Agarose Gel Delivery Medium for Serial Femtosecond Crystallography
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Solution Overview
Problem
Current methods for serial femtosecond crystallography require large amounts of protein for membrane protein structure determination, and existing crystal delivery media are not suitable for delivering multi-protein complexes, membrane proteins, nucleic acids, or viruses due to issues like protein denaturation and high background scattering.
Innovation Solution
A method and medium using agarose as a crystal delivery medium, mixed with crystals and a cryoprotectant, to form a stable and inert stream for serial femtosecond crystallography, which embeds crystals and maintains their integrity while reducing background scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If gas dynamic virtual nozzle liquid jet is used to deliver crystals, then crystal delivery speed is high, but protein consumption is excessive (10-100 mg)
Solution Approach 1:
The patent changes the physical state parameter of the delivery medium from liquid to gel (agarose), which fundamentally alters the flow characteristics and crystal delivery mechanism. This parameter change allows for much slower flow rates while maintaining stable delivery, thereby reducing protein consumption by two orders of magnitude compared to liquid jet methods.
Solution Approach 2:
The patent utilizes the phase transition property of agarose, which transitions from liquid to gel upon cooling. This phase transition enables the creation of a stable, controllable gel stream that can be delivered at very slow rates while maintaining crystal integrity and delivery efficiency, resolving the contradiction between delivery speed and protein consumption.
2Quantity of substance
If lipidic cubic phase is used as delivery medium, then protein consumption is reduced, but background scattering increases
Solution Approach 1:
The patent extracts and eliminates the problematic lipidic cubic phase medium, replacing it with agarose gel. This removal of the harmful medium (LCP) that causes high background scattering while maintaining the beneficial slow delivery rate achieves both low protein consumption and low background scattering simultaneously.
Solution Approach 2:
The patent introduces agarose gel as an intermediary medium that replaces the harmful LCP. This intermediary substance provides the necessary gel structure for slow delivery while being transparent and non-scattering, thus mediating between the requirements of slow delivery and low background scattering.
3Quantity of substance
If electrospinning injector is used, then protein consumption is reduced, but crystal stability is compromised due to high electric fields
Solution Approach 1:
The patent replaces the electrospinning injector's electric field-based mechanism with a purely mechanical gel extrusion system. The agarose gel stream is delivered through mechanical pressure control without any high electric fields, thereby maintaining crystal stability while achieving low protein consumption through precise control of gel flow rate.
4Speed
If GDVN liquid jet delivers crystals in mother liquor, then delivery speed is fast, but only 1 out of 10,000 crystals is probed
Solution Approach 1:
The patent changes the delivery medium from liquid to gel, which fundamentally alters the flow dynamics. The gel medium allows for extremely slow, controlled delivery rates, increasing the residence time of crystals in the beam path and significantly improving the probability of effective crystal probing while maintaining efficient data collection.
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 agarose medium reduces protein consumption by two orders of magnitude and minimizes background scattering, enabling the structure determination of challenging proteins and complexes with lower sample requirements and improved data quality.
Implementation Method 1
A crystal delivery medium based on agarose, and system and method of preparation, for serial femtosecond crystallography
Implementation Method 2
The medium comprises: crystals; agarose; a cryoprotectant; and a crystallization buffer
Implementation Method 3
In SFX, nanocrystals and/or microcrystals are delivered in a liquid (DePonte et al., 2008) or a viscous stream (Weierstall et al., 2014) into the beam path of a hard X-ray free-electron laser (XFEL). XFEL radiation is composed of femtosecond pulses typically delivered at a rate of 1-120 Hz, and diffraction patterns are obtained before the crystals are destroyed
Data Source
AI summary
A system and method for preparing a crystal delivery medium comprising agarose for serial femtosecond crystallography and uses thereof.