Related Experiment Video
Updated: Feb 19, 2026

Chemical Modification of the Tryptophan Residue in a Recombinant Ca2+-ATPase N-domain for Studying Tryptophan-ANS FRET
Published on: October 9, 2021
Position-Specific contribution of interface tryptophans on membrane protein energetics
Deepti Chaturvedi1, Radhakrishnan Mahalakshmi1
1Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal 462066, India.
Tryptophan residues in the membrane protein OmpX influence folding and stability. Substituting specific tryptophans with tyrosine or phenylalanine altered barrel assembly speed and thermodynamic stability, showing position-specific effects.
Area of Science:
- Biochemistry
- Structural Biology
- Membrane Protein Dynamics
Background:
- Interface tryptophans are crucial for membrane protein folding and stability.
- Escherichia coli OmpX has two unique interface tryptophans: Trp76 (solvent-exposed) and Trp140 (lipid-solvated).
Purpose of the Study:
- To investigate the necessity of tryptophan for OmpX folding and stability.
- To determine the effects of aromatic amino acid substitutions on OmpX folding and stability.
Main Methods:
- Spectroscopic measurements were employed to analyze OmpX mutants.
- OmpX variants with tryptophan, tyrosine, and phenylalanine substitutions were studied.
Main Results:
- The W76→Y mutation accelerated OmpX barrel assembly over 1.5-fold and increased stability by ~0.4 kcal/mol.
- Mutations at W140 (W140→F/Y) decreased OmpX thermodynamic stability by ~0.4 kcal/mol without impacting folding kinetics.
Conclusions:
- The stabilizing role of tryptophan at membrane interfaces is specific to its position and local environment.
- The thermodynamic contributions of interface residues should be interpreted cautiously.
More Related Videos
09:31PCR Mutagenesis, Cloning, Expression, Fast Protein Purification Protocols and Crystallization of the Wild Type and Mutant Forms of Tryptophan Synthase
Published on: September 26, 2020
10:09Thermodynamics of Membrane Protein Folding Measured by Fluorescence Spectroscopy
Published on: April 28, 2011
Related Concept Videos
Protein-protein Interfaces
Protein-Protein Interfaces
Protein Transport into the Inner Mitochondrial Membrane
Transport of mitochondrial precursors across the TIM23 channel is driven by...
Single-pass Transmembrane Proteins
The Significance of Membrane Transport
Transporters facilitate either an active or passive movement of solutes. They can allow a single-molecule transport down its...
Membrane Asymmetry Regulating Transporters
Flippase
Eukaryotic flippases are type-IV P-type ATPases or P4-ATPases belonging to P-type ATPase family proteins that are membrane-bound pumps involved in the ATP-mediated transport of ions and molecules across the membrane. Flippases flip specific phospholipids from the outer to the inner leaflet of a membrane. All P4-ATPases have one...