Jun 10, 2026
Crystallisation of Enterovirus D68 3C protease
Forked from Crystallisation of Enterovirus D68 3C protease
- Peter Marples1,2,
- Charlotte Chinn1,2,
- Tracy Keates1,2,
- Milo Cooper1,2
- 1Diamond Light Source;
- 2Research Complex at Harwell
- OpenBind Consortium
Protocol Citation: Peter Marples, Charlotte Chinn, Tracy Keates, Milo Cooper 2026. Crystallisation of Enterovirus D68 3C protease. protocols.io https://dx.doi.org/10.17504/protocols.io.bp2l6o4mdlqe/v1
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
We use this protocol and it's working
Created: June 10, 2026
Last Modified: June 10, 2026
Protocol Integer ID: 318848
Keywords: crystallisation, XChem, CMD, Diamond Light Source, i04-1, Research complex at Harwell, suitable crystals for fragment screening, fragment screening, OpenBind, Open AI, OpenBind Consortium, Open Bind, Enterovirus, D68, 3C, Enterovirus D68, Enterovirus D68 3C, D68 3C , enterovirus d68 3c protease the development, enterovirus d68 3c protease, pathogen enterovirus d68, emerging pathogen enterovirus d68, d68 3c prob crystal, spectrum antiviral, antiviral drug, 3c protease of ev, essential role in the viral life cycle, 3c protease, viral life cycle, d68, crystallisation, throughput crystallographic
Funders Acknowledgements:
National Institutes of Health/National Institute Of Allergy and Infectious Diseases (NIH/NIAID)
Grant ID: Grant ID: U19AI171399
UK Department of Science, Innovation and Technology
Grant ID: G2-SCH-2025-06-16537
Disclaimer
The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Acknowledgements:
Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot OX11 0QX, UK
Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot OX11 0FA, UK
Oxford Lab Technologies crystal shifter https://doi.org/10.1107/S2059798320014114
Abstract
The development of effective broad-spectrum antivirals forms an important part of preparing for future pandemics. A cause for concern is the currently emerging pathogen Enterovirus D68 (EV-D68) which primarily spreads through respiratory routes causing mostly mild to severe respiratory illness but, in severe cases, acute flaccid myelitis. The 3C protease of EV-D68 is a potential target for the development of antiviral drugs due to its essential role in the viral life cycle and high sequence conservation. This protocol was used to grow D68 3C ProB crystals that were applied high-throughput crystallographic follow up compound screening on D68 3C.
Materials
SwissCI 3 lens crystallization plates https://swissci.com/product/3-lens-crystallisation-plate/ Codes:
Midi: UVXPO-3LENS 3W96T-PS 3W96T-UVP
1 Molarity (M) Tris adjusted to 7.8 with NaOH, Molecular Dimensions, Catalog # MD2-027-PH 7.8
1 Molarity (M) Ammonium acetate, Molecular Dimensions, Catalog # MD2-002-PH
50% w/v PEG 3350, Molecular Dimensions, Catalog # MD2-250-9
Purified D683C protein (35 mg/mL ) in 10 millimolar (mM) HEPES, 7.5 , 0.5 Molarity (M) NaCl, 5% glycerol, 0.5 millimolar (mM) TCEP
Protocol materials
Enterovirus D68 (EV-D68) strain EV-D68 STL 2014 12 3C protease.addgeneCatalog #228644
Safety warnings
Follow all handling warning for the chemicals used in the crystalllisation screen composition.
Enterovirus D68 3C protease expression and purification
The protein used for crystallisation was expressed and purified using the following protocol.Enterovirus D68 (EV-D68) strain EV-D68 STL 2014 12 3C protease.addgeneCatalog #228644
Protocol
CREATED BY
korvus.wang
Equipment needed
Formulatrix Rock Imager (or incubator of choice)
Equipment
Mosquito HV
NAME
High Volume 16-Channel Robotic Liquid Handler
TYPE
SPT LabTech
BRAND
3097-01057
SKU
LINK
P100 8 multi-channel pipette
Crystallisation experiment
1d
1: 110 000 dilution Sample seeds
Protein and buffer requirements:
14.4 µL 35 mg/mL Sample
2.88 mL Crystallisation screen
7.2 µL seeds, dilution 1:1 000 000
ccCrystallisation screen composition:
0.1 Molarity (M) Tris 7.8
0.2 Molarity (M) Ammonium acetate
26% w/v PEG 3350
Stock solutions used:
1 Molarity (M) Tris adjusted to 7.8 with NaOH
1 Molarity (M) Ammonium acetate
50% w/v PEG 3350
Note
The crystallisation screen can be stored in a duran bottle or aliquoted into 96 deep well block for easy dispensing into SwissCI 3 lens plates.
For long term storage keep the crystallisation screen in the fridge at 4°C.
Dispense 30 µL Crystallisation screen into SwissCI 3 lens plate reservoir wells using a 100 µl multi-channel pipette.
Dispense 75 nL 35 mg/mL Sample to each lens using the SPT mosquito.
Dispense 75 nL Crystallisation screen to each lens using the SPT mosquito.
Dispense 25 nL Seeds to each lens using the SPT mosquito.
Drop ratio: 3:3:1
Final drop volume: 175 nl
Incubate at 20 °C for 24:00:00 h in Formulatrix Rock Imager.
Imaging Schedule: The first images are taken after 12 h and the imaging schedule follows a Fibonacci sequence of days for further collections.
1d
Expected result
Crystals typically appear after 24 hours and reach their maximum size after ~24 h with some precipitation often remaining.
Morphology: small shards.
Size: ~40 μm in length and ~40 μm in width, depth of the crystals is ~20 μm, giving a
glass shard appearance
Average resolution: 1.5 Å
Space group: P21
Unit cell: 39.7 Å, 105 Å, 43.5 Å
90.00°, 110.00°, 90.00°
An example of a drop containing D68 3C protease crystals.
Data collection at Synchrotron
Diamond Light Source
Unattended Data Collection (UDC)
Data Collection Temperature: 100K
Detector: DECTRIS EIGER2 X 9M
Beamline: I04-1
Wavelength: 0.9212 Å
Resolution (Å): 1.62
Beam Size (μm): 60 X 50
Number of images: 3600
Oscillation: 0.10°
Exposure (s): 0.0020
Transmission (%): 100
Flux (ph/s): 9.50e+11
Protocol references
Crystallographic fragment screen of Enterovirus D68 3C protease and iterative design of lead-like compounds using structure-guided expansions, https://doi.org/10.1101/2024.04.29.591650