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Ch.16 Amino Acids, Proteins, and Enzymes
Timberlake - Chemistry: An Introduction to General, Organic, and Biological Chemistry 13th Edition
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook
Chapter 16, Problem 43b

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

Verified step by step guidance
1
Understand the role of trypsin: Trypsin is an enzyme that catalyzes the hydrolysis of polypeptides into smaller peptides or amino acids. Enzymes are highly sensitive to environmental conditions such as temperature and pH.
Recall the effect of temperature on enzyme activity: Enzymes typically have an optimal temperature range where their activity is maximized. For most human enzymes, this range is close to body temperature (around 37 °C). Temperatures significantly above this range can denature the enzyme, causing it to lose its functional shape.
Analyze the given condition: The reaction is being run at 75 °C, which is much higher than the typical optimal temperature for trypsin. At this elevated temperature, the enzyme's structure is likely to be disrupted (denatured), leading to a significant decrease in its catalytic activity.
Explain the impact on the reaction rate: When trypsin is denatured, it can no longer effectively bind to its substrate or catalyze the reaction. As a result, the rate of the trypsin-catalyzed reaction will decrease drastically or stop altogether.
Conclude the reasoning: Running the reaction at 75 °C negatively affects the rate of the trypsin-catalyzed reaction due to enzyme denaturation caused by excessive heat.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Enzyme Activity

Enzyme activity refers to the rate at which an enzyme catalyzes a reaction. Factors such as temperature, pH, and substrate concentration can significantly influence enzyme activity. For trypsin, an optimal pH of 7.7 to 8.0 is crucial for its function, as deviations can lead to decreased activity or denaturation.
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Temperature Effects on Enzymes

Temperature affects enzyme activity by influencing molecular motion and the kinetic energy of the substrate and enzyme. Generally, increasing temperature accelerates reaction rates up to a certain point, beyond which enzymes may denature, losing their functional shape. For trypsin, running the reaction at 75 °C could lead to reduced activity or complete inactivation.
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Denaturation

Denaturation is the process by which an enzyme loses its three-dimensional structure due to external stressors, such as extreme temperatures or pH levels. This structural change can render the enzyme inactive, as it can no longer bind to its substrate effectively. In the case of trypsin, exposure to high temperatures like 75 °C may cause denaturation, significantly impacting its catalytic function.
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