Photocatalyst-Mediated Protein Labeling for 10 Nm Intracellular Precision
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Solution Overview
Problem
Existing methods for intracellular protein labeling, such as APEX, Air-ID, BioID, SPPLAT, EMARS, and Turbo-ID, suffer from non-specific labeling due to reactive species with long half-lives and preferential binding to particular amino acid residues, leading to skewed results, especially in identifying transiently- and weakly-interacting partners, which is problematic for targeted protein degradation (TPD).
Innovation Solution
A method involving a binding agent complex with a photocatalyst and labeling agent is introduced into cells, where the photocatalyst activates the labeling agent through energy transfer, forming a reactive intermediate with a short half-life and limited diffusion radius, enabling precise labeling of proteins within a 10 nm radius.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing enzymatic proximity labeling platforms (APEX, Air-ID, BioID, etc.) are used, then protein labeling can be achieved, but non-specific labeling occurs due to reactive species with long half-lives and preferential binding to particular amino acid residues
Solution Approach 1:
The patent introduces a photocatalyst as an intermediary between light energy and the labeling agent. The photocatalyst absorbs light and transfers energy to activate the labeling agent only in the immediate vicinity, creating a spatially restricted reactive zone that prevents non-specific labeling while maintaining high precision protein labeling capability
Solution Approach 2:
The patent changes the activation mechanism from enzymatic catalysis to photocatalytic activation. By using light as the activation source, the system achieves precise spatiotemporal control over labeling agent activation, reducing background noise and non-specific labeling while improving both precision and reliability of protein labeling
2Area of stationary object
If reactive species with long half-lives are used for labeling, then labeling can occur at greater distances, but proteins outside the immediate vicinity are labeled leading to non-specific results
Solution Approach 1:
The patent applies local quality by creating a highly localized reactive zone around the photocatalyst. The labeling agent is activated only within nanometers of the photocatalyst-protein complex, giving different regions of the cell distinctly different labeling properties - high labeling efficiency locally, zero labeling remotely - thereby achieving both controlled coverage and high spatial resolution
Solution Approach 2:
The patent uses periodic light activation to control the timing and location of labeling agent activation. By applying light pulses selectively to different cellular regions, the system achieves precise spatial control over where labeling occurs, preventing diffuse non-specific labeling while maintaining the ability to label proteins at targeted locations
3Productivity
If preferential binding to particular amino acid residues is utilized, then labeling efficiency increases for certain residues, but results become skewed and dependent on exposed surface residues
Solution Approach 1:
The patent creates a universal labeling system that is agnostic to amino acid residue type. The photocatalytically activated labeling agent reacts with various biomolecules (proteins, peptides, nucleic acids, lipids) without preference for specific residues, providing a multi-functional labeling capability that accurately represents the true protein interactome rather than skewing results toward accessible residues
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 allows for high-resolution, agnostic labeling of intracellular proteins, peptides, and nucleic acids, improving the accuracy of cellular mapping and protein-protein interaction detection, particularly in live cells.
Implementation Method 1
activating the labeling agent by transfer of energy from the catalyst complex to the reactive moiety
Implementation Method 2
a photocatalyst activates the labeling agent through energy transfer, forming a reactive intermediate
Data Source
AI summary
Embodiments of the present disclosure relate to methods, compositions, and systems for proximity-based, photoactivated labeling of molecules. Molecules may be labeled via activation of a ligated photocatalyst capable of transmitting energy to a proximal biomolecular labeling agent. Depending on the activated half-life and diffusion coefficient of the labeling agent, molecules within a particular vicinity of the ligated photocatalyst may be labeled but molecules outside the vicinity will not be labeled.