Search for: nucleotide
0.008 seconds
Total 35 records

    Stabilities and isomeric equilibria in aqueous solution of monomeric metal ion complexes of adenosine 5′-diphosphate (ADP3-) in comparison with those of adenosine 5′-monophosphate (AMP2-)

    , Article Chemistry - A European Journal ; Volume 9, Issue 4 , 2003 , Pages 881-892 ; 09476539 (ISSN) Bianchi, E. M ; Sajadi, S. A. A ; Song, B ; Sigel, H ; Sharif University of Technology
    Under experimental conditions in which the self-association of the adenine phosphates (AP), that is, of adenosine 5′-monophosphate (AMP2-) and adenosine 5′-diphosphate (ADP3-), is negligible, potentiometric pH titrations were carried out to determine the stabilities of the M(H;AP) and M(AP) complexes where M2+=Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, or Cd2+ (25°C; I = 0.1m, NaNO3). It is concluded that in the M(H;AMP)+ species M2+ is bound at the adenine moiety and in the M(H;ADP) complexes at the diphosphate unit; however, the proton resides in both types of monoprotonated complexes at the phosphate residue. The stabilities of nearly all the M(AMP) and M(ADP)- complexes are... 

    Two new methods for DNA splice site prediction based on neuro-fuzzy network and clustering

    , Article Neural Computing and Applications ; Volume 23, Issue SUPPL1 , 2013 , Pages 407-414 ; 09410643 (ISSN) Moghimi, F ; Manzuri Shalmani, M. T ; Khaki Sedigh, A ; Kia, M ; Sharif University of Technology
    Nowadays, genetic disorders, like cancer and birth defects, are a great threat to human life. Since the first noticing of these types of diseases, many efforts have been made and researches performed in order to recognize them and find a cure for them. These disorders affect genes and they appear as abnormal traits in a genetic organism. In order to recognize abnormal genes, we need to predict splice sites in a DNA signal; then, we can process the genetic codes between two continuous splice sites and analyze the trait that it represents. In addition to abnormal genes and their consequent disorders, we can also identify other normal human traits like physical and mental features. So the... 

    F.C.A: designing a fuzzy clustering algorithm for haplotype assembly

    , Article IEEE International Conference on Fuzzy Systems, 20 August 2009 through 24 August 2009 ; 2009 , Pages 1741-1744 ; 10987584 (ISSN) ; 9781424435975 (ISBN) Moeinzadeh, M. H ; Asgarian, E ; Noori, M. M ; Sadeghi, M ; Sharifian R., S ; Sharif University of Technology
    Reconstructing haplotype in MEC (Minimum Error Correction) model is an important clustering problem which focuses on inferring two haplotypes from SNP fragments (Single Nucleotide Polymorphism) containing gaps and errors. Mutated form of human genome is responsible for genetic diseases which mostly occur in SNP sites. In this paper, a fuzzy clustering approach is performed for haplotype reconstruction or haplotype assembly from a given sample Single Nucleotide Polymorphism (SNP). In the best previous approach based on reconstruction rate (Wang 2007[2]), all SNP-fragments are considered with equal values. In our proposed method the value of the fragments are based on the degree of membership... 

    Elastic properties of actin assemblies in different states of nucleotide binding

    , Article Cellular and Molecular Bioengineering ; Volume 5, Issue 1 , 2012 , Pages 1-13 ; 18655025 (ISSN) Ghodsi, H ; Kazemi, M. T ; Sharif University of Technology
    In this paper, the elastic properties of monomeric actin (G-actin) and the trimer nucleus (G-actin trimer) in different states of nucleotide binding are estimated using steered molecular dynamic (SMD) simulations. Three nucleotide binding states are considered: ADP- and ATP-bound actin and nucleotide-free actin assemblies. Our results show that nucleotide binding and the corresponding changes in structure have significant effects on the mechanical behaviors of actin assemblies. Simulations reveal that the deformation behavior of G-actin monomers is generally elastic up to engineering strains of 16 and 40% in the tension and shear tests, respectively. In addition, the G-actin trimers react... 

