Question

Trypsin, a peptidase that hydrolyzes polypeptides, functions in the small intestine at an optimum pH of \(7.7-8.0 .\) How is the rate of a trypsin- catalyzed reaction affected by each of the following conditions? a. lowering the concentration of polypeptides b. changing the \(\mathrm{pH}\) to \(3.0\) c. running the reaction at \(75^{\circ} \mathrm{C}\) d. adding more trypsin

Short answer

a. Decreases rate. b. Decreases rate. c. Decreases rate. d. Increases rate.

Step-by-step solution

Identify Optimum Conditions

Trypsin works optimally at a pH of 7.7-8.0 and at a suitable body temperature of around 37°C. The concentration of polypeptides is also a factor that influences the reaction rate.

Evaluate Lowering Polypeptide Concentration

Lowering the concentration of polypeptides will reduce the substrate available for trypsin. This will decrease the rate of the trypsin-catalyzed reaction because there are fewer peptide bonds to hydrolyze.

Assess Changing the pH to 3.0

Changing the pH to 3.0 creates a highly acidic environment. This is far removed from the optimum pH of 7.7-8.0, likely leading to denaturation of trypsin. Consequently, the enzyme’s activity would significantly decrease or stop.

Consider Running the Reaction at 75°C

Running the reaction at 75°C is well above the normal body temperature of 37°C and exceeds the temperature range where trypsin is stable. The high temperature will likely denature the enzyme, drastically reducing or completely inhibiting its activity.

Analyze Adding More Trypsin

Adding more trypsin increases the concentration of the enzyme. If there is an excess of substrate (polypeptides), increasing enzyme concentration will increase the reaction rate until all substrate molecules are being processed as efficiently as possible.

Key concepts

enzyme kinetics

Enzyme kinetics is the study of how enzymes bind to substrates and convert them into products. The most important factors include:
* Enzyme concentration
* Substrate concentration
* Temperature
* pH

When studying enzyme kinetics, it is essential to understand the relationship between these factors and the reaction rate. Generally, as the concentration of substrate increases, the rate of reaction increases until the enzyme becomes saturated. This can be described using the Michaelis-Menten equation, which is expressed as:
\[ V = \frac{V_{max} [S]}{K_m + [S]} \]
where \[ V \] is the reaction rate, \[ V_{max} \] is the maximum rate, \[ [S] \] is the substrate concentration, and \[ K_m \] is the Michaelis constant.

enzyme denaturation

Enzyme denaturation refers to the structural alteration of an enzyme, causing it to lose its functionality. Factors like temperature and pH can cause denaturation:
* High temperatures, as seen in step 4, can lead to the unfolding of the enzyme's structure.
* Drastic pH changes, as mentioned in step 3, can interfere with the bonds holding the enzyme's structure together.

Denaturation is often irreversible, leading to a complete loss of enzymatic activity. For trypsin, extending beyond its stable temperature and pH range can severely affect its ability to catalyze reactions.

optimum pH

Every enzyme has an optimum pH at which it functions best. For trypsin, the optimum pH is between 7.7 and 8.0. This range optimizes the enzyme's active site configuration, allowing it to efficiently bind to substrates and catalyze reactions.

If the pH deviates significantly from this optimum range:
* The enzyme's structure might change.
* The substrate binding could be affected.
* The overall reaction rate may decrease due to reduced enzyme activity.

In step 3, changing the pH to 3.0 creates an environment too acidic for trypsin, leading to its denaturation and reducing its activity drastically.

reaction rate

The reaction rate determines how quickly an enzyme-catalyzed reaction occurs. Influencing factors include:
* Enzyme concentration
* Substrate concentration
* Temperature
* pH

In terms of trypsin, the reaction rate can be affected in various ways:
* Reducing substrate concentration (step 2) slows down the reaction.
* Altering the pH to extreme levels (step 3) decreases the activity rate.
* High temperatures (step 4) lead to denaturation and cessation of activity.
* Increasing enzyme concentration (step 5) can initially increase the rate until all substrates are saturated by enzymes.

substrate concentration

Substrate concentration is crucial for enzyme-mediated reactions. Enzymes act on substrates to convert them into products. Here are some key points:
* As substrate concentration increases, the reaction rate increases up to a certain point.
* Beyond this point, adding more substrate won't increase the rate because the enzyme becomes saturated.
* In step 2, lowering substrate concentration slows down the reaction rate.

The concentration of polypeptides in the trypsin-catalyzed reaction directly influences how many substrate molecules can bind to the enzyme at a given time. When substrate levels are low, fewer enzyme-substrate complexes form, leading to a slower reaction.