Enzymes (part one) Flashcards

1
Q

Protein catalysis of biologic origin which enhances the rates of biochemical reactions at a rate as to be compatible with life

A

Definition of enzymes

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2
Q

Five general properties of enzymes

A
  1. Not altered or consumed during the reaction
  2. Only small amounts of enzyme are required
  3. Accelerate the speed at which a chemical reaction reaches equilibrium, but do not alter the equilibrium constant
  4. Each enzyme is highly specific for a given reaction
  5. Enzymes act by lowing the activation energy
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3
Q

Occurs when the 3-D structure starts to uncoil. Caused by

A

Denaturation

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4
Q

High or low cause denaturation of enzymes

A

Effect of temperature and pH

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5
Q

Non-protein compounds required by some enzymes to make them active

A

Cofactor

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6
Q

Inorganic cofactor is known as…?

A

Activator

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7
Q

Organic cofactor is known as…?

A

Coenzyme

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8
Q

Complete cofactor: enzyme complex

A

Holoenyme

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9
Q

Bound cofactor

A

prosthetic group

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10
Q

Protein portion of the enzyme

A

apoenzyme

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11
Q

A unique sequence and orientation of amino acids to form a pocket or groove that provides for the enzyme’s specificity for only a unique substrate

A

Active site

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12
Q

A region other than the active site where a separate compound reacts, altering the shape of the active site, altering its fit with the substrate; is used to regulate enzyme activity

A

Allosteric site

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13
Q

Different physical forms of an enzyme that all catalyze the same reaction. These differences allow isoenzymes to be separated, identified, and qualified

A

Isoenzymes

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14
Q

The quantity of enzyme that will catalyze the reaction of one micromole of substrate per minute under defined conditions

A

International unit

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15
Q

Amount of enzyme that catalyzes with a reaction rate of one mole/ second

A

Katal

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16
Q

The rate of enzymatic activity increases as the concentration of substrate increased until the maximum velocity of the reaction is achieved. This max is called the _______?

A

Vmax

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17
Q

one half of the vmax ***

A

Km

18
Q

List examples of activators (inorganic cofactors) and coenzymes (organic cofactors)

A

Inorganic: Zn2+, Fe2+, Cu2+, Mg2+, Mn2+
Organic: NAD+, NADH, NADP+, NADPH, Pyrixodal-5-phosphate

19
Q

Why is enzyme activity, rather than enzyme concentration, is measured in the laboratory

A

The amount of the enzyme is so small that it is difficult to devise assays that are sensitive enough. Instead, the rate of product formed or amount of substrate consumed during reaction is measured.
More enzyme that is present, the faster the reaction proceeds.

20
Q

Initial period when enzyme and substrate are first mixed, but no product is formed yet, so there is no detectable change in absorbance

A

Phases of an enzymatic reactions:

- lag phase

21
Q

Rate of product formed is linear with time, so reaction follows Beer’s Law

A

Phases of an enzymatic reactions:

log phase

22
Q

No change in absorbance b/c there is no substrate left to be converted to product. Rate of reaction is dependent on substrate concentration not enzyme concentration.

A

Phases of an enzymatic reactions:

- depletion phases

23
Q

Why should enzyme measurements should be made during the log phase

A

It corresponds to zero order kinetics! It follows Beers Law so it is an accurate measurement

24
Q

For a typical enzyme measurement curve, how are the axis labeled?

A

Y axis: Change in Absorbance

X axis: Time (seconds)

25
Q

Enzyme Curve Zero order kinetics

  • Define
  • Where on graph
A
  • The rate of the reaction is independent of reactant (substrate)
  • Corresponds to Log (linear) phase on the graph
26
Q

Enzyme curve First order kinetics

  • Define
  • Where on graph
A
  • rate of reaction is proportional to reactant (substrate)

- corresponds with the substrate depletion phase of the curve

27
Q

Reaction rate methods:

Kinetic

A

?

28
Q

Reaction rate methods:

Multipoint

A

?

29
Q

Reaction rate methods:

Continuous monitoring

A

?

30
Q

Michaelis-Menten curve:

  • Zero Order kinetics
    - Where on curve
A

At the end of the curve when it starts to flatten out

31
Q

Michaelis-Menten curve:

  • First Order kinetics
    - Where on curve
A

At the beginning of the curve were it is increasing

32
Q

Michaelis-Menten curve:

How are the axis labeled?

A

Y-axis: V, initial reaction rate (mol L-1 s-1)

X-axis: [S], concentration of substrate (mol L-1)

33
Q

Michaelis-Menten curve:

Vmax and Km on the curve

A

Vmax: Highest point curve goes
Km: half way up the Vmax

34
Q

Six factors that which influence enzymatic activity

A
  1. Enzyme concentration
  2. Substrate concentration
  3. Temperature
  4. pH
  5. Presence of cofactors
  6. Presence of inhibitors
35
Q

ESSAY
Plasma-specific enzymes
-Definition

A

Are expected to be in higher concentration in blood because they function there (ex: coagulation factors)

36
Q

ESSAY
Non-plasma-specific enzymes
-Definition

A

Have no known function in plasma; have functions in tissue (cellular metabolism, etc) (ex: LD or CK)

37
Q

ESSAY
Plasma-specific enzymes
-expected relative plasma and tissue concentrations

A

?

38
Q

ESSAY
Non-plasma-specific enzymes
-expected relative plasma and tissue concentrations

A

?

39
Q

ESSAY

Two GENERAL mechanisms for increased (enzyme)

A
  1. Increased in the rate of enzyme release into the bloodstream
  2. Increase in the rate of production of an enzyme
40
Q

ESSAY

Seven specific causes of cell damage or death

A
  1. Hypoxia
  2. Chemicals and Drugs
  3. Physical Agents
  4. Microbiological Agents
  5. Immune mechanisms
  6. Genetic Defects
  7. Nutritional Disorders
41
Q
  • ESSAY*

- Two SPECIFIC causes of increased enzyme production

A
  1. Enzyme induction (via drugs, alcohol, or other agents)

2. Proliferation of cells that produce that enzyme (cancer)

42
Q

List five physiological factors which affect enzyme reference ranges

A
  1. sampling time
  2. Age
  3. Sex
  4. Race
  5. Exercise (lack or and excessive)