    Identification of the Set of Single Nucleotide Variants in Genome Responsible for the Differentiation of Expression of Genes

    , M.Sc. Thesis Sharif University of Technology Khatami, Mahshid (Author) ; Rabiee, Hamid Reza (Supervisor) ; Beigi, Hamid (Supervisor)
    Single nucleotide polymorphs, There are changes caused by a mutation in a nucleotide in the Dena sequence. Mononucleotide polymorphisms are the most common type of genetic variation. Some of these changes have little or no effect on cells, while others cause significant changes in the expression of cell genes that can lead to disease or resistance to certain diseases. Because of the importance of these changes and their effect on cell function, the relationships between these changes are also important. Over the past decade, thousands of single disease-related mononucleotide polymorphisms have been identified in genome-related studies. Studies in this field have shown that the expression of... 

    Study of the Affecting Factors on the Stability of G-Quadruplex Structures

    , Ph.D. Dissertation Sharif University of Technology Fadaei, Elham (Author) ; Tafazzoli, Mohsen (Supervisor)
    We used spectroscopic techniques to study self-assembled structures based on nucleobases like G-quadruplexes and macrocycles. Also we used DOSY NMR technique to study hydrogen bonding network in alcohol solutions. First part of our results indicate thermodynamic stability and slow kinetic of G-quadruplexes in apolar aromatic solvents like toluene. Also our results show easy monitoring of formation of each K+ or Na+ complex by NMR, due to the low solubility of alkaline metal salts in apolar media and possibility to stop at any given time in order to control G-quadruplex yield. When combined with suitable functional units, these valuable attributes may be used for the noncovalent synthesis of... 

    Nucleoside Structure using Ab-Initio Computational Methods

    , M.Sc. Thesis Sharif University of Technology Chashmniam, Saeed (Author) ; Tafazzoli, Mohsen (Supervisor)
    The spin – spin coupling constants have been calculated by the Gaussian 2009 program in order to study the nucleosides conformation. To study the effect of solvent, the calculations were performed in four solvent including water, DMSO, chloroform and Carbon tetrachloride.
    Also, the comparison is done on two computing methods including DFT (B3LYP) and HF using 6-311++g** and 6-311g basis set.One bonding (1JC-H), two bonding (2JN-H, 2JC-H) and three bonging coupling constants (3JC-H) have been calculated for unpaired adenosine, thymidine and uridine molecules.Formation of intra-molecular hydrogen bond and electron pair repulsion, respectively, makes the compounds stable and unstable.... 

    Comparative Analysis of Haplotype Assembly Algorithms to Identify and Propose Optimal Methods

    , M.Sc. Thesis Sharif University of Technology Bagher, Melina (Author) ; Jahed, Mehran (Supervisor) ; Hossein Khalaj, Babak (Supervisor)
    Humans, as a diploid species, have two nucleotide sequences of homologous chromosomes in their genomes, where one set is inherited from the mother, and the other comes from the father. The Single Individual Haplotype assembly problem (SIH) refers to the reconstruction of these two distinct nucleotide sequences of a chromosome from the sequencing reads, and it is currently considered one of the most important issues in the field of computational genomics, which plays an essential role in solving various genetic and medical problems.Nowadays direct experimental methods are not welcomed due to their high cost, and labor intensity, and are limited to certain regions of the genome, therefore,... 

