Things to know

Pepsin, a common enzyme found in the stomach, is most active at pH values between 0.5 and 2.5. It works slowly between pH values of 2.6 and 3.4. Beyond a pH of about 3.5, it becomes completely inactive. Why does this happen? Question 1

answer The protein chain in the enzyme is denatured, permanently inactivating it as the pH approaches 7.

Salivary amylase is an enzyme found in the mouth Salivary amylase is an enzyme found in the mouth. It breaks down starch into sugars. Why will it not break down Protein?

ACTIVE SITE

The human stomach secretes an enzyme known as pepsin The human stomach secretes an enzyme known as pepsin. This enzyme breaks down proteins into smaller chemical molecules called peptides. If pepsin was mixed in a laboratory with sugar molecules like glucose, what is the MOST LIKELY result?

Pepsin will probably NOT react with the sugar glucose since it is an enzyme that breaks down proteins.

Amylase becomes denatured at a temperature of 80°C Amylase becomes denatured at a temperature of 80°C. During an experiment to study the effect of varying temperature on enzyme activity, amylase's reactivity with starch was measured at body temperature (37°C), and then again at an increased temperature of 42°C. How would this increase in temperature affect the experiment?

The rate of reaction will increase.

A solution of an enzyme and a substrate was placed in a water bath and the temperature of the reaction was raised gradually. The graph shown was plotted at the end of the experiment. What can be concluded from the graph?

The enzyme shows increased activity up to a certain temperature.

Each enzyme has an optimum pH at which it attains is maximum activity Each enzyme has an optimum pH at which it attains is maximum activity.  That optimum pH varies for each enzyme. The optimum range for pepsin is 1.5 - 2; for stomach lipase it is 4.0-5.0. Any change below or above the optimum pH range for a specific enzyme results in a decrease in enzyme action. What would the graph for this look like? Sketch it quickly

In an experiment to study the effect of amylase on starch, samples of substrate and enzyme solutions are taken. The volumes of substrate and enzyme solutions in each sample are the same. The temperature at which the experiment is performed is also constant. The buffer solutions used for the experiment have pH 3, pH 5, pH 7, pH 9, and pH 11.  What can be BEST predicted about the result?

The results would vary because the active sites of amylase in each sample are different.

Josh finds that there definitely is a relationship between enzyme action and temperature and graphs his results. The enzyme functions as a biological catalyst and has its optimum effectiveness at_____________

39 degrees

The role of enzymes in biological systems is to catalyze chemical reactions. In 1894, chemist Emil Fischer proposed the lock and key analogy of enzyme action. This analogy explains the specific action of an enzyme with a single substrate. Compare the two models seen here. How do they BOTH represent the lock and key analogy?

Only a specific substrate fits into the active site of the enzyme.