Enzymes And Biochemical Pathways Flashcards
Define enzymes
Protein molecules that catalyse (speed up) chemical reactions.
What is the structure of an enzyme
Globular soluble tertiary protien.
Structure of enzymes are specific
What is the active site
Active site has a specific shape that will “fit” a specific substrate. It’s a pocket at the surface of the enzyme.
High specificity
The enzymes will only bind with a single type of substrate
Low specificy
The enzyme will bind a range of related substrates
What’s an anabolic reaction and steps for enzymes
Requires an input of energy Enzyme + substrate Enzyme substrate complex Enzyme product complex Enzyme + product
What’s a catabolic reaction and steps
Releases energy Enzyme + product Enzyme product complex Enzyme substrate complex Enzyme + substrate
What’s the lock and key model
Early theory proposed that the substrate was simply drawn into a closely matching cleft on the enzyme. Key is the substrate and lock is the active site
What’s the induced fit model
The enzyme or substrate change in shape
The substrate become bond to enzymes by weak chemical bonds
This binding can weaken bonds within reactants themselves allowing the reaction to proceed more readily
How do enzymes work
Enzymes are able to speed up reactions by changing the activation energy. The activation energy required with enzymes is lower therefore the reaction can occur quicker. Without enzymes the activation energy is higher therefore the process would take longer.
What factors affect rate of reaction involving enzymes
Temperature, pH, Substrate and enzyme concentration
What is irreversible inhibition
Occurs when a compound binds covalently to one or more amino acids and alters the structure of the enzyme affecting its active site.
These are termed poisons
What is reversible inhibition
The enzyme is not permenatly inhibited or damaged,
Noncovalent interactions that can be reversible and can dissociate from the enzyme
Removal of the inhibit actor reverses the inhibition
What are the two types of reversible inhibition
Competitive- occupy the active site and prevent the substrate molecule from binding to the enzyme
- they “compete” with the substrate for the active site.
Noncompetitive- inhibitors that attach to other parts of the enzyme molecule perhaps distorting its shape