    OmpF, a nucleotide-sensing nanoprobe, computational evaluation of single channel activities

    , Article Physica A: Statistical Mechanics and its Applications ; Volume 457 , 2016 , Pages 215-224 ; 03784371 (ISSN) Haji Abdolvahab, R ; Mobasheri, H ; Nikouee, A ; Ejtehadi, M. R ; Sharif University of Technology
    Elsevier B.V  2016
    The results of highthroughput practical single channel experiments should be formulated and validated by signal analysis approaches to increase the recognition precision of translocating molecules. For this purpose, the activities of the single nano-pore forming protein, OmpF, in the presence of nucleotides were recorded in real time by the voltage clamp technique and used as a means for nucleotide recognition. The results were analyzed based on the permutation entropy of current Time Series (TS), fractality, autocorrelation, structure function, spectral density, and peak fraction to recognize each nucleotide, based on its signature effect on the conductance, gating frequency and voltage... 

    Solving MEC and MEC/GI problem models, using information fusion and multiple classifiers

    , Article Innovations'07: 4th International Conference on Innovations in Information Technology, IIT, Dubai, 18 November 2007 through 20 November 2007 ; 2007 , Pages 397-401 ; 9781424418411 (ISBN) Asgarian, E ; Moeinzadeh, M. H ; Mohammadzadeht, J ; Ghazinezhad, A ; Habibi, J ; Najafi Ardabili, A ; Sharif University of Technology
    IEEE Computer Society  2007
    Mutations in Single Nucleotide Polymorphisms (SNPs - different variant positions (1%) from human genomes) are responsible for some genetic diseases. As a consequence, obtaining all SNPs from human populations is one of the primary goals of recent studies in human genomics. Two sequences of mentioned SNPs in diploid human organisms are called haplotypes. In this paper, we study haplotype reconstruction from SNP-fragments with and without genotype information, problems. Designing serial and parallel classifiers was center of our research. Genetic algorithm and K-means were two components of our approaches. This combination helps us to cover the single classifier's weaknesses. ©2008 IEEE  

    Atomic scale interactions between RNA and DNA aptamers with the TNF- α protein

    , Article BioMed Research International ; Volume 2021 , 2021 ; 23146133 (ISSN) Asadzadeh, H ; Moosavi, A ; Alexandrakis, G ; Mofrad, M. R. K ; Sharif University of Technology
    Hindawi Limited  2021
    Interest in the design and manufacture of RNA and DNA aptamers as apta-biosensors for the early diagnosis of blood infections and other inflammatory conditions has increased considerably in recent years. The practical utility of these aptamers depends on the detailed knowledge about the putative interactions with their target proteins. Therefore, understanding the aptamer-protein interactions at the atomic scale can offer significant insights into the optimal apta-biosensor design. In this study, we consider one RNA and one DNA aptamer that were previously used as apta-biosensors for detecting the infection biomarker protein TNF-α, as an example of a novel computational workflow for... 

    Colorimetric assay for exon 7 SMN1/SMN2 single nucleotide polymorphism using gold nanoprobes

    , Article BioImpacts ; Volume 3, Issue 4 , 2013 , Pages 185-194 ; 22285652 (ISSN) Ahmadpour Yazdi, H ; Hormozi Nezhad, M. R ; Abadi, A ; Sanati, M. H ; Kazemi, B ; Sharif University of Technology
    Introduction: Proximal spinal muscular atrophy (SMA) is one of the most significant neurodegenerative diseases amongst the autosomal-recessive genetic disorders which is caused by the absence of protein survival of motor neuron (SMN). A critical nucleotide difference in SMN2 compared to SMN1 gene leads to an inefficient protein. Hence, homozygous lack of SMN1 provides a progressive disease. Due to the high prevalence, up to now, several molecular diagnostic methods have been used which most of them are lengthy, expensive, and laborious. Methods: In the present study, we exploited a gold nanoprobe-based method for semi-quantitative SMN1 gene dosage analysis compared to SMN2. The assay was... 

