Related Experiment Videos
Crystal structure of thioltransferase at 2.2 A resolution
S K Katti1, A H Robbins, Y Yang
1Bayer Corporation, Pharmaceutical Division, West Haven, Connecticut 06516, USA.
Protein Science : a Publication of the Protein Society
|October 1, 1995
Summary
This study presents the first 3D structure of mammalian thioltransferase, revealing a conserved fold similar to other thiol-redox proteins. The active site disulfide and key residues are identified, aiding in understanding its dehydroascorbate reductase function.
Area of Science:
- Biochemistry
- Structural Biology
- X-ray Crystallography
Background:
- Thioltransferase is a protein with known thiol-redox properties and dehydroascorbate reductase activity.
- Understanding its structure is crucial for elucidating its function in biological systems.
Purpose of the Study:
- To determine the first three-dimensional (3D) structure of mammalian thioltransferase.
- To characterize the protein's fold, active site, and conserved features.
Main Methods:
- Single crystal X-ray crystallography at 2.2 Å resolution.
- Recombinant pig liver thioltransferase expressed in Escherichia coli.
- Multiple isomorphous replacement method using heavy-atom derivatives.
Main Results:
- The protein exhibits an alpha/beta structure with a central four-stranded mixed beta-sheet flanked by helices.
- The fold is conserved among related thiol-redox proteins like E. coli thioredoxin.
- The active site disulfide (Cys22-Cys25) is surface-exposed, with Cys22 having a low pKa (3.8).
- A conserved cis-peptide configuration involving Pro70 is observed near the disulfide bridge.
Conclusions:
- The determined 3D structure provides insights into the conserved nature of thiol-redox proteins.
- The structural data aligns with existing mutational data, validating the model.
- This structure serves as a foundation for further functional and mechanistic studies of thioltransferase.