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Chem 193 Biochemistry C3 > Enzymes > Flashcards

Enzymes Flashcards

1
Q

Characteristics of enzymes

A

➢ Lower the activation energy (Ea)
➢ Increase the rate of reaction
➢ Activity lost if denatured
➢ May contain cofactors such as metal ions or
organic (vitamins)

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2
Q

All catalysts share 3 basic properties:

A

a. Increases reaction rate by lowering Ea required.
b. Forms reversible complexes with substrate molecules
c. Changes the RATE at which the equilibrium is achieved, not the POSITION of the equilibrium

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3
Q

Have high substrate affinity and specificity.
Also, reusable. They are not
used up in the reaction.

A

Enzymes

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4
Q

usually a groove or
pocket that
accommodates the
intended substrate(s)
with high affinity

A

ACTIVE SITE

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5
Q

a molecule acted upon
by an enzyme

A

SUBSTRATE

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6
Q

binding that involves hydrogen
bonds, ionic bonds or
both, and are readily reversible

A

SUBSTRATE BINDING

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7
Q

Reactants need to
reach an intermediate
chemical stage called
the and overcome the EA barrier for
needed reactions to
occur.

A

transition state.

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8
Q

what overcome
the activation energy
barrier.

A

Catalysts

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9
Q

what do catalyst do to speed up reaction

A

lower activation energy

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10
Q
  • catalyzes Oxidation-reduction reactions
  • catalyzed the Transfer of functional group of molecules
  • catalyzed the Hydrolytic cleavage of molecules
  • catalyzed the Removal/Addition of a group of atoms to/from a double bond
  • catalyzed the Rearrangement of atoms within a molecule
  • catalyzed the Joining of 2 molecules to form a single molecule with ATP hydrolysis
A
  • Oxidoreductases
  • Transferases
  • Hydrolases
  • Lyases
  • Isomerases
  • Ligases
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11
Q

transfer amino groups

A

transaminases –

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12
Q

transfer phosphate groups

A

kinases

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13
Q

hydrolyze peptide bonds

A

proteases

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14
Q

hydrolyze lipid ester bonds

A

lipases

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15
Q

catalyzed the cleavage of C-C, C-O, C-N,
and other bonds by elimination, leaving
double bonds, and also adding groups to
double bonds.

A

Lyase

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16
Q

catalyze the movement of ions or
molecules across membranes or
their separation within
membranes.

A

Translocases

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17
Q

Series of four numbers that denote the class,
subclasses, sub-subclasses, and individual
entries to describe a particular enzyme.

A

International Commission on
Enzymes

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18
Q

The lock and key analogy is that the enzyme
is the lock and the substrate is the key.

A

lock and key model

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19
Q

Enzyme structure flexible, not rigid
Enzyme and active site adjust shape to
bind substrate

A

Induced fit model

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20
Q

Enumerate the catalytic process

A

STEP 1:
The random collision of a substrate molecule
with the active site results in it binding there
STEP 2:
Substrate binding induces a conformational
change that tightens the fit, facilitating the
conversion of substrate into products
STEP 3:
The products are then released from the active
site
STEP 4:
The enzyme molecule returns to the original
conformation with the active site available for
another molecule of substrate

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21
Q

Factors Affecting Enzyme
Action

A
  1. Environmental Conditions
  2. Cofactors And Coenzymes
  3. Enzyme Inhibitors
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22
Q

Different environmental condition that affects enzyme

A

Temperature
Substrate concentration
pH

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23
Q

Enzyme increases with temperature until it reaches the

A

Optimum temperature

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24
Q

Optimum temp in Human enzyme and Bacterial enzyme

A

37°C, 75°C

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25
Q

Increasing _________ concentration
increases the rate of reaction

A

substrate

26
Q

When does the maximum activity reached when we add substrate concentration to increase the rate of reaction?

