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anatomy > BIOCHEM - Enzyme > Flashcards

BIOCHEM - Enzyme Flashcards

1
Q

organic catalysts where their main function is to speed up metabolic functions in the body.

A

Enzymes

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2
Q

reaction formula for enzyme

A

A + B ⇌ P+ Q

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3
Q

formula for forward reaction

A

A + B to P+Q

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4
Q

formula for backward reaction

A

P + Q to A+B

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5
Q

symbol is used to denote an equilibrium;

means the forward reaction is equivalent to backward reaction.

A

⇌

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6
Q

what does A + B ⇌ P+ Q mean

A

There’s no net of formation of either A+B and P+Q; hence, they are in equilibrium.

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7
Q

symbol used to denote a net forward reaction.

A

→

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8
Q

formula that shows The predominant is the forward reaction or the formation of P+Q.

A

A+B → P+Q

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9
Q

portion of the total energy in the system that is available for work

A

Free energy, ∆G

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10
Q

formula for free energy (Gibbs free)

A

∆G = ∆H - T∆S

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11
Q

∆G = ∆H - T∆S meaning:

A

∆G (Gibbs free) is equal to ∆H (Enthalpy) total internal energy MINUS Temperature (T) multiplied by Entropy (∆S)

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12
Q

“heat”, equal to the total change in the
internal energy of the system

A

Enthalpy, ΔH

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13
Q

extent of disorderliness/randomness of the
system;

becomes maximum(100%) as equilibrium (forward reaction is equal to the reverse reaction) is approached

A

Entropy, ΔS

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14
Q

∆G = 0 means

A

Equilibrium, no net change takes place

the forward and backward reactions are equal

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15
Q

“Exergonic”, spontaneous

Product of temperature and entropy is bigger than enthalpy. It gives off energy

A

∆G ‹ 0 (negative)

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16
Q

“Endergonic”, nonspontaneous

Takes in energy

A

∆G › 0 (positive)

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17
Q

The downhill movement of the ball is considered ___________ because the starting ball would have a higher energy compared to the end ball.

A

spontaneous

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18
Q

the energy that must be overcome in order for the reaction to proceed
regardless if it is spontaneous (exergonic) or nonspontaneous (endergonic)

A

activation energy

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19
Q

the energy of the reactants is higher than the energy of products

A

exergonic (energy release)

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20
Q

activation energy for reaction proceeds rapidly

A

low activation energy

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21
Q

activations energy that cause slow reaction

A

high activation energy

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22
Q

between endergonic and exergonic reactions, which among the two energies of their reactants are far from the activation energy?

A

Endergonic, because the initial energy of the reactant in exergonic is already high enough that it only needs a small amount of energy
to reach the activation energy as compared to the endergonic reaction.

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23
Q

reactants are at a lower free energy level than the products

A

endergonic

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24
Q

energy of the products is lower, and the difference in the energy of reactants and products are being release

A

exergonic reaction

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25
Q

If the reactants are at a lower free energy level than the products

A

endergonic

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26
Q

If the free energy level of the reactant is higher than the product

A

exergonic (spontaneous) (energy release)

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27
Q

in exergonic reaction but the energy release is in the form of HEAT.

A

Exothermic

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28
Q

endergonic reactions that would take up heat

A

endothermic

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29
Q

FACTORS AFFECTING REACTION RATES:

A
  1. TEMPERATURE
  2. REACTANT CONCENTRATION
  3. PRESENCE OF CATALYSTS (e.g Enzymes)
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30
Q

If we increase the temperature, the ________ will become faster.

A

reaction rate

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31
Q

Increase in temperature would result to increase in __________________

The molecules will move faster.

A

kinetic energy

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32
Q

energy during motion

A

Kinetic energy

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33
Q

in a chemical reaction, the products will be formed if the molecules of the substrate will collide.

A

Circulation Theory

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34
Q

One way of increasing the collision in between your substrate molecules will be to increase the _________

A

movement of the molecules

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35
Q

increase in the concentration of the substrate, would increase the ______ in between the molecules

  • Thereby, facilitating in the formation of the product
A

collision

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36
Q

Ratio of the concentrations of products and reactants

A

Keq, Equilibrium Constant

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37
Q

It gives as an idea whether the favored reaction occurring is the forward or the backward reaction. (If it is the formation of the products or formation of the reactants is favored).

