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Updated: May 6, 2026
07:42
On-Chip Crystallization and Large-Scale Serial Diffraction at Room Temperature
Published on: March 11, 2022
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Structural insights into urocanate reductase using room-temperature X-ray crystallography
Swati Aggarwal1, Nitisha Gurav2, Esko Oksanen1
1European Spallation Source ERIC (ESS), 221 00 Lund, Sweden.
Summary
Urocanate reductase (UrdA) enzyme dynamics were studied using X-ray crystallography. Room-temperature data revealed cryocooling effects on the Arg411 residue, crucial for enzyme function.
Area of Science:
- Biochemistry
- Structural Biology
- Enzymology
Background:
- Urocanate reductase (UrdA) is a bacterial enzyme catalyzing the conversion of urocanic acid to imidazole propionate.
- The enzyme's active site features a catalytic residue, Arg411, which exhibits significant conformational changes between substrate-bound and product-bound states.
- Previous studies primarily utilized cryogenic conditions, potentially masking dynamic aspects of the enzyme's active site.
Purpose of the Study:
- To investigate the conformational dynamics of Urocanate reductase (UrdA) at room temperature.
- To understand the influence of cryocooling on the enzyme's active site structure, particularly the Arg411 residue.
- To explore the role of phosphate ions in stabilizing UrdA complexes and influencing Arg411 conformation.
Main Methods:
- X-ray crystallography was employed to collect data at both room temperature and cryogenic conditions.
- Analysis of X-ray datasets focused on the occupancy distribution and conformational states of the Arg411 residue.
- Biochemical assays were used to assess the stabilizing effect of phosphate ions on substrate complexes.
Main Results:
- Room-temperature X-ray data demonstrated that crystal cryocooling impacts the occupancy distribution of the catalytic Arg411 residue.
- Phosphate ions were shown to stabilize the substrate complex of UrdA.
- Phosphate ions can influence and bias the conformation of Arg411.
- Distinct conformational states of the UrdA active site were observed at room temperature versus cryogenic conditions.
Conclusions:
- Collecting X-ray data at both room temperature and cryogenic temperatures is essential for a comprehensive understanding of UrdA's dynamic active site.
- Cryocooling can alter the observed conformational landscape of enzymes, necessitating room-temperature studies.
- Phosphate ions play a significant role in modulating UrdA's active site conformation and substrate binding.
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