CHAPTER 6: ENZYME PROTEINS

Question 1

TRUE OR FALSE: Catalysts are not consumed in a chemical reaction, they simply facilitate it.

Answer 1

TRUE

Question 2

Generally globular proteins (water-soluble proteins)
○ Ribozymes: RNA-based biological catalysts
○ Most effective catalysts known to man as it can
increase the rate of a reaction by a factor up to ____

Answer 2

Enzymes: 10(20)

Question 3

determines if a reaction will
occur naturally (spontaneously).

Answer 3

Thermodynamics

Question 4

determines if a
reaction is spontaneous. the difference between energies of reactants and products under standard conditions.

Answer 4

Standard Free Energy Change (Gº) –

Question 5

is the amount of energy
needed to initiate a chemical reaction.

Answer 5

Activation Energy (ΔG ‡

Question 6

Relationship between rate and energy of enzyme

Answer 6

uncatalyzed (no enzyme) = more activation energy= slower to reach the transition state

Question 7

TRUE OR FALSE:The higher the activation energy, the faster the reaction to reach completion.

Answer 7

FALSE: faster

Question 8

Reaction rate is independent of
the molar concentration of the
reactants.

Answer 8

ZEROTH: Rate = k
Rate = k[A]
0
= k(1)
= k

Question 9

Reaction rate is dependent on the concentration of A and B

Answer 9

Second k = (A) (B) or k (A) 2

Question 10

Reaction rate is dependent on the concentration of one reactant

Answer 10

First

Question 11

is the reactant of an enzyme-catalyzed reaction.
Substrates bind with an enzyme’s active site with _______

Answer 11

substrate

noncovalent interactions - Hydrogen bonds
Ionic interactions
Van der Waals forces
Hydrophobic interactions

Question 12

is the part of an enzyme to which the substrate binds to and where the reaction take place.

Answer 12

active site

Question 13

Differentiate the two enzyme binding process

Answer 13

induced fit- nagccompromise
locke and key- super fit

Question 14

Michaelis menten mechanism

Answer 14

E+S = ES = EP (k1,k-1 and k2)

Question 15

inverse measure of the affinity of the enzyme for the substrate

Answer 15

Km

Lower km= mhigher affinity (ability of enzyme to bond w substrate)

Question 16

What are the three enzyme mechanism

Answer 16

Ordered, Random, Pingpong

Question 17

What is the Michaelis Menten equation(make it linear):

Answer 17

1/V= Km + (S)/ Vmax (S)

If not linear and nakahyperbola, pagbaliktarin m lng yn

Question 18

number of moles of substrate that react to form
product per mole of enzyme per second.

Answer 18

turnover number

Question 19

Examples of Enzyme catalyzed reaction

Answer 19

Chymotrypsin

Aspartate Transcarbamoylase

Question 20

What is chymotrypsin

Answer 20

It facilitates the hydrolysis of peptide bonds of aromatic side chains (Phe, Tyr, Trp) and ester bonds

Question 21

What is Aspartate Transcarbamoylase

Answer 21

It facilitiates the reaction of Carbamoylase and Aspartate in forming Carbamoyl Aspartate

Essential for formation of CTP and UTP for pyrimidine biosynthesis in DNA and RNA

Question 22

Small KM:

Answer 22

High affinity, because only a small
amount of substrate is required to
half-activate enzymes.

Question 23

Large KM:

Answer 23

Low affinity, because a large
amount of substrate is needed in order to
half-activate enzymes.

Question 24

reflects the efficiency of
an enzyme in converting substrates to products.

Answer 24

Maximum Velocity, Vmax

,

Question 25

a graphical method for analyzing the kinetics of enzyme-catalyzed reactions.

Answer 25

Lineweaver Burk plot

Question 26

are substances that decrease the rate of an enzyme-catalyzed reaction

Answer 26

Inhibitors

Question 27

Type of reversible inhibitors (bind to the enzyme and subsequently be released, leaving the enzyme in its original composition

Answer 27

Competitve, Uncompetitive, NOncompetitive, irreversible

Question 28

Competitive INhibitor

Answer 28

Km= increase Vmax= doesn't change Both lines intersect at the same y-intercept (don't change) but have different x-intercepts and slope, changes)

Question 29

Inhibitor resembles the substrate in terms of size and charge distribution /substrate analog). Binds to the active site by forming non-covalent interactions.

Answer 29

Competitive

Question 30

Inhibitor binds to another part of the enzyme other than the active site. ● May or may not resemble the substrate.

Answer 30

Noncompetitive

Question 31

Noncompetitive

Answer 31

●KM unchanged ● Decreased VMAX ● Both lines have the same x-intercept but plot for inhibited enzymes has greater y-intercept. ●slope and y changes ● x is unchanged

Question 32

an inhibitor binds to an allosteric site, affecting the enzyme's activity regardless of whether the substrate is bound. It cannot be overcome by increasing substrate concentration.

Answer 32

noncompetitive inhibition

Question 33

covalently bind to the enzyme, permanently inactivating it.

Answer 33

Irreversible inhibitors

Question 34

Lines intersect at the y-axis.

Answer 34

Competitive Inhibition:

Question 35

Lines intersect at the x-axis.

Answer 35

Noncompetitive Inhibition:

Question 36

Uncompetitive

Answer 36

Km decreased VMAX decreased ● Lines are parallel

Question 37

INhibitor binds to ES complex but not to free enzymes

Answer 37

Uncompetitive

Question 38

Binding of 1 does not affect binding of substrate and vice versa

Answer 38

mixed noncompetitive inhibition

Answer 39

K m : The Michaelis constant may increase or decrease, depending on the relative affinities of the inhibitor for the enzyme and the enzyme-substrate complex. Vmax : The maximum reaction rate decreases because the inhibitor reduces the effective concentration of the enzyme available for catalysis.