Visible-Light Cysteine Protein Modification for Stable Carbon–Carbon Bonds
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Solution Overview
Problem
Existing chemical modification methods for proteins, particularly in antibody-drug conjugates (ADCs), suffer from instability due to carbon-sulfur bonds that break in the bloodstream, leading to toxicity and limited application range, and lack methods that maintain amino acid residue configuration and yield.
Innovation Solution
A visible light-mediated labeling-activation-desulfurization-addition (LADA) strategy constructs carbon-carbon bonds on cysteine residues through a sulfhydryl removal and free radical addition reaction, using photocatalysis to selectively modify proteins under mild conditions, preserving chirality and avoiding side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If carbon-sulfur bonds are used to connect antibody and small molecule fragment in ADCs, then the modification can be achieved through cysteine residues, but the bonds are unstable in blood circulation and undergo reverse Michael addition reaction causing toxicity
Solution Approach 1:
The patent changes the bond type parameter from carbon-sulfur bond to carbon-carbon bond, fundamentally altering the chemical linkage between antibody and drug fragment. This parameter change resolves the instability issue in blood circulation while maintaining the ability to modify cysteine residues through photocatalytic carbon-carbon bond formation
Solution Approach 2:
The patent converts the reactivity of cysteine sulfhydryl groups, which previously led to unstable carbon-sulfur bonds, into a beneficial photocatalytic reaction site. By using visible light activation, the cysteine residue serves as a stable anchor point for carbon-carbon bond formation, transforming a potential weakness into a strong, stable linkage
2Stability of the object's composition
If free radical reactions are used to construct carbon-carbon bonds on protein side chains, then carbon-carbon bonds can be formed, but the method has limited application range and does not maintain amino acid residue configuration
Solution Approach 1:
The patent applies local quality by focusing the photocatalytic reaction specifically at cysteine residue positions within the protein structure. This localized approach maintains the unique properties of each amino acid residue while achieving carbon-carbon bond formation, thereby preserving amino acid configuration and expanding application range to various protein types
Solution Approach 2:
The patent introduces a photocatalyst as an intermediary substance that enables carbon-carbon bond formation at cysteine residues. The photocatalyst mediates the reaction between the cysteine sulfhydryl group and the electrophile, allowing carbon-carbon bond construction while maintaining amino acid configuration and expanding the method's versatility
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
The method achieves high-yield, wide-range protein modification with stable carbon-carbon bonds, enhancing plasma stability and enabling diverse functional group compatibility, suitable for ADCs and degrader-antibody conjugates.
Implementation Method 1
visible light-mediated labeling-activation-desulfurization-addition (LADA) strategy constructs carbon-carbon bonds on cysteine residues through a sulfhydryl removal and free radical addition reaction, using photocatalysis
Implementation Method 2
constructs carbon-carbon bonds on cysteine residues through a sulfhydryl removal and free radical addition reaction
Data Source
AI summary
A method for visible light-mediated chemical modification of a polypeptide or protein based on cysteine includes the following steps: allowing a cysteine residue on a cysteine-containing oligopeptide, polypeptide, or protein to undergo a reaction with an activating reagent to generate a free radical precursor in situ; and subjecting the free radical precursor to desulfurization under photocatalytic condition, and allowing the generated free radical intermediate to undergo an addition reaction with an olefin or an alkyne, such that sulfhydryl removal and carbon-carbon bond construction are achieved to produce a chemical modification product of the polypeptide and protein. The method cleverly avoids the influence on the chiral center, and thus the chirality of the amino acid residue can be retained. The method is conducive to well avoiding the occurrence of side reactions, and thus the efficiency of the entire conversion is very high.