A

when all of enzyme combines with substrate

27
Q

Optimum pH is

A

7

28
Q

Substances that are sometimes needed
for proper enzymatic activity, often
because they function as electron
acceptors

A

Cofactors and coenzymes

29
Q

usually metal ions or small organic molecules called
coenzymes.

A

Prosthetic enzymes

30
Q

small molecules needed in
catalytic activity

A

Cofactors

31
Q

derived in vitamins

A

coenzymes

32
Q

In the oxygen circulation through the blood, what is the cofactor used?

A

Iron

33
Q
  • Molecules which slow down or prevent an enzyme reaction
  • Cause a loss of catalytic activity
  • Change the protein structure of an
    enzyme
A

Inhibitors

34
Q

Inhibitors bind the enzyme very
tightly; generally form covalent
bonds causing permanent loss of
catalytic activity and are generally
toxic to cells

A

Irreversible inhibitors

35
Q

inhibitors bind enzymes non
covalently; can dissociate with the
enzyme

A

Reversible inhibitors

36
Q

Inhibitor that binds at the active
site

A

Competitive

37
Q

Inhibitor that binds at another site
on enzyme

A

Noncompetitive

38
Q

As substrate concentration increases in competitive inhibition, the substrate molecules outnumber the inhibitor so

A

the reaction rate reaches the maximum

39
Q

A high substrate concentration is added in noncompetitive inhibition, this result to

A

no change in the reaction rate

40
Q

describes the quantitative
aspects of enzyme catalysis and the rate of
substrate conversion into products

A

enzyme kinetics

41
Q

are measured over a brief
time, during which the substrate concentration
has not yet decreased enough to affect the rate
of reaction.

A

initial reaction rates

42
Q

the rate of change in
product concentration per unit time

A

Initial reaction velocity (v)

43
Q

Initial reaction velocity (v), the rate of change in
product concentration per unit time, depends on
the

A

Substrate concentration [S]

44
Q

The Michaelis-Menten equation revealed that the initial velocity of the reaction is roughly proportional to [S] at ___

A

at very low [S],

45
Q

The Michaelis-Menten equation revealed that the initial velocity of the reaction is independent of variation in [S]. This state happens at

A

At very high [S],

46
Q

is the velocity at saturating
substrate concentrations

A

Vmax

47
Q

Michaelis-Menten equation

A

v = Vmax [S] / KM + [S]

48
Q

The half of Vmax is

A

Km

49
Q

Km is a useful indicator of for the

A

affinity of an
enzyme for the substrate

50
Q

Note that an enzyme with a low Km has a ____ affinity
for the substrate

A

high

51
Q

is an upper limit determined by the time required for the actual catalytic reaction and how
many enzyme molecules
are present.

A

Vmax

52
Q

The only way to increase
Vmax is to

A

increase enzyme
concentration.

53
Q

x-axis and y-axis in Michaelis graph

A

x = initial rate, V
y = substrate concen

54
Q

The ______the Km value for a given enzyme and
substrate, the lower the [S] range in which the
enzyme is effective.

A

lower

55
Q

a measure of the potential
maximum rate of the reaction

A

Vmax

56
Q

x-axis and y-axis in Lineweaver-Burk plot

A

x = 1/Vo
y = 1/[S]

57
Q

Visualize the Lineweaver-Burk plot, point out the location of -1/Km, Km/Vmax, and Vmax

A

use your imagination gurl

58
Q

In competitive inhibition, what happen to Km and Vmax

A

Vmax is unaffected
KM is increased

59
Q

In noncompetitive inhibition, what happen to Km and Vmax

A

Vmax is decreased
KM is unaffected

60
Q

In uncompetitive inhibition, what happen to Km and Vmax

A

Vmax is decreased
KM is decreased

61
Q

Once slope and y-intercept is calculated, what to solved first and how? What to do next?

A

Solved for Vmax = 1/y-intercept
Then, Solved for Km = slope/Vmax

Chem 193 Biochemistry C3 (4 decks)

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