Related Experiment Video
Updated: Oct 11, 2026

A Novel Saturation Mutagenesis Approach: Single Step Characterization of Regulatory Protein Binding Sites in RNA Using Phosphorothioates
Published on: August 21, 2018
Chemical modification of pyrimidine TFOs: effect on i-motif and triple helix formation
1Laboratoire de Biophysique, Muséum National d'Historie Naturelle, INSERM U201, CNRS UMR 8646, Paris, France.
Abstract:
In order to form more stable triple helical structures or to prevent their degradation in cells, oligonucleotide analogs are routinely used, either in the backbone or among the bases. The target sequence chosen for this study is a 16-base-long oligopurine-oligopyrimidine region present in the human neurotrophin 4/5 gene. Seven different chemical modifications were tested for their effect on (i) triple helix formation and (ii) i-DNA stability. i-DNA is a tetrameric structure involving hemiprotonated C x C+ base pairs, which may act as a competing structure for triplex formation, especially in the case of a cytosine-rich third strand. At acid pH, oligophosphoramidates formed the most stable triple helix, whereas oligonucleotides including 5-propynyl-dU formed a stable i-motif which precluded triplex formation. Only two candidates stabilized triple helices at neutral pH: oligonucleotides with phosphoramidate linkage and phosphodiester oligonucleotides containing 5-methyl-dC and 5-propynyl-dU.
More Related Videos
12:19Tools to Study the Role of Architectural Protein HMGB1 in the Processing of Helix Distorting, Site-specific DNA Interstrand Crosslinks
Published on: November 10, 2016
09:04Sequence-specific and Selective Recognition of Double-stranded RNAs over Single-stranded RNAs by Chemically Modified Peptide Nucleic Acids
Published on: September 21, 2017
Related Concept Videos
Transfer RNA Synthesis
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
DNA Topoisomerases
Types and Mechanism of action
Topoisomerases are divided into two main types. Type I...
Covalently Linked Protein Regulators
These groups modify specific amino acids in a protein.
Spontaneous and Induced Mutations
Pharmacogenetics of Drug Targets: β₂-Adrenergic Receptors, Apo E, Thymidylate Synthase
Allosteric Proteins-ATCase
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...