Related Experiment Video

Updated: May 23, 2026

Thermodynamics of Membrane Protein Folding Measured by Fluorescence Spectroscopy
10:09

Thermodynamics of Membrane Protein Folding Measured by Fluorescence Spectroscopy

Published on: April 28, 2011

Conformational dynamics of the trp-cage miniprotein at its folding temperature

Anna Hałabis1, Wioletta Żmudzińska, Adam Liwo

  • 1Laboratory of Biopolymer Structure, Intercollegiate Faculty of Biotechnology, University of Gdańsk and Medical University of Gdańsk, Kładki 24, 80-922 Gdańsk, Poland.

The Journal of Physical Chemistry. B
|April 14, 2012
PubMed

Insights

The trp-cage mini-protein

Area of Science:

  • Protein folding dynamics
  • Biophysical chemistry
  • Structural biology

Background:

  • The trp-cage mini-protein's folding temperature is 311-317 K.
  • Understanding protein structure and dynamics near melting temperature is crucial.

Purpose of the Study:

  • To determine the structure and dynamics of the trp-cage mini-protein near its melting temperature.
  • To elucidate the molecular mechanisms of protein unfolding.

Main Methods:

  • Nuclear Magnetic Resonance (NMR) spectroscopy to observe spectral signals.
  • Analysis of Nuclear Overhauser Effect (NOE) signals to identify interactions.

Main Results:

  • At 305 K, Trp6-Arg16 and Trp6-Pro12 interactions are present; at 313 K, only Trp6-Arg16 remains.
  • Partial and complete melting of the N-terminal alpha-helix occurs at 305 K and 313 K, respectively.
  • Local interactions vanish rapidly, while long-range Trp6-Arg16 interactions persist until 313 K.

Conclusions:

  • Protein melting involves cooperative breaking of hydrophobic interactions and helix melting.
  • The trp-cage exhibits a diffuse native state near melting, deviating from a simple two-state folding model.

More Related Videos

Microfluidic Mixers for Studying Protein Folding12:42

Microfluidic Mixers for Studying Protein Folding

Published on: April 10, 2012

4D Imaging of Protein Aggregation in Live Cells08:59

4D Imaging of Protein Aggregation in Live Cells

Published on: April 5, 2013

Related Concept Videos

Protein Folding01:25

Protein Folding

Proteins are chains of amino acids linked together by peptide bonds. Upon synthesis, a protein folds into a three-dimensional conformation, critical to its biological function. Interactions between its constituent amino acids guide protein folding, and hence the protein structure is primarily dependent on its amino acid sequence.
Protein Structure Is Critical to Its Biological Function
Proteins perform a wide range of biological functions such as catalyzing chemical reactions, providing...
Protein Folding01:22

Protein Folding

Overview
Protein Folding01:22

Protein Folding

Overview
Molecular Chaperones and Protein Folding03:00

Molecular Chaperones and Protein Folding

The native conformation of a protein is formed by interactions between the side chains of its constituent amino acids. When the amino acids cannot form these interactions, the protein cannot fold by itself and needs chaperones. Notably, chaperones do not relay any additional information required for the folding of polypeptides; the native conformation of a protein is determined solely by its amino acid sequence. Chaperones catalyze protein folding without being a part of the folded protein.
The...
Bacterial Protein Maturation01:26

Bacterial Protein Maturation

Bacterial protein maturation is a tightly regulated process that ensures newly synthesized polypeptides achieve correct functional conformations. This maturation involves a series of modifications, folding events, and quality control steps, often assisted by specialized chaperone proteins.N-Terminal ModificationsThe maturation of bacterial polypeptides begins cotranslationally as the polypeptide exits the ribosome. The first amino acid, N-formylmethionine (fMet), is typically modified at the...
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution00:52

¹H NMR of Conformationally Flexible Molecules: Temporal Resolution

At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...