1.6-Enzyme Regulation Flashcards
What is the main reason for loss of enzyme activity?
Denaturation
What is the term for and enzyme AND its cofactor?
A HoloEnzyme
What is the term for just the protein portion of a holoenzyme?
An ApoEnzyme
What is a tightly bound coenzyme that does not dissociate?
A Prosthetic Group
What is the difference between a coenzyme and a cofactor?
Cofactor is more general and can include metals, molecules, etc. Coenzyme is generally organic in nature
What are the three types of reactions involving enzymes?
- Random 2.Sequential 3. Double Displacement (PingPong)
What is Km for starch when introduced to the mouth?
Km is the concentration of starch when 1/2 of salivary amylase enzymes are taken up
What is the name of the kinetic relationship between constant [enzyme] and varying [substrate]?
Michaelis-Menten Kinetics
What are the three conditions for Michaelis-Menten Kinetics?
- LOTS more fries then Pacmen 2. Once a pac man clamps down he won’t let go. 3. Only the INITIAL velocity is used
If I have a substrate with a LARGE Km do I have a high or low affinity for that enzyme?
I have a LOW affinity.. Lots of fries to FINALLY reach the 1/2Vmax..
What does a SMALL Km tell me about the affinity of a substrate to an enzyme?
Small Km = HIGH affinity of the substrate for the enzyme
What is the double reciprocal plot that helps us determine Vmax?
A LineWeaver-Burke Plot
What is Kcat?
TURNOVER NUMER. The number of Substrate converted to Product PER Enzyme. (SO, how efficient is my pac man at eating stuff)
How do I find efficiency of my enzyme by relating Kcat to Km? What is the PERFECT enzyme?
Kcat/Km. The perfect enzyme will have a HIGH Kcat/LOW Km (so high turnover AND high affinity)
What were our two examples for very SPECIFIC enzymes? What are they specific to?
Urease: Urea & Catalase: H2O2
What was our example for a non specific enzyme?
CHYMO-trypsin
What does an inhibitor do?
Diminishes the VELOCITY of an enzyme catalyzed reaction
What kind of inhibition occurs when an enzyme does not regain activity upon dilution of the enzyme?
Irreversible Inhibition
What are the two MAIN types of reversible inhibition? I’m ignoring uncompetitve :)
- Competitive (@ active site) 2. Noncompetitive (Allosteric Site)
What effect does a COMPETITIVE inhibitor have on Vmax? Km?
No change in Vmax with an inhibitor. Inhibitors INCREASE Km. (Need to have more S to get the same 1/2Vmax)
What effect does a NONcompetitive inhibitor have on Vmax? Km?
DECREASES Vmax (Adding more S doesn’t do anything!). Km stays the same (S still binds to E).
What must the body do to compensate for an enzyme being irreversibly blocked? Think aspirin…
The body must produce more enzyme (which will take a while :)
What are the three CK (creatine kinase) Iso(en)zymes we discussed? Where can I find them?
BB in Brain, MB in Heart, MM in skeletal and heart muscle
What is another word for proenzymes/prohormones?
Zy-Mo-Gens