A

Keq, Equilibrium Constant

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38
Q

formula of Keq, Equilibrium Constant

A

Products [P] [Q] over Reactants [A] [B]

(molar concentrations in the bracket)

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39
Q

speeds up the reaction

A

catalysts

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40
Q

will lower the activation energy (pile of stones in the figure) thereby, facilitating the reaction

A

enzymes

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41
Q

Proteins that would speed up chemical reactions and are not used up during chemical reactions they catalyzed

A

ENZYMES

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42
Q

Two steps for enzyme to catalyze:

A
  1. They must bind to substrate.
  2. They would facilitate the catalysis known as the catalytic step.
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43
Q

During the ___________, bonds are being formed or broken.

  • Products will then be produced
A

catalytic steps

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44
Q

steps on enzyme-substrate binding:

A

a. Substrate Binding (enzymes will bind to the substrate
b. Enzyme-Substrate Complex (catalytic step will occur)
c. Product is formed
d. Product detaching from the enzyme

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45
Q

Portion of enzyme which folds to precisely fit the contours of a substrate via weak electrostatic interactions & facilitates bond reactivity

A

Active site

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46
Q

Portion of the enzyme where it directly binds to the substrate

A

Active site

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47
Q

Active sites are _________: it can only bind certain type of substances

  • examples are the enzymes that
    specifically bind only to hexoses, or
    glucose, etc.
  • e.g., if it binds to glucose, it could not
    bind to another monosaccharide
A

specific

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48
Q

THEORIES ON ENZYME-SUBSTRATE BINDING:

A
  1. Lock-and-Key Model
  2. Induced fit Model
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49
Q

The enzyme’s active site fits the substrate perfectly.

  • When the enzyme approaches the substrate, there is already an initial perfect fit between the substrate and the enzyme’s active site.
A

Lock-and-Key Model

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50
Q

This explains why enzymes are specific when it comes to substrate.

If this enzyme is acting on a protein, any other molecule that isn’t a protein (e.g., Carbohydrate) would not fit the active site and therefore would not be acted upon by the enzyme.

A

Lock-and-Key Model

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51
Q

limitation of Lock-and-Key Model:

A

enzymes are very rigid,
1 enzyme: 1 substrate

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52
Q

This is far from the truth because enzymes are proteins and proteins are FLEXIBLE molecules.

Although they are specific when it comes to substrate, they are not really that specific. As long as the substrates are interrelated to one another, enzymes can still act upon it

A

Lock-and-Key Model

53
Q

if we follow this model, it would mean that your enzyme should be rigid, should not change its conformation.

  • Aside from that, there are enzymes that can bind to several substrates (e.g., hexoses can bind to glucose, galactose, and fructose)
A

Lock-and-Key Model

54
Q

This is NOT the best model to explain the enzyme-substrate binding!

A

Lock-and-Key Model

55
Q

Enzyme-substrate binding will be explained by:

A

Induced fit Model

56
Q

Initially, there is no perfect fit between the active site and the substrate.

A

Induced fit Model

57
Q

When the enzyme approaches the substrate, the substrate induces a change in the active site so complementarity will be achieved –

_____________ – eventually achieving a perfect fit

A

conformational change

58
Q

Modification of the lock-and-key model.

A

Induced fit Model

59
Q

the substrate can change the enzyme by inducing a conformational change in the _________

A

active site

60
Q

Also implies that the enzymes can change the substrate by acting on it and turning it to a product

A

Induced fit Model

61
Q

example of Induced fit Model

A

Proteases - Act on a variety of proteins. -Proteins are interrelated to one another structurally

62
Q

Only made up of protein.

A

SIMPLE ENZYMES

63
Q

Small, inorganic, metal ions that are required of some enzymes to activate them.
Metal ions: Cu, Mg, Mn, Fe

  • Usually located near the active site
    -Helps in binding to the substrate
A

CO-FACTORS

64
Q

Act as activators and/or inhibitors of activity

Example: Mg++ stabilizes the carbonyl oxygen in the phosphoenol pyruvate to allow the enzyme enolase to act on it; Mg++ participates in the catalytic activity.

