Enzyme Rate of Reaction: Factors & Catalysts

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Pyruvate Oxidation: Products & Overview

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 0:04 Why We Need Enzymes
  • 0:47 How Enzymes Work
  • 1:28 Impacting Reaction Rate
  • 5:00 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Speed Speed

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Dominic Corsini
What is an enzyme? Why are they important? How can they change? This lesson answers those questions. It teaches us how enzymes work and how they can be changed. It also includes illustrations, examples, and a brief quiz.

Why We Need Enzymes

When people complete seemingly routine life functions, such as eating, their bodies undergo chemical changes that are driven by enzymes. Enzymes are specialized proteins that act as catalysts for chemical reactions, getting the reactions going, in other words. Catalysts speed up chemical reactions without themselves being changed.

There are numerous enzymes within living organisms. Some of the more common ones found inside our bodies include amylase, protease, and lipase (to name a few). Each of these performs a specific function. For example, amylase helps break down the carbohydrates in the food we eat, protease breaks down proteins, and lipase breaks down fats. All enzymes are important and all work in similar ways.

How Enzymes Work

Enzymes help to speed chemical reactions by lowering activation energy, which is the energy required for a chemical reaction to occur. When enzymes are present, this energy requirement is lowered, allowing the reaction to occur more quickly. We can see an example of this:

Enzyme Function
Enzyme Function

This graphic has two lines showing the reaction rates with enzymes (in blue) and without enzymes (in red). The dotted line represents the activation energy needed for this reaction to occur. Notice how there's less required energy in the enzyme driven reaction. The enzyme allows the reaction to occur more quickly than the reaction without an enzyme. Enzymes are highly useful; however, their reaction rates can be altered by their surroundings.

Impacting Reaction Rate

There are several factors that can influence the rate of enzyme reactions. The most common include changes to pH, temperature, or substrate concentration. The substrate is the compound an enzyme bonds with. More on this later.

All enzymes have an optimal pH they work best in. The pH scale runs from 1 to 14 and is a measure of how acidic or basic a substance is. For example, something with a pH value of 2 represents a strong acid, such as lemon juice. Conversely, a pH value of 13 represents a strong base, such as bleach. Outside their optimal ranges, enzymes work less effectively. This is easily illustrated with the help of graphics. Have a look at this diagram:

Optimal Enzyme pH
Optimal Enzyme pH

This image demonstrates how pH influences enzyme activity. Here we have three different enzymes (pepsin, salivary amylase, and arginase). See how pepsin works very well at a pH of 2, yet both salivary amylase and arginase fail to function? This is because pepsin's optimal pH is around 2, while salivary amylase has an optimum of around 7, and arginase at roughly 9.5. Placing an enzyme in an environment with its optimal pH will increase the rate of reaction. If the environment is outside its optimal range, the enzyme rate of reaction will decrease.

Changing the temperature can also cause fluctuations in rates of reaction. Again, as with pH, all enzymes have an optimum temperature. However, when explaining how temperature influences rate of reaction we can use general trends. This is because increasing temperatures will increase the rate of reaction for nearly all enzymes while decreasing temperature will have an inverse effect. Take a look at the following example:

Influence of Temperature on Enzyme Function
Influence of Temperature on Enzyme Function

In this graphic, we can see how the rate of reaction is increasing as the temperature increases. However, once a certain temperature is reached (approximately 40 degrees Celsius for most enzymes) the rate of reaction decreases rapidly. This is because the enzyme is being denatured or essentially destroyed. A denatured enzyme either fails to function or functions very poorly. So, to recap, rate of reaction increases with increasing temperatures until the temperature gets too warm, then the enzyme denatures.

To unlock this lesson you must be a Study.com Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use Study.com

Become a Study.com member and start learning now.
Become a Member  Back
What teachers are saying about Study.com
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? Study.com has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create an account