FINAL EXAM CHAPTER 8 Mechanisms and inhibitors Flashcards
What is covalent catalysis?
The active site contains a nucleophile that is briefly covalently modified
What is General acid-base catalysis?
A molecular other than water donates or accepts a proton.
What is Metal ion catalysis?
Metal ions function in a number of ways, including serving as an electrophilic catalyst
What is Catalysis by approximation and orientation?
The enzyme brings two substrates together in an orientation that facilitates catalysis
THERE WILL BE A QUESTION ON THIS
What impact does temperature and pH have on enzyme function?
-Temperatures enhances the rate of enzyme catalyzed reactions. but if too high it breaks the structure and with low temp its harder for them to interact.
-Most enzymes have an Optimal pH
What does optimal pH in enzymes mean?
At a certain pH the maximum amount of activity by the enzyme is shown but with increasing pH it depronates but its gradual
What is competitive inhibiton? and what effect does it have on the Vmax and Km? and what does it look like on the lineweaver burke plot?
-The inhibitor is structurally similar to the substrate and can bind to the active preventing the actual substrate from binding
- Vmax of the enzyme is unchanged because it can be overcome by sufficiently high concentration of substrate
- Km is increased in the presence of an inhibitor
- -1/Km will move closer to 0 and more steep if the inhibitor is present
What is uncompetitive inhibiton? and what effect does it have on the Vmax and Km? and what does it look like on the lineweaver burke plot?
-The inhibitor binds only to the enzyme substrate complex, and it can only bind when enzyme is binded to the substrate
-Vmax is lower in the presence of inhibitor
-Km is also lower
-The -1/Km moves closer to the negative side and the lines are parallel
What is non competitive inhibition? and what effect does it have on the Vmax and Km? and what does it look like on the lineweaver burke plot?
-The inhibitor binds either the enzyme or enzyme substrate complex, this binds regardless if the enzyme is binded or not
- Vmax is lower in the presence of inhibitor
-Km is not changed
- 1/V max increases but 1/Km doesn’t move
What are irreversible inhibitors?
-Bind very tightly to enzymes
What is the use of Irreversible inhibitors in determining the enzyme mechanisms?
-You can use things like DIPF to check is Ser AA is needed for some enzymes to function
-You can also use affinity labelling of Chymotrypsin to check if in the active site if HIs is needed
- there are also suicide inhibitors that basically bind to the enzyme as substrate and then kill itself making it irreversible
What is a Chymotripsin and what does it get secreted by and what does it hydrolyze?
-a Proteolytic enzyme
- Secreted by pancreas
-hydrolyzes peptide bonds selectively on the carboxyl side or large hydrophobic amino acids
What is the oxyanion hole?
-A region of the active site , stabilizes the tetrahedral reaction intermediate
What is the Catalytic Triad
a group of three amino acids that are found in the active sites of some proteases involved in catalysis.
What is the S1 pocket?
-It is a hydrophobic pocket that binds a hydrophobic residue on the substrate and positions the adjacent peptide bond for cleavage
-This basically puts the Serine that needs to be cut in the right spot to be cut
