ENZYME ACTIONS Flashcards
What are the reactant conditions for enzymes in biological systems?
37 degrees celcius (low temps), Low reactant concentrations, neutral pH (except for stomach and lysosomes)
Which enzyme is very general and can break any peptide bond?
chymotripsin
What do isomerases do?
Change arangement of functional groups
What do lysases do?
Cleavage of C-C,C-O, C-N or other bonds by elimination, leaving doulbe bonds or rings, or addition of groups to double bonds.
What do oxidoreductases do?
Transfer electrons (hydride ions or H atoms)
What do ligases do?
The opposite of lysases. So they form the C-X bonds by condensation reactions.
Is the transition state stable or unstable?
UNSTABLE!! It is the state where neither original or final molecules are present.
Which type of binding occurs between substrate and active site?
NON covalent interactions; ionic bonds, H bonding, hydrophobic interactions
What does NOT CHANGE due to presence of enzymes?
Gibbs free energy or equilibrium
What are enzymes most adapted to binding?
The transition state between substrate and product, which facillitates the formation of transition state (decreasing the activation energy of the reaction)
What are prosthetic groups also known as?
Vitamins
What is an apo enzyme?
An inactive enzyme
What are the three types of reversible inhibition?
Competitive, uncompetitive, noncompetitive (mixed)
What is competitive inhibition?
Inhibitor binds to active site but is not processed
What is uncompetitive inhibition?
Inhibitor binds to separate site, inhibitor only binds to ES complex not just the enzyme.
What is mixed, non competitive inhibition?
- inhibitor binds to a site other than the active site, may bind to E or ES complex, may not affect the binding of the substrate.
How is the rate of enzyme catalysis measured?
Through:
- substrate dissappearance
- Product formation
What is Vmax?
Maximal velocity that enzyme can go to at particular temp and concentration (enzyme)
Is the michaelis mentum plot linear or curved?
Curved - Michaelis constant is Km.
What is a lineweaver burke plot and what is it used for?
Linear plot that is the inverse of Km and Vmax and substrate concentration. (1/[s]) (1/vmax) 1/km) slope= km/vmax
- Can see what happens to enzymes activity in the presence of an INHIBITOR.
What are the features of the lineweaver burke plot in competitive inhibition?
No change in vmax, because at high sub conc. vmax will be reached. Will have AN INCREASE IN APPARENT KM. –> because efficiency of enztme interaction with substrate decreased .
What are the features of the linweaver burke plot for uncompetitive inhibition?
Vmax decreases with INCREASED inhibitor (catalysis is being prevented)
- Km decreases (because locking the ES complex together)
What are the features of the lineweaver burke plot in noncopetitive (MIXED) inhibition?
Vmax also dereases with INCREASED inhibitor(catalysis being prevented)
Effects on Km are combinationof INTERFERENCE BY INHIBITOR AND LOCKING OF e-S COMPLEX
mixed effect
(inhibitor can bind just with the enzme (not substrate aswell)) and ALSO bind with substrate.
What are allosteric enzymes?
Have quaternweery structure. Kinetics different from Michaelis mentum.
- BAsed on sigmoidal kinetics
- substrate or molecular bonding induces conformational change to facilitate binding - enzyme is flexible.
