Related Experiment Video
Updated: May 9, 2026
07:22
How to Stabilize Protein: Stability Screens for Thermal Shift Assays and Nano Differential Scanning Fluorimetry in the Virus-X Project
Published on: February 11, 2019
White wine proteins: how does the pH affect their conformation at room temperature?
Marie Dufrechou1, Aude Vernhet, Pierre Roblin
1INRA, UMR1083 SPO, F-34060 Montpellier, France.
Langmuir : the ACS Journal of Surfaces and Colloids
|July 23, 2013
Summary
Wine protein stability is pH-dependent. Lower pH can destabilize certain wine proteins, like chitinases, by exposing hydrophobic sites, potentially leading to haze formation. Stable proteins, such as invertase, are unaffected.
Area of Science:
- Enology
- Protein Chemistry
- Biochemistry
Background:
- Wine proteins can aggregate and cause haze, particularly at low pH.
- Understanding protein conformational stability is crucial for wine quality.
Purpose of the Study:
- To investigate the impact of pH on the conformational stability of wine proteins.
- To identify specific wine proteins affected by pH variations.
Main Methods:
- Circular dichroism and fluorescence spectroscopy to analyze protein structure.
- Small-angle X-ray scattering (SAXS) to determine protein shape.
- Testing of four pure wine proteins (invertase, thaumatin-like, two chitinase isoforms) at pH 2.5 and 4.0.
Main Results:
- Chitinase isoforms showed partial unfolding and exposure of hydrophobic sites at low pH.
- These conformational changes destabilized the native state of chitinases.
- Stable proteins like invertase and thaumatin-like proteins were not significantly affected by pH changes.
Conclusions:
- Conformational stability of certain wine proteins, specifically chitinases, is sensitive to pH.
- pH-induced destabilization can lead to protein aggregation and potential wine haze.
- Wine protein stability varies significantly among different protein types.
Related Concept Videos
01:28Protein Denaturation
The function of proteins depends on their native three-dimensional structure, which is dictated by the amino acid sequence of the specific protein. Folding of the polypeptide chain takes place under specific conditions that energetically favor the folded conformation. In contrast, protein denaturation occurs spontaneously under unfavorable conditions that disrupt the integrity of the folded conformation. Thus, the chemical and physical environment of a protein, such as significant changes in pH...
01:25Protein 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 Structure Is Critical to Its Biological Function
Proteins perform a wide range of biological functions such as catalyzing chemical reactions, providing...
01:22Protein Folding
Overview
02:15Protein and Protein Structure
Proteins are one of the most abundant organic molecules in living systems and have the most diverse range of functions of all macromolecules. Proteins may be structural, regulatory, contractile, or protective. They may serve in transport, storage, or membranes; or they may be toxins or enzymes. Their structures, like their functions, vary greatly. They are all, however, amino acid polymers arranged in a linear sequence.
A protein's shape is critical to its function. For example, an enzyme can...
A protein's shape is critical to its function. For example, an enzyme can...
01:23Membrane Fluidity
Cell membranes are composed of phospholipids, proteins, and carbohydrates loosely attached to one another through chemical interactions. Molecules are generally able to move about in the plane of the membrane, giving the membrane its flexible nature called fluidity. Two other features of the membrane contribute to membrane fluidity: the chemical structure of the phospholipids and the presence of cholesterol in the membrane.
01:26Membrane Fluidity
Membrane fluidity is explained by the fluid mosaic model of the cell membrane, which describes the plasma membrane structure as a mosaic of components—including phospholipids, cholesterol, proteins, and carbohydrates—that gives the membrane a fluid character.
Mosaic nature of the membrane
The mosaic characteristic of the membrane helps the plasma membrane remain fluid. The integral proteins and lipids exist as separate but loosely-attached molecules in the membrane. The membrane is a relatively...
Mosaic nature of the membrane
The mosaic characteristic of the membrane helps the plasma membrane remain fluid. The integral proteins and lipids exist as separate but loosely-attached molecules in the membrane. The membrane is a relatively...