Oligonucleotide Terminal Phosphate Derivatives for siRNA Stability
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Solution Overview
Problem
The 5′-terminal monophosphate group of siRNA is prone to hydrolysis by phosphatases, affecting the stability and efficacy of siRNA in targeting mRNA.
Innovation Solution
Development of monophosphate derivatives as 3′ or 5′-terminal nucleotides in siRNA strands to enhance stability against phosphatase-mediated hydrolysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a 5′-terminal monophosphate group is used in siRNA, then RISC recognition and mRNA cleavage activity are improved, but stability against phosphatase hydrolysis deteriorates
Solution Approach 1:
The patent modifies the chemical structure of the 5′-terminal monophosphate group by changing the ester bond type from ordinary phosphodiester to phosphotriester or phosphorothioate. This parameter change in the chemical bonding structure maintains the necessary H-bond interaction with Ago2 for RISC recognition while providing resistance to phosphatase hydrolysis, thus resolving the contradiction between functional activity and stability.
Solution Approach 2:
The invention creates a composite terminal group structure combining phosphorus with sulfur or nitrogen atoms (phosphorothioate or phosphoramide derivatives). This composite chemical structure integrates the functional properties of the monophosphate group with the stability properties of sulfur-containing or nitrogen-containing bonds, simultaneously achieving RISC recognition and phosphatase resistance.
2Stability of the object's composition
If the 5′-terminal monophosphate group is modified to enhance stability, then resistance to phosphatase hydrolysis is improved, but H-bond interaction with Ago2 may be compromised
Solution Approach 1:
The patent applies local quality modification by making only the terminal phosphate group compositionally different (phosphotriester or phosphorothioate) while keeping the rest of the siRNA sequence and structure unchanged. This localized chemical modification at the 5′-terminal position provides phosphatase resistance without affecting the overall H-bonding capability required for Ago2 recognition, as the modification is confined to the terminal region rather than the entire molecule.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Stabilizes the 5′-terminal monophosphate of siRNA, ensuring accurate RISC recognition and precise mRNA cleavage.
Implementation Method 1
The 5′-terminal monophosphate of the guide strand in siRNA has an H-bond interaction with Ago2, thereby ensuring accurate positioning and precise cleavage of the target mRNA
Implementation Method 2
Since the 5′-terminal monophosphate group could be easily hydrolyzed by phosphatases in vivo, the siRNA's cleavage activity on the target mRNA is dependent on the stability of the 5′-terminal monophosphate of guide strand
Data Source
AI summary
The present invention provides a nucleotide derivative that stabilizes the terminal monophosphate of an oligonucleotide and oligonucleotides comprising the derivative. This monophosphate derivative according to the invention can be used to improve the targeted gene silencing efficiency of oligonucleotide drugs and has broad application prospects for drug research and development.