Enzymes Flashcards
0
Q
Active site
A
Binding site of an enzyme
1
Q
Vmax
A
The point at which the enzymes are completely saturated
2
Q
How do enzymes differ
A
By enantiomers
- if its substrate is chiral
- specicifity is huge
3
Q
High Km
A
Lower affinity for substrate
4
Q
Low Km
A
Higher sffinity for substrate
5
Q
Half way to Vmax
A
Km
6
Q
Competitive inhibition
A
- when an inhibitor competes with the active site of a protein
- does not change Vmax
- imcreases the Km value (less affinity for substrate)
7
Q
Noncompetitive inhibition
A
- does not bind to the active site
- catalytic reaction doesnt take place
- Vmax goes down but Km remains unchanged
8
Q
Hemoglobin
A
- has four subunits that can bind oxygen
- has *cooperativity
- when the first subunit binds o2 is makes it easier for the second, then third and fourth
- myoglobin only has a single subunit
- in the tissues theres more co2 and acid which releases the o2 (bohr effect)
9
Q
Bohr effect
A
- at the tissues were more likely to let the oxygen go
- curve shifts
10
Q
Enzyme regulation
A
- need a way to turn them on and off
1. Allosteric regulation
2. Phosphorylation
3. Zymogens
4. Cofactors
5. Association with other peptides
11
Q
Allosteric regulation
A
- you will have other molecules besides the substrate that will bind to the enzyme in some site other than the active site
- sometimes they activate and sometimes they inhibit
- when they binds the protein changes its shape
- -if you change its shape you change itd ability to catslyze a rxn
12
Q
A - b - c - enzyme - d - e
Positive and negative feedback
A
If there is alot of a b or c, you need to activate the enzyme(positive feedback)
-if theres alot of d or e you need to inactivate the enzyme(negative feedback)
13
Q
Phosphorylation
A
- Also know as covalent modification because youre adding a covalent bond
- adding a phosphate group to an alcohol
- promotes a conformation change in the protein because phosphates have alot of negative charges
- sometimes it activates an enzyme and sometimes it deactivates an enzyme
14
Q
Enzymes that phosphorylate a protein
A
- kinases(use atp to provide the phosphate)
- phosphorylases (dont use atp)
- phosphatases dephosphorylate a protein
15
Q
Zymogens
A
-Inactive precursers that become active upon proteolytic cleavage
16
Q
Cofactors
A
Metal ions or organic molecules
