. coli R2 reveals that the iron ions are bridged by both an O 22 ion and the carboxyl group of a glutamate residue (22). Each iron is further liganded by two carboxyl oxygen atoms from aspartate or glutamate residues, a histidine Nd residue, and a water molecule. The recently solved structure of the mouse R2 protein indicates that the iron-binding center of eukaryotic proteins is similar to that of the E. coli protein (17). The iron complex interacts with a specific tyrosine residue to form a tyrosyl free radical which is essential for activity. The enzyme is inhibited by hydroxyurea, which specifically quenches the tyrosyl radical (19). Amino acid sequence alignments of the class 1 R2 proteins from different species identify 16 residues that are conserved in all of these proteins reported to date (7, 22). Most of these conserved residues are at the iron center or close to it. Previous work has identified two genes in the yeast Saccharomyces cerevisiae (RNR1 and RNR3) that encode R1 proteins (8) and one gene (RNR2) that encodes an R2 protein (7, 13). Here we report the identification of a second gene from this yeast, RNR4, that encodes a protein with significant similarity to the R2 proteins. However, Rnr4p lacks a number of sequence elements thought to be essential for enzymatic function. Our evidence suggests that Rnr4p is catalytically inactive but, nonetheless, does play a role in the Ribonucleotide reductase complex.
Shuhua Liu - One of the best experts on this subject based on the ideXlab platform.
-
interaction of cationic vesicle with Ribonucleotides amp adp and atp and physicochemical characterization of dodab Ribonucleotides complexes
Biophysical Chemistry, 2007Co-Authors: Shuhua LiuAbstract:Abstract The interaction between Ribonucleotides (AMP, ADP, and ATP) and cationic vesicles prepared from dioctadecyldimethylammonium bromide (DODAB) were investigated in detail. The physicochemical properties of Ribonucleotides/cationic lipid complexes were present. Gel exclusion-UV spectroscopic results showed that all the charge ratios of DODAB/Ribonucleotides (AMP, ADP, and ATP) are 2:1 when the maximal Ribonucleotides were adsorbed onto DODAB, while the molar ratios were different, e.g., 2:1 for DODAB/AMP, 4:1 for DODAB/ADP and 6:1 for DODAB/ATP. These differences may be attributed to the different anion charges of AMP, ADP and ATP. The results demonstrated that Ribonucleotides combined with DODAB vesicles with the electrostatic attraction in the complexation of DODAB and Ribonucleotides. Transmission electron microscopic results revealed the different extents of aggregation of cationic vesicles in the complexation process of Ribonucleotides with cationic lipid. The variation dependence of ζ-potentials or electrophoretic mobilities on vesicle size was also different. The ζ-potentials and electrophoretic mobilities of the DODAB vesicles (0.01 and 0.02 mM) gradually decreased when the Ribonucleotide concentration increased. However, the mean diameters of the DODAB vesicles (0.1 and 0.5 mM) gradually increased when the Ribonucleotide concentration increased.
-
Interaction of cationic vesicle with Ribonucleotides (AMP, ADP, and ATP) and physicochemical characterization of DODAB/Ribonucleotides complexes.
Biophysical chemistry, 2006Co-Authors: Shuhua LiuAbstract:The interaction between Ribonucleotides (AMP, ADP, and ATP) and cationic vesicles prepared from dioctadecyldimethylammonium bromide (DODAB) were investigated in detail. The physicochemical properties of Ribonucleotides/cationic lipid complexes were present. Gel exclusion-UV spectroscopic results showed that all the charge ratios of DODAB/Ribonucleotides (AMP, ADP, and ATP) are 2:1 when the maximal Ribonucleotides were adsorbed onto DODAB, while the molar ratios were different, e.g., 2:1 for DODAB/AMP, 4:1 for DODAB/ADP and 6:1 for DODAB/ATP. These differences may be attributed to the different anion charges of AMP, ADP and ATP. The results demonstrated that Ribonucleotides combined with DODAB vesicles with the electrostatic attraction in the complexation of DODAB and Ribonucleotides. Transmission electron microscopic results revealed the different extents of aggregation of cationic vesicles in the complexation process of Ribonucleotides with cationic lipid. The variation dependence of zeta-potentials or electrophoretic mobilities on vesicle size was also different. The zeta-potentials and electrophoretic mobilities of the DODAB vesicles (0.01 and 0.02 mM) gradually decreased when the Ribonucleotide concentration increased. However, the mean diameters of the DODAB vesicles (0.1 and 0.5 mM) gradually increased when the Ribonucleotide concentration increased.
-
Interaction of cationic vesicle with Ribonucleotides (AMP, ADP, and ATP) and physicochemical characterization of DODAB/Ribonucleotides complexes
Biophysical Chemistry, 2006Co-Authors: Shuhua LiuAbstract:Abstract The interaction between Ribonucleotides (AMP, ADP, and ATP) and cationic vesicles prepared from dioctadecyldimethylammonium bromide (DODAB) were investigated in detail. The physicochemical properties of Ribonucleotides/cationic lipid complexes were present. Gel exclusion-UV spectroscopic results showed that all the charge ratios of DODAB/Ribonucleotides (AMP, ADP, and ATP) are 2:1 when the maximal Ribonucleotides were adsorbed onto DODAB, while the molar ratios were different, e.g., 2:1 for DODAB/AMP, 4:1 for DODAB/ADP and 6:1 for DODAB/ATP. These differences may be attributed to the different anion charges of AMP, ADP and ATP. The results demonstrated that Ribonucleotides combined with DODAB vesicles with the electrostatic attraction in the complexation of DODAB and Ribonucleotides. Transmission electron microscopic results revealed the different extents of aggregation of cationic vesicles in the complexation process of Ribonucleotides with cationic lipid. The variation dependence of ζ-potentials or electrophoretic mobilities on vesicle size was also different. The ζ-potentials and electrophoretic mobilities of the DODAB vesicles (0.01 and 0.02 mM) gradually decreased when the Ribonucleotide concentration increased. However, the mean diameters of the DODAB vesicles (0.1 and 0.5 mM) gradually increased when the Ribonucleotide concentration increased.