    A quantum mechanical approach towards the calculation of transition probabilities between DNA codons

    , Article BioSystems ; Volume 184 , 2019 ; 03032647 (ISSN) Ghasemi, F ; Shafiee, A ; Sharif University of Technology
    Elsevier Ireland Ltd  2019
    The role of quantum tunneling in altering the structure of nucleotides to each other and causing a mutational event in DNA has been a topic of debate for years. Here, we introduce a new quantum mechanical approach for analyzing a typical point-mutation in DNA strands. Assuming each codon as a base state, a superposition of codon states could provide a physical description for a set of codons encoding the same amino acid and there are transition amplitudes between them. We choose the amino acids Phe and Ile as our understudy bio-systems which are encoded by two and three codons, respectively. We treat them as large quantum systems and use double- and triple-well potential models to study the... 

    Spectrophotometric studies of molecular complex formation between water-soluble cobalt(II) Schiff base complex and nucleotides in mixed solvent systems

    , Article Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy ; Volume 61, Issue 13-14 , 2005 , Pages 3061-3065 ; 13861425 (ISSN) Boghaei, D. M ; Gharagozlou, M ; Sharif University of Technology
    The formation constants for 1:1 molecular complex formation between water-soluble cobalt(II) tetradentate Schiff base complex, disodium[{bis(4- methoxy-5-sulfo-salicylaldehyde)-4,5-dimethyl-o-phenylenediiminato}cobalt(II)], Na2[Co(SO3-4-meosal-4,5-dmophen)], and nucleotides, adenosine-5′-triphosphate (ATP) and cytidine-5′-triphosphate (CTP), in mixed solvent systems of ethanol and water with different volume fractions of ethanol and water have been determined spectrophotometrically at constant ionic strength (I = 0.2 mol dm-3 NaClO4) and temperature 278 K. Trends in the values of formation constants according to the volume fractions of ethanol and water in ethanol and water mixed solvent... 

    Toward single-DNA electrochemical biosensing by graphene nanowalls

    , Article ACS Nano ; Volume 6, Issue 4 , March , 2012 , Pages 2904-2916 ; 19360851 (ISSN) Akhavan, O ; Ghaderi, E ; Rahighi, R ; Sharif University of Technology
    Graphene oxide nanowalls with extremely sharp edges and preferred vertical orientation were deposited on a graphite electrode by using electrophoretic deposition in an Mg 2+-GO electrolyte. Using differential pulse voltammetry (DPV), reduced graphene nanowalls (RGNWs) were applied for the first time, in developing an ultra-high-resolution electrochemical biosensor for detection of the four bases of DNA (G, A, T, and C) by monitoring the oxidation signals of the individual nucleotide bases. The extremely enhanced electrochemical reactivity of the four free bases of DNA, single-stranded DNA, and double-stranded DNA (dsDNA) at the surface of the RGNW electrode was compared to electrochemical... 

    Application of single-nucleotide polymorphisms in the diagnosis of autism spectrum disorders: a preliminary study with artificial neural networks

    , Article Journal of Molecular Neuroscience ; Volume 68, Issue 4 , 2019 , Pages 515-521 ; 08958696 (ISSN) Ghafouri Fard, S ; Taheri, M ; Omrani, M. D ; Daaee, A ; Mohammad Rahimi, H ; Kazazi, H ; Sharif University of Technology
    Springer New York LLC  2019
    Autism spectrum disorder (ASD) includes different neurodevelopmental disorders characterized by deficits in social communication, and restricted, repetitive patterns of behavior, interests or activities. Based on the importance of early diagnosis for effective therapeutic intervention, several strategies have been employed for detection of the disorder. The artificial neural network (ANN) as a type of machine learning method is a common strategy. In the current study, we extracted genomic data for 487 ASD patients and 455 healthy individuals. All individuals were genotyped in certain single-nucleotide polymorphisms within retinoic acid-related orphan receptor alpha (RORA), gamma-aminobutyric... 

