First Five

First FiveExplain the meaning of the following terms:

enzymesubstrateproductactive sitedenatured

What are Enzymes? Globular proteins that act as biological catalysts

to increase reactions rates

Catalysts: substances that speed up reactions w/o being consumed

Biological? Because they are proteins; NOT because they are alive (they aren’t!)

Enzymes: How they workspeed up biochemical reactions by lowering the activation energy of reactions that would normally happen anyway.

Mode of Action Enzymes bind substrates (enzyme reactant) into active sites (pocket or groove on enzyme).

While the enzyme and the substrate are joined, the enzyme catalyzes the reaction and converts the substrate to the product(s).

Enzymes A classic example of an enzymatic reaction is

the hydrolysis of sucrose into glucose and fructose.

Enzymes Another look…

PracticeFind the enzyme, substrate(s), and product(s) in the sentences.

I) Acetylcholinesterase breaks down acetylcholine into acetyl and choline. Enzyme: ________________________ Substrates: ______________________ Products: _______________________

II) A disaccharide can be broken down into glucose and fructose by lysozyme

Enzyme: ________________________ Substrates: ______________________ Products: _______________________

PracticeFind the enzyme, substrate(s), and product(s) in the sentences.

I) Acetylcholinesterase breaks down acetylcholine into acetyl and choline. Enzyme: Acetylcholinesterase Substrates: acetylcholine Products: acetyl & choline

II) A disaccharide can be broken down into glucose and fructose by lysozyme

Enzyme: lysozyme Substrates: sucrose Products: glucose & fructose

Factors Affecting Enzyme Activity

Factors Affecting Enzyme Activity: Rate of Reaction vs Enzyme Concentration

Describe the activity of the enzyme as concentration of the enzyme increases.

Enzyme activity increases as enzyme concentration increases. Eventually enzyme activity plateaus even though enzyme concentration continues to increase.

Factors Affecting Enzyme Activity: Rate of Reaction vs. Temperature

Increasing heat energy causes more collisions between enzyme and substrate, until an optimal temperature is reached.Above the optimal temperature, the enzyme denatures so the rate falls rapidly.

Describe the activity of the enzyme as temperature increases.

Factors Affecting Enzyme Activity: Rate of Reaction vs. pH

Describe the activity of the enzyme as pH increases.

Activity gradually increases up to the optimal pH and gradually decreases after the optimal pH.

Rate of Enzyme Activity is influenced by:◦ Substrate concentration

◦ more substrate = more activity until saturation◦ Amount of enzyme

◦ more enzyme = more activity until saturation◦ Temperature

◦ higher temperature = more activity until the enzyme’s protein denatures◦ pH

◦ usually in range of 6-8 for enzymes in humans◦ Inhibitors

◦ reduce activity by binding or changing shape of active sites

Effects on Enzyme Activity

Two types of inhibitorsCompetitive Inhibitor

When something besides the substrate blocks the active site

Noncompetitive InhibitorWhen a molecule binds to

another spot on the enzyme causing it to change shape and become inactive

Enzyme SimulationRules:Only do your action upon your substrate.

The starting substrate and ending product must match the picture on your enzyme’s instructions.

If you can’t operate upon a particular substrate, move it on to another person or another table. 

Enzyme E is the last step in the process.  Although the description only shows two of the monomers stuck on the pencil, it will continue adding more and more until it is full.