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Flashcards in Enzyme Kinetics Deck (15)
1

2 Mechs of Enzymes Decreasing DeltaG (and kind of effect each is)

Ground state destabilization (DeltaH effect)
Transition state stabilization (DeltaS effect)

2

4 Mechs of Catalysis (and 1 major point)

General Acid/Base Catalysis
Electrostatic catalysis
Covalent catalysis
Entropy
- All chemical rxns entail charge redistribution

3

2 Properties of Enzyme Active Sites

Invaginated pocket to position things close, DeltaS effect
Microenvironment affects ionization status (pKa) of enzyme and substrate groups

4

2 Reasons Why Initial Velocity Must be Taken Immediately

1. [A] is well approximated by [A]i
2. Amount of [P] is negligible and won't interfere

5

Requirement for Continuous Assays (2)

Ability to measure either disappearance of substrate or appearance of product

6

"Coupled" Continuous Assays (2)

For when substrate-products have no spectroscopic properties - couple a given product to a rxn that does yield spectroscopic properties

7

Discontinuous Assay (reason & method)

When substrate-product exhibits similar/no spectroscopic properties
Radiolabel substrate, quench the rxn at different times, wash away radiolabeled substrate and measure product

8

kcat

Turnover number, maximum number of substrate molecules converted to product per unit time

9

Km

Michaelis constant, substrate concentration [A] that yields 1/2 Vmax

10

kcat/Km

Specificity constant

11

2 Conclusions of Competitive Inhibitors

kcat independent of [I[
Km increases linear w/ [I]

12

2 Conclusions of Uncompetitive Inhibition

kcat decreases hyperbolic w/ [I]
Km decreases hyperbolic w/ [I]

13

2 Conclusions of Noncompetitive Inhibition

kcat decreases hyperbolic w/ [I]
Km independent of [I]

14

Conclusion of Enzyme w/ Multiple Active Sites w/ No Cooperativity

Impossible to kinetically distinguish b/w 1 mole of enzyme w/ n identical sites and n moles of enzyme with a single site

15

Main Conclusion of Enzymes w/ Multiple Active Sites w/ Positive Cooperativity

Provides enhanced sensitivity to changes in [A] in narrow physiological range (S-shaped curve)