A

CO-FACTORS

65
Q

Big, non-protein, organic molecules that are required of some enzymes to activate them.
- Function same with the cofactors.
- Activate or inhibit enzymes.
- Not metallic ions

A

CO-ENZYME

66
Q

Participates in binding to the substrate.

Binds to the active site to prepare the active site for substrate binding.

A

CO-ENZYME

67
Q

CO-ENZYME Help catalyze reactions by:

A
  • Donate/accept electrons
  • transfer group
  • Form/break covalent bonds
  • Provide functional groups
68
Q

Common co-enzymes:

A
  • Lipoic acid
  • NAD/NADP, FAD
  • CoASH
  • Vitamins
69
Q

Lipoic acid :

A

Decarboxylate alpha-keto acid

70
Q

NAD/NADP, FAD :

A
  • Redox reaction
  • Transfer of electrons
  • Dehydrogenation
  • Transfer of H+
71
Q

CoASH:

A
  • Kreb’s Cycle
  • Beta oxidation
72
Q

Vitamins:

A
  • The body needs vitamins such as ascorbic acid, cyanocobalamin and folic acid.
  • By themselves, they do not provide energy but instead help unlock energy by acting as co enzymes for some metabolic reactions
73
Q

The entire enzyme together with all the necessary cofactor plus the protein portion.

● The complete enzyme

A

HOLOENZYME

74
Q

● Simple enzyme
● Taken out cofactor or coenzyme, only left with the protein
portion

A

APOENZYME

75
Q

There are certain cofactors or co-enzymes that are difficult to separate
from the protein portion of the enzyme because they are covalently
bound to the enzyme.

A

PROSTHETIC GROUPS

76
Q

example of PROSTHETIC GROUPS

A

Heme

77
Q

The structure shown here that is present not just in hemoglobin but in other
enzymes like catalase.

A

Heme

78
Q

Factors Affecting Enzyme Activity

A
  1. Temperature
  2. pH
  3. Substrate concentration
79
Q

Enzymes are protein and extremes _________ can denatured enzymes

A

temperature

80
Q

as the temperature increases initially, the enzymatic activity increases but up to a certain point only, this point termed as _____________

A

optimal temperature

81
Q

The enzymatic activity in the human body is about ________.

More than that the enzymatic activity starts to inactivated or denatured

A

40

82
Q

Also have an optimum pH

However, each enzymes have their own specific _________

A

optimum pH

83
Q

pepsin optimum pH is around pH _____
(acidic)

A

pH 1

84
Q

and enzyme in small intestine optimum pH is around pH _____

A

pH 8

85
Q

Initially, if substrate concentration increases, the __________ will also increases

A

enzymatic activity

86
Q

substrate concentration and enzymatic activity is __________

A

directly proportional

87
Q

once reached the maximum velocity,
the enzymatic activity will no longer increase
because the enzymes are already occupied

A

saturated

88
Q

A graph that shows the relationship between the concentration of a substrate and the rate of the corresponding enzyme-controlled reaction.

A

Michaelis-Menten curve

89
Q

Initially, as you increase the substrate
concentration it is directly proportional to the reaction rate, up to a certain point.

When the enzyme is saturated, further increasing the substrate concentration leads to _____________.

A

slower reaction rate

90
Q

Michaelis-Menten curve [S]

A

concentration of substrate (mol L-1)

91
Q

Michaelis-Menten curve [V]

A

initial reaction rate (mol L-1 s-1)

92
Q

relationship between initial reaction rate V and substrate reaction rate S

A

Michaelis-Menten equation

93
Q

Important Parameters in Michaelis-Menten Equation:

A

Vmax
Substrate concentration [S]
Vi - reaction rate
Km

94
Q

○ Maximum velocity of the reaction
○ Never be reach by the chemical reaction
○ ½ Vmax or 50% maximum velocity

A

Vmax

95
Q

reaction rate

A

Vi

96
Q

Michaelis constant

A

Km

97
Q

substrate concentration at 50% of maximum velocity Vm

A

Michaelis constant Km

98
Q

How to determine the Km Michaelis constant?

A

get 50% of Vmax plot it against the x-axis or the substrate concentration

99
Q

A point/substrate concentration wherein the
reaction is at 50% of the maximum velocity

A

Michaelis constant Km

100
Q

the amount of Km if it has low affinity
to the substrate.

