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BIO CHEM LEC > Enzyme part 2 > Flashcards

Enzyme part 2 Flashcards

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1
Q

What are the three types of SPECIFICITY OF ENZYMES:

A

a) Stereochemical specificity
b) Reaction specificity
c) Substrate specificity

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2
Q

_____________ only one of the isomers which acts as a substrate for an enzyme action
(e.g. succinic dehydrogenase while acting on succinic acid will give only __________and not malic acid which is its isomer)

A

Optical specificity only one of the isomers which acts as a substrate for an enzyme action
(e.g. succinic dehydrogenase while acting on succinic acid will give only fumaric acidand not malic acid which is its isomer)

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3
Q

___________ is due to apoenzyme part of holoenzyme, while the_________ is due to the coenzyme or prosthetic group.

A

Stereospecificity is due to apoenzyme part of holoenzyme, while the reaction specificity is due to the coenzyme or prosthetic group.

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4
Q

A substrate can undergo many reactions, but in a
___________, one enzyme can catalyze only
one of the various reactions.
(e.g. oxaloacetic acid undergoes several reactions, but each reaction is catalyzed by its own separate enzyme which catalyzes only that reaction and none of the others)

A

A substrate can undergo many reactions, but in a
reaction specificity, one enzyme can catalyze onlyone of the various reactions.
(e.g. oxaloacetic acid undergoes several reactions, but each reaction is catalyzed by its own separate enzyme which catalyzes only that reaction and none of the others)

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5
Q

2 types of Substrate Specificity

A

Absolute Specificity
Relative Specificity

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6
Q

It is comparatively rare such as urease which
catalyzes hydrolysis of urea

A

Absolute specificity

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7
Q

Relative specificity – divided as

A

Group Specificity
Bond Specificity

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8
Q

Examples of group specificity are:

A

-trypsin
-chymotrypsin.

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9
Q

________hydrolyzes the residues of only lysine
and arginine

A

Trypsin hydrolyzes the residues of only lysine and arginine

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10
Q

____________ hydrolyzes residues of only aromatic amino acid

A

chymotrypsin hydrolyzes residues of only aromatic amino acid

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11
Q

FACTORS AFFECTING ENZYME ACTION

A

1.Effect of Temperature
2. Effect of pH
3. Effect of enzyme concentration
4. Effect of product concentration
5. Effect of substrate concentration
6. Effect of activators and coenzyme
7. Effect of modulators and inhibitors
8. Effect of time

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12
Q

_______________
- enzyme is most active on its optimum temperature
- temperature increases the total energy of the chemical system with the result the activation energy is increased
- enzyme activity decreases when the temperature of reaction is below or above the optimum temperature
- increase in temperature also causes denaturation of enzymes

A

Effect of Temperature

  • enzyme is most active on its optimum temperature
  • temperature increases the total energy of the chemical system with the result the activation energy is increased
  • enzyme activity decreases when the temperature of reaction is below or above the optimum temperature
  • increase in temperature also causes denaturation of enzymes
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13
Q

_____________
- enzymatic reaction depends on the pH of the medium
- optimum pH is _______
- hydrogen ions in the medium may alter ionization of active site or substrates (ionization is a requirement for ES complex)
- pH may influence separation of coenzyme from
holoenzyme complex

A

Effect of PH
- enzymatic reaction depends on the pH of the medium
- optimum pH is 4-9
- hydrogen ions in the medium may alter ionization of active site or substrates (ionization is a requirement for ES complex)
- pH may influence separation of coenzyme from
holoenzyme complex

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14
Q

______________________
- enzymatic reaction is directly proportional to the enzyme concentration

A

Effect of enzyme concentration
- enzymatic reaction is directly proportional to the enzymeconcentration

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15
Q

___________________
- products formed as a result of enzymatic reaction may accumulate, and this excess of product may lower the enzymatic reaction by occupying the active site of the enzyme
- it is also possible that under certain conditions of high concentration of products, a reverse reaction may be favored forming back the substrate

A

Effect of product concentration
- products formed as a result of enzymatic reaction may accumulate, and this excess of product may lower the enzymatic reaction by occupying the active site of the enzyme

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16
Q

__________________
- reaction is directly proportional to the substrate
concentration, but only true up to a certain
concentration after which the increasing
concentration of substrate does not further increase the velocity of the recation

A

Effect of substrate concentration

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17
Q

____________________
- certain enzymes is dependent of metal ion activators and coenzymes

A

Effect of activators and coenzyme
- certain enzymes is dependent of metal ion activators and coenzymes

