Microcrystal Ligand Analysis Using On-Grid Soaking and Electron Diffraction
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Solution Overview
Problem
Existing methods for incorporating small molecules into protein crystals, such as soaking or co-crystallization, face challenges like crystal cracking, dissolution, and inefficient diffusion, leading to weak density and difficulty in modeling ligand interactions.
Innovation Solution
A method involving on-grid soaking of small molecules onto electron microscopy grids, followed by focused ion beam milling to create microcrystals, which are then analyzed using transmission electron microscopy for structural modeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ligands are soaked into protein crystals using traditional methods, then ligand-protein interactions can be studied, but the crystals often crack or dissolve and ligand occupancy is weak
Solution Approach 1:
The patent changes the physical state and environment parameters by using cryogenic temperatures and electron microscopy conditions, which prevent crystal cracking and dissolution while enabling efficient ligand diffusion and high occupancy in the crystal lattice
Solution Approach 2:
The patent replaces traditional X-ray crystallography mechanical systems with electron microscopy-based methods, allowing for direct visualization and analysis of ligand-protein interactions in microcrystals without causing the mechanical stress that leads to cracking
2Ease of manufacture
If co-crystallization is used to incorporate ligands into protein crystals, then ligand-protein complexes can be formed, but crystallization conditions change or ligands form close contacts instead of binding to the target site
Solution Approach 1:
The patent performs preliminary action by first forming the protein crystal structure without the ligand, then introducing the ligand under controlled cryogenic conditions, ensuring the ligand binds to the correct site rather than forming incorrect close contacts
Solution Approach 2:
The patent uses cryogenic conditions as an intermediary environment that facilitates proper ligand binding by preventing premature crystallization and ensuring ligands reach their correct binding sites before the crystal lattice forms
3Productivity
If traditional soaking methods are used, then ligands can diffuse into crystals, but the process is inefficient and ligand occupancy remains weak
Solution Approach 1:
The patent changes temperature parameters to cryogenic levels, which dramatically increases ligand uptake efficiency by preventing crystal dissolution and maintaining structural integrity during the soaking process, leading to high ligand occupancy
4Measurement precision
If weak ligand density is observed in traditional methods, then structural modeling becomes difficult, but this is a consequence of poor ligand incorporation
Solution Approach 1:
The patent replaces X-ray crystallography with electron microscopy methods, which provide superior contrast and resolution for visualizing ligand density in protein crystals, eliminating the information loss that occurs in traditional methods
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 more efficient uptake and higher occupancy of small molecules in protein crystals, enabling high-resolution structural modeling and identification of binding sites, suitable for high-throughput drug discovery.
Implementation Method 1
milling the crystal having the macromolecule and the small molecule in the FIB/SEM using a focused ion beam to obtain a microcrystal
Implementation Method 2
collecting a plurality of electron diffraction patterns from the microcrystal
Data Source
AI summary
Methods of introducing a small molecule into a crystal of a macromolecule, of obtaining a microcrystal having a macromolecule and a small molecule from a crystal of the macromolecule, of determining a structural model for a complex having a macromolecule and a small molecule, of identifying a small molecule that complexes with a macromolecule, and of screening a library of small molecules for their binding to a macromolecule are disclosed.