Enzymes

Question 1

What do proteases do

Answer 1

Hydrolyze peptide bonds

Question 2

What is papain

Answer 2

A type of protease that has low specificity (cleave any peptide bond)

Question 3

What is trypsin

Answer 3

A protien that helps break down dietary polypeptides

Higher specificity (cleaves after lys or arg only )

Question 4

What is thrombin

Answer 4

Highest specificity

Only cleaves after arg

Question 5

What is group specificity

Absolute specificity

Answer 5

Group: the enzyme cleaves any substrate with a certain FUCTIONAL group

Absolute: the enzyme has only one specific substrate (ex. Lactase only cleaves lactose)

Question 6

What do enzymes do to the equilibrium of a reaction

Answer 6

They make it so that the same equilibrium point (amount of product) it reached

But the max amount is reached much faster when the enzyme is present so that the reaction is KINETICALLY favourable

Question 7

What is the equilibrium of a reaction

Answer 7

The forward and reverse reactions occur at the same rate and the concentration of the product is constant

Question 8

What is delta g in a spontaneous reaction

At equilibrium

Answer 8

Negative, exergonic

Delta g is 0, there’s no energy left for work

Question 9

What is delta G

Answer 9

Gibbs change in free energy

It’s independent of the path of transformation, it only looks at the change in energy from products to reactants

Tells us nothing about the rate of the reaction

Question 10

What are standard conditions

Answer 10

Delta g knot
1M
1atm (for gas)
298K

Question 11

What is the conversion of delta g for biochemistry

Answer 11

Delta g knot prime
PH Of 7

It’s found by measuring keq (the reactant over product at equilibrium)

When H is a reactant it’s concentration is 1M

Question 12

Spontaneous reactions are ___

Answer 12

Not instantaneous

Question 13

How do enzymes accelerate reactions?

Answer 13

They lower the activation NRG (G#) to overcome the activation energy barrier (energy taken to go from reactant to intermediate)

Question 14

How do enzymes lower the activation NRG

Answer 14

The stablize the transition state (the short lived intermediate between the substrate and the product)

X#

Question 15

Where does the energy come from to help lower the activation energy of a reaction

Answer 15

When the enzyme binds to the substrate and many weak interactions occur, free energy is released

This free energy is called binding NRG

Question 16

When do maximum binding energy occur

Answer 16

During the transitions state, when the enzyme is interacting with the transition state

Question 17

What maximizes the amount of binding energy

Answer 17

Only the correct substrate binding to the enzyme can maximize, so this involves specificity

Question 18

What are 5 feature of the enzymes active site

Answer 18

The residues forming the active site come from different positions in the protiens sequence but are brought close cause of the 3D shape

Takes up a small volume/amount of the total protien

Has a unique micro environment

The active site residues Form many weak instactions with substrates

The specificity of substrate binding depends on the specific arrangement of the atoms in the active site

Question 19

What are cofactors

Answer 19

Non protien compunds that bind to protiens and are needed for biological activity (enzyme activity)

Include coenzymes and metals

Question 20

What are coenzymes

Answer 20

Type of co factor that is made of vitamin derived organic molecules

Question 21

What are metals

Answer 21

Type of cofactor that are just metals the help catalyze

Question 22

What are enzymes with cofactor called

Without

Answer 22

Holoenzyme

Apoenzyme

Question 23

What is a prosthetic group

What is a cosubstrate

Answer 23

The cofactor binds very tightly to the enzymes, basically in there permanently

The cofactor binds to the enzymes and then is released after each reaction is complete (not permanent)

Question 24

What are examples of Coenzyme COfactor

Answer 24

Nad+ from vitamin B3 (niacin) Gets reduced to NADH

Can also be oxides from NADH to make NAD+

Ex. The NADH bind to pyruvate and lactate dehydrogenase (enzyme) to get oxidized and form lactate from pyruvate

Question 25

What do metal cofactors do

Answer 25

Ex. Zinc bind to water and decreases it pka so it can deprotonated at ph 7

Then to o- of the water attacks co2 and makes carbonic acid

This all wouldn’t happen without the cofactor decreasing the pka

Question 26

What is the induced fit model of enzymes

Answer 26

The enzymes active site changes to be complementary to the substrate after it has binds (molds around it like playdoh)

Question 27

What is the lock and key model

Answer 27

The enzyme and substrate are already a perfect fit for each other , not moulding or reshaping occurs

Outdated model