Because high substrate concentration results in low saturation

A

high Km

101
Q

if the Km is low, the affinity is ______________

at smaller substrate concentration, it immediately reach 50%

50% of the enzyme are already bound

A

high

102
Q
  • Independent of the reactant concentration
  • the reaction rate is constant regardless of how high or low the reactant concentration is.

● Fixed reaction rate of zero reaction rate

A

Zero reaction rate

103
Q

Even if we increase the reactant concentration, there is a corresponding increase in the reaction rate

The reaction rate is dependent on the reactant concentration. the more the reactants the more faster the reaction rate

A

First order reaction

104
Q

there is a Direct, proportional relationship between reactant concentration and enzyme reaction rate (if we the increased reaction concentration the reaction rate increases)

A

First order reaction

105
Q

Plot the reaction of the substrate concentration against the reaction rate. What is obtained is a ____________.

It is a combination of the zero order and the first order

A

hyperbolic curve

106
Q

Initially, it follows the first order reaction, mixed, then zero order kinetics becoming independent of the reactant concentration upon reaching the Vmax

A

Michaelis-Menten Curve

107
Q

Enzyme with ____________ Km is easily saturated because of its high affinity

A

Low Km

108
Q

high affinity enzyme get the substrate resulting into:

A

easy saturation

109
Q

the Vmax of low Km high affinity is:

A

slower compared to high Km low affinity

110
Q

Michaelis Menten curve converted into linear graph:

A

1/Vi = (Km/Vmax)1/[S] + 1/Vmax

111
Q

a double reciprocal (fraction) of each point of Michaelis Menten curve making it into linear function called ___________

A

Lineweaver-Burke plot

112
Q

Y= mx + b in algebra means:

A

y= value of Y in Y-axis
m= slope
x= value of x in x-axis
b = point of intersection (y-intercept)

113
Q

In Lineweaver Burk plot, Y= mx + b means:

A

Y = reciprocal of initial velocity (1/Vi)
m = slope (Km/Vmax)
x = 1/[S]
d = 1/Vmax

X intercept = (-1/km) or negative reciprocal of km

114
Q

is important because it gives an idea of the
different mechanisms of enzyme inhibitors.

A

Lineweaver Burke plot

115
Q

Enzyme inhibitors:

A

Competitive inhibitor
noncompetitive inhibitor
Uncompetitive inhibitor

116
Q

1/Vmax is not affected. Constant. (down in the point of intersection between the two lines)

X intercept (-1 / Km) is increased (from negative 1/3 to negative 1/4)

A

Competitive inhibitor

117
Q

decrease the affinity of the enzyme to the substrate without affecting the overall maximum velocity Vmax of the reaction

increase Km

A

Competitive inhibitor

118
Q

Reversible inhibitor because when further increase the amount of substrate, the inhibitor can be bumped off from
the active site.

A

Competitive inhibitor

119
Q

The substrate and the inhibitor compete for the same binding site which is the active site.

If it is the substrate that binds to the enzyme, well and good.
if it is the inhibitor that binds the enzyme, this turns the enzyme inactive. “banked off”

this is a ___________ type of inhibition

A

reversible type of inhibition

120
Q

in competitive inhibition, inhibitors often resemble the substrate structurally, they
are said to _____________.

A

molecular analogous

121
Q

Affinity is not affected
-1 / Km is constant
Vmax is decreased

A

Noncompetitive inhibitor

122
Q

It lowers down the overall reaction rate but it will not affect the affinity of the substrate to the enzyme

A

Noncompetitive inhibitor

123
Q

Noncompetitive inhibitor are not competing with the same binding site.

the substrate binds to the active site, the inhibitor binds to another site called the ______________________ (site other than the
active site)

A

allosteric site

124
Q

both EI and EIS complexes are enzymatically inactive

Allosteric site causes a conformational change to the active site inhibiting the substrate from binding to the active site
causing the reaction rate to decrease

A

Noncompetitive inhibitor

125
Q

Occurs when the inhibitor binds only to the ES complex to form the EIS complex

Inhibition is irreversible

A

Uncompetitive inhibition

126
Q

Vmax decreased
Km decreased
increase the affinity of this substrate
to the enzyme

A

Uncompetitive inhibitor

127
Q

irreversible inhibitors:

A

Noncompetitive inhibitor
Uncompetitive inhibitor

128
Q
A

anatomy (15 decks)

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