Chapter 3: Enzymes Flashcards
Enzymes
biological catalysts, protein molecules that speed up a chemical reaction but remain unchanged at the end of the reaction
Intracellular
Enzymes that function within the cell
Extracellular
Enzymes that function outside of the cell
Active Site
The region/cleft/depression where the substrate can bind to the enzyme
Substrate
The substance that binds to the enzyme
Substrate Complex
Where the substrate binds to an enzyme with a specific shape that can only fit that substrate. Temporary bonds are formed between the hydrophilic R groups of the enzyme and the substrate
Product Complex
The interaction between R groups of an enzyme and atoms of a substrate can break or encourage the formation of bonds in the substrate molecule, forming 1,2, or more products
Lock and Key Hypothesis
Each enzyme has a specific structure in which only a specific substrate can fit into.
Enzyme = lock
Substrate = Key
Induced Fit Hypothesis
Enzymes can change to fit the structure of a substrate. Can explain why one enzyme may have multiple substrates
Activation Energy
The extra energy needed to convert a substrate into its products
Initial Rate of Reaction
Where the rate of reaction is steepest towards the beginning of the reaction
The slope of the tangent to the curve at the first 30 seconds
Inhibitor
Molecules that reduce the rate of reaction of an enzyme
Usually specific and work in low concentrations
Block enzymes, do not destroy them
Competitive, Reversible Inhibition
When an inhibitor briefly binds to an enzyme’s active site, taking the place of a substrate and creating competition between the two
Non-Competitive, Reversible Inhibition
May bind somewhere else on the enzyme to change the shape/active site
While present, the substrate cannot bind to the enzyme
End Product/Feedback inhibition
When an end product of a reaction binds to the allosteric site of an enzyme, it changes the structure of the active site which shuts down the pathway of the reaction
Allosteric Site
Another site on an enzyme
Turnover Rate
The rate at which an enzyme can produce products
Typical enzyme turnover rate is 1000 substrates/second
V Max
The theoretical maximum rate at which an enzyme can work where it is completely saturated by substrates
Optimum
The condition at which the enzyme works at its best can be applied to pH and temperature
Denaturation
When an enzyme is changed to a point where it cannot continue to function
Immobilized Enzymes
Enzymes that have been put into a shape in which they can be recycled
pH
The concentration of hydrogen ions
