Origins of the enhanced affinity of RNA-protein interactions triggered by RNA phosphorodithioate backbone modification

The well-characterized interaction between the MS2 coat protein and its cognate RNA hairpin was used to evaluate changes in affinity as a result of phosphorodithioate (PS2) replacing phosphate by biolayer interferometry (BLI).

Selection of PD1/PD-L1 X-Aptamers

Selections were performed using a bead-based X-Aptamer (XA) library containing several different amino acid functional groups attached to dU at the 5-position.

X-Aptamer Selection and Validation

X-Aptamers contain combinations of chemical modifications that cannot be amplified using PCR. A unique bead-based process is required to perform selections of X-Aptamers to protein and small molecule targets.

Nano-SPRi Aptasensor for the Detection of Progesterone in Buffer.

Abstract: Progesterone is a steroid hormone that plays a central role in the female reproductive processes such as ovulation and pregnancy with possible effects on other organs as well. The measurement of progesterone levels in bodily fluids can assist in early pregnancy diagnosis and can provide insight for other reproductive functions. In this work, the…

Electrochemical aptamer scaffold biosensors for detection of botulism and ricin toxins.

Abstract: Protein toxins present considerable health risks, but detection often requires laborious analysis. Here, we developed electrochemical aptamer biosensors for ricin and botulinum neurotoxins, which display robust and specific signal at nanomolar concentrations and function in dilute serum. These biosensors may aid future efforts for the rapid diagnosis of toxins. Chem Commun (Camb) 2015, 51,…

X-aptamers: a bead-based selection method for random incorporation of druglike moieties onto next-generation aptamers for enhanced binding.

Abstract: By combining pseudorandom bead-based aptamer libraries with conjugation chemistry, we have created next-generation aptamers, X-aptamers (XAs). Several X-ligands can be added in a directed or random fashion to the aptamers to further enhance their binding affinities for the target proteins. Here we describe the addition of a drug (N-acetyl-2,3-dehydro-2-deoxyneuraminic acid), demonstrated to bind to…

Construction and selection of bead-bound combinatorial oligonucleoside phosphorothioate and phosphorodithioate aptamer libraries designed for rapid PCR-based sequencing.

Abstract: Chemically synthesized combinatorial libraries of unmodified or modified nucleic acids have not previously been used in methods to rapidly select oligonucleotides binding to target biomolecules such as proteins. Phosphorothioate oligonucleotides (S‐ODNs) or phosphorodithioate oligonucleotides (S2‐ODNs) with sulfurs replacing one or both of the non‐bridging phosphate oxygens bind to proteins more tightly than unmodified oligonucleotides…

Evoking picomolar binding in RNA by a single phosphorodithioate linkage.

Abstract: RNA aptamers are synthetic oligonucleotide-based affinity molecules that utilize unique three-dimensional structures for their affinity and specificity to a target such as a protein. They hold the promise of numerous advantages over biologically produced antibodies; however, the binding affinity and specificity of RNA aptamers are often insufficient for successful implementation in diagnostic assays or…

Crystal structure, stability and Ago2 affinity of phosphorodithioate-modified RNAs

Abstract: Small interfering RNAs (siRNAs) with phosphorodithioate modifications (PS2-RNA) possess favourable properties for use as RNAi therapeutics. Beneficial here is the combining of PS2 and 20 -O-methyl modifications (MePS2). SiRNAs with MePS2 moieties in the sense strand show promising efficacies in vitro and in vivo. Crystal structures of PS2- and MePS2- modified RNAs reveal subtle…

2′-OMe-phosphorodithioate-modified siRNAs show increased loading into the RISC complex and enhanced anti-tumour activity.

Abstract: Improving small interfering RNA (siRNA) efficacy in target cell populations remains a challenge to its clinical implementation. Here, we report a chemical modification, consisting of phosphorodithioate (PS2) and 2′-O-Methyl (2′-OMe) MePS2 on one nucleotide that significantly enhances potency and resistance to degradation for various siRNAs. We find enhanced potency stems from an unforeseen increase…




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