Halogen-Substituted Alkoxymethyl RNA for Duplex Stability
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Solution Overview
Problem
Current 2'-modified RNAs, such as 2'-O-methyl and 2'-O-methoxyethyl, face challenges in double strand-forming ability and synthesis complexity, especially when incorporating different nucleic acid bases, leading to low double strand melting temperature and limited applicability.
Innovation Solution
Introduction of a halogen atom as a substituent in the alkoxymethyl-based protective group of ribonucleosides and ribonucleotides enhances double strand-forming ability and allows for a common synthesis method regardless of the nucleic acid base, using specific halogen-substituted alkoxymethyl groups like 2-chloroethoxymethyl and 2,2-dichloroethoxymethyl.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If 2'-O-methyl modification is conducted on nucleic acid, then the Tm value is improved, but synthesis complexity increases when incorporating different nucleic acid bases
Solution Approach 1:
The patent introduces a universal protecting group structure (formula 1) that can be applied to all four nucleic acid bases (A, U, G, C) without requiring base-specific modification protocols. This single protecting group design enables uniform synthesis procedures across different bases, eliminating the need to search for appropriate manufacturing methods for each base type while maintaining the Tm value improvement benefits of 2'-O-methyl modification.
2Device complexity
If 2'-O-ethoxymethyl modification is performed, then the structure is simplified, but the double strand melting temperature Tm is lowered
Solution Approach 1:
The patent modifies the ethoxymethyl structure by introducing a halogen atom (fluorine, chlorine, bromine, or iodine) at the alpha position to create a new chemical parameter configuration. This parameter change (adding halogen substituent) fundamentally alters the thermal properties of the modification, resulting in increased Tm values while preserving the structural simplicity and ease of synthesis characteristics of the ethoxymethyl group.
3Temperature
If 2'-O-methoxyethyl modification is conducted, then the structure is stabilized, but synthesis complexity increases and double strand-forming ability decreases
Solution Approach 1:
The patent applies local quality modification by introducing a halogen atom at the specific alpha position of the methoxyethyl chain. This localized chemical modification provides targeted enhancement of double strand-forming ability through halogen bonding interactions, while the rest of the methoxyethyl structure maintains its stabilizing properties. The synthesis complexity is reduced by using a universal protecting group approach that works for all nucleic acid bases.
Data Source
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AI summary
[Problem] To provide a 2'-modified ribonucleoside or the like which has a high duplex-forming ability. [Solution] The present invention is generally based on the finding in embodiments that a modified form of a ribonucleoside or the like having an alkoxymethyl protective group can be imparted with a high duplex-forming ability by introducing, as a substituent, a halogen atom into the protective group moiety. As explained before, a modified form of RNA having an alkoxymethyl protective group has a low duplex-forming ability. A modified form of RNA having a halogen-substituted alkoxymethyl protective group, however, exhibits a high duplex-forming ability that is comparable to the duplex-forming ability of a 2'-O-methyl modified nucleic acid.