    Dependency of codon usage on protein sequence patterns: A statistical study

    , Article Theoretical Biology and Medical Modelling ; Vol. 11, issue. 1 , 2014 ; ISSN: 17424682 Foroughmand-Araabi, M. H ; Goliaei, B ; Alishahi, K ; Sadeghi, M ; Sharif University of Technology
    Background: Codon degeneracy and codon usage by organisms is an interesting and challenging problem. Researchers demonstrated the relation between codon usage and various functions or properties of genes and proteins, such as gene regulation, translation rate, translation efficiency, mRNA stability, splicing, and protein domains. Researchers usually represent segments of proteins responsible for specific functions or structures in a family of proteins as sequence patterns or motifs. We asked the question if organisms use the same codons in pattern segments as compared to the rest of the sequence. Methods. We used the likelihood ratio test, Pearson's chi-squared test, and mutual information... 

    Solving MEC model of haplotype reconstruction using information fusion, single greedy and parallel clustering approaches

    , Article 6th IEEE/ACS International Conference on Computer Systems and Applications, AICCSA 2008, Doha, 31 March 2008 through 4 April 2008 ; 2008 , Pages 15-19 ; 9781424419685 (ISBN) Asgarian, E ; Moeinzadeh, M. H ; Sharifian-R, S ; Najafi-A, A ; Ramezani, A ; Habibi, J ; Mohammadzadeh, J ; Sharif University of Technology
    Haplotype information has become increasingly important in analyzing fine-scale molecular genetics data, Due to the mutated form in human genome; SNPs (Single Nucleotide Polymorphism) are responsible for some genetic diseases. As a consequence, obtaining all SNPs from human populations is one of the primary goals of studies in human genomics. In this paper, a data fusion method based on multiple parallel classifiers for reconstruction of haplotypes from a given sample Single Nucleotide Polymorphism (SNP) is proposed. First, we design a single greedy algorithm for solving haplotype reconstructions. [2] is used as an efficient approach to be combined with first classification method. The... 

    Rigid-body molecular dynamics of DNA inside a nucleosome

    , Article European Physical Journal E ; Volume 36, Issue 3 , March , 2013 ; 12928941 (ISSN) Fathizadeh, A ; Berdy Besya, A ; Ejtehadi, M. R ; Schiessel, H ; Sharif University of Technology
    The majority of eukaryotic DNA, about three quarter, is wrapped around histone proteins forming so-called nucleosomes. To study nucleosomal DNA we introduce a coarse-grained molecular dynamics model based on sequence-dependent harmonic rigid base pair step parameters of DNA and nucleosomal binding sites. Mixed parametrization based on all-atom molecular dynamics and crystallographic data of protein-DNA structures is used for the base pair step parameters. The binding site parameters are adjusted by experimental B-factor values of the nucleosome crystal structure. The model is then used to determine the energy cost for placing a twist defect into the nucleosomal DNA which allows us to use... 

    Specific targeting delivery to MUC1 overexpressing tumors by albumin-chitosan nanoparticles conjugated to DNA aptamer

    , Article International Journal of Pharmaceutics ; Volume 515, Issue 1-2 , 2016 , Pages 607-615 ; 03785173 (ISSN) Esfandyari Manesh, M ; Mohammadi, A ; Atyabi, F ; Nabavi, S. M ; Ebrahimi, S. M ; Shahmoradi, E ; Shiri Varnamkhasti, B ; Ghahremani, M. H ; Dinarvand, R ; Sharif University of Technology
    Elsevier B.V  2016
    Chitosan-coated human serum albumin nanoparticles were functionalized by MUC1 aptamer to obtain a selective drug carrier toward cancers overexpressing MUC1. The negative charges of albumin nanoparticles were shifted to positive charges by surface modification with chitosan, and MUC1 was conjugated through an acrylate spacer. The cytotoxicity of targeted nanoparticles was significantly more than non-aptamer nanoparticles, and also the chitosan-coated nanoparticles had more cytotoxic effects than the negatively charged albumin nanoparticles. The IC50 of targeted nanoparticles was 28 and 26% of free paclitaxel in MCF7 and T47D cells at 48 h, respectively. Confocal laser scanning electron...