Aldehyde Capture Ligation for Amide Bond Formation
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Solution Overview
Problem
Current methods for chemoselective formation of amide bonds between unprotected peptide fragments are not general and can be inefficient, particularly with bulky amino acid residues and require specific residues like N-terminal cysteine or modified thiol groups.
Innovation Solution
The introduction of a ligation agent with a seleno ester group that facilitates rapid amide bond formation through aldehyde capture ligation (ACL), allowing for the formation of amide bonds between any carboxylic acid and amine, independent of the residue type, by leveraging the association between an aldehyde group and an amine for intramolecular reaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If native chemical ligation or auxiliary-based methods are used, then amide bond formation can be achieved, but the method requires specific residues like N-terminal cysteine or modified thiol groups, reducing generality
Solution Approach 1:
The invention changes the chemical parameter of the ligation mechanism by using aldehyde capture chemistry instead of thiol-based chemistry. This allows the method to work with any N-terminal amino acid residue, not just cysteine or thiol-containing residues, thereby improving generality while maintaining ease of manufacture
Solution Approach 2:
The aldehyde capture ligation method creates a universal approach that can ligate any two peptide fragments regardless of their N-terminal residue type. The method is multi-functional as it can be applied to all 20 standard amino acids and non-natural amino acids, making it universally applicable across different peptide synthesis scenarios
2Productivity
If conventional ligation methods are used, then amide bonds can be formed, but ligation rate and yield are inefficient with bulky amino acid residues at the ligation junction
Solution Approach 1:
The invention introduces an aldehyde intermediary that captures the amine functionality, forming a stable hemiaminal intermediate. This intermediary approach allows bulky residues to be accommodated at the ligation junction by providing a steric buffer and enabling the reaction to proceed through a well-defined intermediate state, thereby improving both ligation rate and yield with challenging residues
3Speed
If intramolecular bond formation is enforced to accelerate amide bond formation, then reaction speed increases, but the method becomes less general and requires specific functional group arrangements
Solution Approach 1:
The invention performs preliminary action by having the aldehyde group capture the amine functionality before the actual amide bond formation occurs. This pre-capture step creates a positioned intermediate that then undergoes rapid intramolecular cyclization to form the amide bond. This preliminary capture action accelerates the overall reaction while maintaining broad applicability to different peptide sequences
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
This approach enables efficient and general amide bond formation applicable to any N-terminal amino acid residue, overcoming the limitations of existing methods by allowing rapid ligation of challenging residues and synthesizing large molecules with high specificity and yield.
Implementation Method 1
reacting a compound containing an amino group with a ligation agent, the ligation agent including a seleno ester group, under conditions effective to produce an amide ligation product
Implementation Method 2
leveraging the association between an aldehyde group and an amine for intramolecular reaction
Data Source
AI summary
The present invention relates to ligation agents and their use in making an amide ligation product. Methods of making the ligation agents are also disclosed.