Enzymes Flashcards
Angiotensin I-Converting Enzyme
Angiotensin I-Converting Enzyme converts
angiotensin I (inactive) to angiotensin II (active) Inhibitors of Angiotensin I-Converting Enzyme are
used to treat hypertension e.g., captopril, lisinopri
Phosphofructokinase
Phosphofructokinase specifically adds a phosphate
group to fructose-6-phosphate Phosphofructokinase is an enzyme of the metabolic
cycle called “Glycolysis
feedback inhibition
Each step is determined by an enzyme so when one enzyme is inhibited then the reaction won’t be complete and the final product won’t be made
Feedback = product inhibits one of the enzymes to stop continues reaction
Regulatory proteins
They can inhibit or promote enzymatic activity
E.g blood coagulation cascade
Covalent modification
Can be reversible
E.g phosphorylation can switch an enzyme from being inactive to active
De phosphorylation can return it to its inactive state
Covalent modification can be irreversible
E.g proteolytic activation
Many peptidase are regulated this was
E.g in digestion trypsinogen in its inactive form reaches enter peptidase and becomes active
How do enzymes actually work ?
They stabilise transition states intermediaries between substrate and product
Key features of enzyme active sites
Active sites are 3 dimensional
Particular amino acids in the pocket drive the creation of micro environments for catalysis
water usually excluded unless necessary for
catalysis
Lock and key model compared to induced fit
Substrate is an exact fit either the enzymes active site
In induced fit the substrate and active site are different but the structure of the active site changes to accommodate the substrate
Rate of reaction
Referred to as velocity expressed as mol orc products per min
The Michaelis menton equation
For a fixed conc of an enzyme
At low substrate conc v linearly proportional to s
At high substrate conc v independent of s
Assumptions of Michaelis menton equation
Assumptions: products does not revert to substrate
The reaction is in a steady state condition e,g concentration of starting and end materials change
