RHSA SBI4U Name: ______
FACTORS INFLUENCING ENZYME ACTION – V3
An enzyme’s rate of reaction is measured by the amount of substrate converted to a product per minute. An enzyme’s activity can be affected by:
1. General environmental factors, such as temperature and pH.
2. Cofactors and coenzymes.
3. Enzyme and substrate concentration which affects the saturation of the active site.
4. Inhibitors.
1. Environmental Factors
Each enzyme has an optimal temperature in which it can function.
Each enzyme has an optimal pH in which it can function.
The wrong temperature of pH can denature an enzyme, which means the enzyme proteins shape is destroyed.
2. Cofactors and Coenzymes
Cofactors are nonprotein inorganic enzyme helpers.
For example, metal ions like iron in hemoglobin.
Coenzymes are organic cofactors.
For example, vitamins like niacin which serves as an electron acceptor.
3. Enzyme and Substrate Concentration
a) Increasing the [enzyme] means the rate of reaction keeps increasing.
b) Increasing [substrate] concentration only increases the reaction rate until all the enzyme active sites are in use.
4. Enzyme Inhibitors
Competitive inhibitors bind to the active site of an enzyme, competing with the substrate.
Noncompetitive inhibitors bind to another part of an enzyme, causing the enzyme to change shape and making the active site less effective.
Noncompetitive inhibition is also called allosteric inhibition.
Allosteric Regulation
Allosteric regulation is the term used to describe cases where an enzyme’s function is affected by the binding of a regulatory molecule at a different site than the active site.
Allosteric regulation may either inhibit or stimulate an enzyme’s activity.
Usually the end product of a long series of reactions that make a metabolic pathway inhibits an enzyme near the beginning of the pathway.
This way when the [product] is high the chemical reactions leading to the product are slowed down.
Homework.
2.a) Read MHR (2011) p 39-40, Do p 42 #3,7,9,12
b) Adapt and redraw the diagram on p 37 to illustrate an anabolic reaction instead of a catabolic reaction.
Note: anabolic = dehydration synthesis
catabolic = hydrolysis or breakdown
FACTORS INFLUENCING ENZYME ACTION – V3
An enzyme’s rate of reaction is measured by the ______. An enzyme’s activity can be affected by:
1. General environmental factors
2. Cofactors and coenzymes.
3. Enzyme and substrate concentration
4. Inhibitors
1. Environmental Factors
Each enzyme has an ______in which it can function.
Each enzyme has an ______in which it can function.
The wrong temperature or pH can ______an enzyme, which means the ______.
2. Cofactors and Coenzymes
Cofactors are ______.
For example, metal ions like iron in hemoglobin hold oxygen.
Coenzymes are ______.
For example, vitamins like niacin which ______.
3. Enzyme and Substrate Concentration
a) Increasing the ______.
b) Increasing ______only ______until all the enzyme ______.
4. Enzyme Inhibitors
Competitive inhibitors bind to the ______site of an enzyme, ______with the substrate.
Noncompetitive inhibitors bind to another part of an enzyme, causing the enzyme to ______and making the active site less effective.
Noncompetitive inhibition is also called ______regulation. Label the diagram to the right.
Allosteric Regulation
Allosteric regulation is the term used to describe cases where an enzyme’s function is affected by the binding of a regulatory molecule at a ______than the active site. Allosteric regulation may either ______or ______an enzyme’s activity.
Usually the end product of a long series of reactions that make a ______an enzyme near the ______of the pathway. This way when the ______is high the chemical reactions leading to the product are ______.
ALLOSTERIC REGULATION
Homework
1. Describe the effect of molecule G on the biochemical pathway shown in the diagram above. Be sure to use the terms [product], allosteric regulation(aka negative feedback), inhibition, metabolic pathway, active site, allosteric site and [substrate].
2.a) Read MHR (2011) p 39-40, Do p 42 #3,7,9,12 AND WATCH ENZYME VIDEOS
b) Adapt and redraw the diagram on p 37 to illustrate an anabolic reaction instead of a catabolic reaction.
Note: anabolic = dehydration synthesis
catabolic = hydrolysis or breakdown