How is the LDH isoenzyme in the heart different from the LDH isoenzyme in the liver?
Ch.16 Amino Acids, Proteins, and Enzymes
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook
Chapter 16, Problem 43a
Trypsin, a peptidase that hydrolyzes polypeptides, functions in the small intestine at an optimum pH of 7.7 to 8.0. How is the rate of a trypsin-catalyzed reaction affected by each of the following conditions?
a. changing the pH to 3.0
Verified step by step guidance1
Understand the role of trypsin: Trypsin is an enzyme that catalyzes the hydrolysis of polypeptides in the small intestine. Enzymes have an optimum pH range where they function most effectively, and for trypsin, this range is 7.7 to 8.0.
Recall the effect of pH on enzyme activity: Enzymes are sensitive to pH changes because pH affects the ionization of amino acid side chains in the active site. Significant deviations from the optimum pH can lead to denaturation or reduced activity.
Analyze the given condition: The problem states that the pH is changed to 3.0, which is highly acidic compared to trypsin's optimum pH range. This drastic change in pH can disrupt the enzyme's structure and active site functionality.
Predict the impact on the reaction rate: At pH 3.0, trypsin is likely to lose its catalytic efficiency due to denaturation or altered active site geometry, leading to a significant decrease in the rate of the trypsin-catalyzed reaction.
Conclude the reasoning: The rate of the trypsin-catalyzed reaction will be negatively affected because the enzyme is no longer operating within its optimal pH range, and its ability to bind substrates and catalyze reactions is compromised.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Enzyme Activity and pH
Enzymes, including trypsin, have an optimal pH range in which they function most effectively. Deviations from this range can lead to denaturation or reduced activity, as the enzyme's structure and active site may be altered. For trypsin, which operates best at a pH of 7.7 to 8.0, a drop to pH 3.0 would significantly impair its catalytic ability.
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Factors Affecting Enzyme Activity Concept 2
Trypsin Function
Trypsin is a serine protease that specifically cleaves peptide bonds in proteins, facilitating digestion in the small intestine. It is secreted as an inactive precursor, trypsinogen, and activated by other enzymes. Understanding its role in protein digestion is crucial for analyzing how changes in conditions affect its activity.
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Logarithmic Functions
Reaction Rate and Environmental Conditions
The rate of enzyme-catalyzed reactions is influenced by various environmental factors, including pH, temperature, and substrate concentration. Changes in these conditions can either enhance or inhibit the reaction rate. In the case of trypsin, lowering the pH to 3.0 would likely decrease the reaction rate due to unfavorable conditions for enzyme activity.
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Rate of Reaction Concept 1
Related Practice
Textbook Question
Textbook Question
Pepsin, a peptidase that hydrolyzes proteins, functions in the stomach at an optimum pH of 1.5 to 2.0. How is the rate of a pepsin-catalyzed reaction affected by each of the following conditions?
a. changing the pH to 5.0
Textbook Question
What are isoenzymes?
Textbook Question
Trypsin, a peptidase that hydrolyzes polypeptides, functions in the small intestine at an optimum pH of 7.7 to 8.0. How is the rate of a trypsin-catalyzed reaction affected by each of the following conditions?
b. running the reaction at 75 °C
Textbook Question
A patient arrives in an emergency department complaining of chest pains. What enzymes would you test for in the blood serum?
Textbook Question
The following graph shows the activity versus pH curves for pepsin, sucrase, and trypsin. Estimate the optimum pH for each.
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