Enzymes

Question 1

what is an enzyme co-factor?

Answer 1

non - protein component needed for enzymatic activity

Question 2

what is a co-enzyme?

Answer 2

a complex organic molecule, usually formed from vitamins - required for an enzyme to work. (e.g NAD FAD)

Question 3

what is a prosthetic group?

Answer 3

cofactor covalently bonded to an enzyme or very tightly associated with the enzyme.

Question 4

what us apo- enzyme?

Answer 4

The enzyme ( a protein) which is with the co-factor

Question 5

What is holoenzyme?

Answer 5

The enzyme plus the co-factor.

Question 6

How do enzymes catalyse reactions?

Answer 6

They increase the rate of spontaneous reactions.
Lowers the activation energy
Accelerates movement towards equilibrium.

Question 7

How does the rate of an enzyme catalysed reaction change with the conc of substrate

Answer 7

as the substrate conc increases - the velocity of the reaction will increase. rapidly at first and then level out at Vmax. Vmax is when the ENZYME is fully saturated

Question 8

What is the michaelis constant?

Answer 8

Km = K.1 + K2/K1

Question 9

What does the michaelis constant do?

Answer 9

it tells us about affinity of the enzyme for the substrate.
Large Km - less stable ES complex
Low Km - more stable ES complex.

Question 10

How do competitive inhibitors work?

Answer 10

Bind non- covalently to enzyme at active sight.
Increases Km - as affinity for proper substrate decreases.
Increase conc - Vmax can still be achieved as substrate can displace competitor

Question 11

How does non - competitive inhibitors work?

Answer 11

Inhibitors bind not covantlently to a secondary site. Km unchanged (as enzyme does not bind to active sight). Vmax will decrease - can increasing the conc of substrate won’t help - as the inhibitor cannot be displaced

Question 12

how does non -competitive inhibition affect Vmax and Km?

Answer 12

Vmax - decreases

Km - stays the same

Question 13

How does competitive inhibition affect Vmax and Km?

Answer 13

Vmax - stays the same

Km - increases

Question 14

Metabolites binding to allosteric site can do what? (non - competitive inhibition)

Answer 14

Enzyme inhibitor or enzyme activator

Question 15

what are allosteric enzymes?

Answer 15

Multisubunit proteins affected by binding of other molecules (effector).
Binding of an effecter at one subunit, has structural and functional effects on other subunits

Question 16

Explain a concerted model allosteric enzyme

Answer 16

each subunit can exist in 2 different conformations - low Km and high Km.

When theres no substrate, the enzyme flips between the conformations.
Units are in the same confirmation (concert)

1 substrate binds - holds enzyme open - increases affinity

Question 17

Explain a sequential model allosteric enzyme

Answer 17

No flipping between different conformational states

Binding causing change in one subunit - then change in enough making binding easier.

Question 18

what do oxidorededucatases do?

Answer 18

tranfers electrons

Question 19

what do transferases do?

Answer 19

transfers groups

Question 20

what do hydrolases do?

Answer 20

hydrolysis - breakdown due to reaction with water

Question 21

what do lysases do?

Answer 21

add double bond

Question 22

what do isomerases do?

Answer 22

form isomers

Question 23

what do ligases do?

Answer 23

Form C-C, C-S, C-O, C-N bonds

Question 24

do enzymes make non - spontaneous reactions spontaneous?

Answer 24

NO

Question 25

What is the transition state and what could happen from here??

Answer 25

it is the top part of the curve - the moment that chemical bonds are formed and broken. from here it could go back to S or to P

Question 26

Is the active site complementary to the substrate?

Answer 26

Nope. The active sight is complimentary to the transition state.

Question 27

How do enzymes reduce activation energy?

Answer 27

Entropy - more order so they are correctly orientated
Desolvation - weak bonds between substrate and enzyme replace H- bonds between substrate and aqueous solution
Induced fit - conformational change

Question 28

What are isoenzymes?

Answer 28

Different enzymes that catalyse the same reaction - e.g hexokinase and glucokinase

Question 29

How can u study isoenzymes?

Answer 29

electrophoresis

Question 30

do allosteric enzymes follow the M-M equation?

Answer 30

Nope.

Question 31

give the product to substrate equation

Answer 31

E+S <> ES <>EP<> E + P