Section 5 Flashcards
What are the two models for binding interactions between enzymes and substrates?
- Lock-and-key
2. Induced-fit
How does the lock-and-key model bind to its substrates?
- Hydrophobic interactions
- Electrostatic interactions
- Hydrogen bonds
How does the induced-fit model bind to its substates?
Enzyme undergoes a conformational change that increases number of binding interactions.
Which AA participate in catalysis?
Polar AA
In activation-transfer coenzyme reactions, how do they connect w/ its substrate?
Covalent bonds
How do oxidation-reduction coenzyme reactions differ from activation-transfer reactions?
No covalent bonds
What role do metal ions serve in catalysis?
Acts as an electrophile; stabilizes anions and accept/donate e- in oxidation-reduction rxns.
Why does pH increase as rate of peptide bond cleavage increases?
Ionization of specific functional groups in the active site
Why is there a loss of activity on the basic side in terms of peptide bond cleavage?
Inappropriate ionization of AA residues
How does allopurinol work?
Inhibits xanthine oxidase; xanthine oxidase oxidizes allopurinol to oxypurinol which binds to Mo-S. which is unable to generate uric acid
What is Km?
Km is the concentration of S at which Vi=half Vm
In competitive inhibition, what does not change?
Vmax; increases Km
In noncompetitive inhibition, what does not change?
Km; decreases Vmax
How do you distinguish between competitive and noncompetitive inhibition?
Lineweaver-Burke plots
Where is hexokinase found?
RBC
