Biochemistry: Why does a high pH kill/inhibit yeast function?

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Discussion Overview

The discussion revolves around the influence of pH on yeast function, specifically in the context of a wine analysis experiment. Participants explore how high concentrations of hydrogen ions (H+) may affect yeast growth and metabolism, particularly in relation to enzyme activity during fermentation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant inquires about the mechanism by which high H(+) concentrations inhibit yeast function, suggesting that hydrogen ions may break down enzymes involved in fermentation.
  • Another participant explains the role of pH in protein structure, noting that pH affects the charge of amino acids, which in turn influences enzyme folding and function.
  • A clarification is provided that a high concentration of H(+) corresponds to a low pH, which may impact the discussion on yeast function.

Areas of Agreement / Disagreement

Participants present multiple viewpoints regarding the effects of pH on yeast function, with no consensus reached on the specific mechanisms involved. The discussion remains exploratory with differing interpretations of the relationship between pH and enzyme activity.

Contextual Notes

Limitations include the need for further clarification on the specific pH levels that affect yeast function and the potential variability in enzyme responses to pH changes.

Orlando
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I am conducting a wine analysis experiment for my undergraduate biochemistry course and am a bit stuck on the influence of pH on yeast function. Why does a high H(+) concentration kill the yeast or inhibit its growth/metabolisation of the glucose? I am guessing that the hydrogen ions somehow break down the enzymes within the cell that catalyse the fermentation process? If anyone knows what's going on I would greatly appreciate the help.
 
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subbed for interest. Doing wine chemistry this term
 
Enzymes are proteins, which means that they are composed of a long chain of amino acids that folds into a specific shape. This overall folding of the protein precisely positions the side chains of a few amino acids to form a so-called active site that can catalyze chemical reactions. A variety of intermolecular forces hold the protein in this shape. One important force is electrostatic interactions between positively and negatively charged amino acid residues.

pH becomes important in determining the shape that proteins adopt because at different pH values, certain amino acid side chains can become charged or uncharged. For example, the amino acid histidine has a positive charge at pH values below ~6 and a neutral charge at pH values above ~6. Since pH affects the charges of amino acids, it will affect the electrostatic forces that maintain an enzymes shape. At pH values far from the ideal pH of an enzyme, many important amino acid residues will have the wrong charge and therefore,the enzyme will not be able to fold into the right shape to function properly.

tl;dr: changing the pH of a solution can cause enzymes to misfold
 
Orlando said:
a high H(+) concentration

means LOW pH.
 
Thank you to all who answered, i appreciate it.
 

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