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Flashcards in Enzymes 1 Deck (20):
1

What is an enzyme cofactor?

a nonprotein part required for activity

2

What is a coenzyme?

a complex organic molecule usually produced from a vitamin e.g NAD-

3

What is a prosthetic group?

cofactor covalently bound to the enzyme or very tightly associated with the enzyme

4

What is an apoenzyme?

protein component of an enzyme that contains a cofactor

5

What is a holoenzyme?

the whole enzyme - the apoenzyme AND the cofactor(s)

6

What do enzymes do? (3 things)

-increase RATES of spontaneous reactions
-lower the activation energy of biochemical reactions
-accelerate movement towards reaction equilibrium

7

What do enzymes NOT do? (2 things)

-move reaction equilibria
-make a non-spontaneous reaction spontaneous

8

What is Gibb's Free Energy?

'useful' energy - the energy that is available

9

What delta G value must a spontaneous reaction have?

negative

10

What is the calculation of of Gibb's Free Energy?

delta G= deltaH-TdeltaS

11

What happens to a reaction if there is no enzyme?

there is a high activation energy

12

What is the optimum shape of the active site in relation to the substrate?

active site complimentary to transition state

13

How do enzymes reduce activation energy? (3 ways)

-entropy reduction
-desolvation
-induced fit

14

What is meant by desolvation?

weak bonds between substrate and enzyme essentially replace most or all of H bonds between substrate and aqueous solution

15

What is meant by induced fit?

conformational change occurs in protein structure when substrate binds

16

Why does Vmax occur?

because all the enzyme active sites are saturated with substrate

17

What does V0 usually equate to?

the steady state of a reaction

18

What is the Km equivalent to?

the substrate concentration at which the initial reaction rate is half of the maximum reaction rate

19

What does Km tell you?

the affinity of an enzyme with its substrate

20

What does the Vmax tell you?

how fast a reaction is proceeding when the enzyme is saturated with substrate