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18
Q

_____________
- Whenever the active site is not available for binding of-the substrate, the enzyme activity may be reduced.
- Substances which stop or modify enzymatic reaction are inhibitors and modulators which can adversely affect the rate of enzymatic reaction

A

Effect of modulators and inhibitors
- Whenever the active site is not available for binding of the substrate, the enzyme activity may be reduced.
- Substances which stop or modify enzymatic reaction are inhibitors and modulators which can adversely affect the rate of enzymatic reaction

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19
Q

___________
- The time required for completion of an enzyme
reaction increases with decreases temperature from its optimum.
- Under the optimum conditions of pH and
temperature, time required for enzymatic reaction is less

A

Effect of time
- The time required for completion of an enzyme
reaction increases with decreases temperature from its optimum.
- Under the optimum conditions of pH and
temperature, time required for enzymatic reaction is less

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20
Q

The part of the enzyme that binds with the substrate.

A

Active Site

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21
Q

Characteristics of the Active Site

A
  • Enzyme active sites are pocket or cleft in the surface of the enzyme.
  • The shape of the active site is complementary to theshape of the substrate. (or Fits nearly into the active site of the enzyme)
  • An enzyme attracts and holds its substrate by weak, non-covalent interaction.
  • The conformation of the active site determines the specificity of the enzyme because only the substrate that fits into the active site will be used in a reaction
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22
Q

What are the 2 Models Used in Enzyme

A

• LOCK-AND-KEY MODEL
• INDUCED FIT MODEL

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23
Q

Who created the LOCK-AND-KEY MODEL

A

Emil Fischer in 1894.

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24
Q

•INDUCED FIT MODEL
By ________in _____

The induced-fit theory assumes that the substrate plays a role in determining the final shape of an enzyme and that the enzyme is partially flexible

A

•INDUCED FIT MODEL
By Daniel E. Koshland, Jr. in 1958

The induced-fit theory assumes that the substrate plays a role in determining the final shape of an enzyme and that the enzyme is partially flexible

25
Q

True or False

Is only the proper substrate is capable of inducing the proper aligning of the active site?

A

True

26
Q

What are the 4 Types of catalytic mechanisms that enzymes employ;

A

-Covalent Catalysis
-Catalysis by Proximity and orientation
-Acid-base catalysis
-Metal ion catalysis

27
Q

______rates of enzyme-catalyzed reactions can be
decrease by a group of substances called
________

A

ENZYME INHIBITION rates of enzyme-catalyzed reactions can be decrease by a group of substances called inhibitors

28
Q

a molecule that sufficiently resembles an enzyme substrate in shape and charge distribution that it can compete with the substrate for occupancy of the enzyme’s active site

A

Competitive enzyme inhibitor

29
Q

it can be reduced by increasing
the concentration of the substrate.

A

Competitive inhibition

30
Q

a molecule that decreases enzyme activity by binding to a site on an enzyme other than the active site

A

noncompetitive enzyme inhibitor

31
Q

It Occurs when (II) binds only to the enzyme-substrate complex (ESES) and not free EE. One can hypothesize that on binding S, a
conformational change in EE occurs which presents a binding site for II. Inhibition occurs
since ESIESI can not form product. It is a dead
end complex which has only one fate, to return
to ESES.

A

Uncompetitive Inhibition

32
Q

a molecule that inactivates enzymes by forming a strong covalent bond to an amino acid side-chain group at the enzyme’s active site

A

irreversible enzyme inhibitor

33
Q

It is often regulated by the cell. Often the reason
for this is to conserve energy because if the cell
runs out of chemical energy, it will die; therefore
many mechanism exist to converse energy.

A

Regulation of the Enzyme Activity

34
Q

____________Enzymes that have more than one a single site.

It has an active sites that can be altered by binding of a small molecules-CALLED __________

______________ – inihibit enzyme action
______________- stimulate enzyme action

A

Allosteric Enzymes – Enzymes that have more
than one a single site.

It has an active sites that can be altered by binding of a small molecules called effector molecules or regulators.
Negative allosterism - inihibit enzyme action
Positive Allosterism -stimulate enzyme action

35
Q

The production of the enzyme in an active
form. The proenzyme is converted by proteolysis
to the active from when it has reached the site of
its activity,

A

Proenzyme

36
Q

This is a process in which a chemical group is
covalently added to or removed from the protein.
This covalent modification either activates the
enzyme or turn it off

A

Protein Modification

37
Q
  • Enzymes are often regulated by environmental
    conditions.
  • It is an enzyme regulation process in which
    formation of a product inhibits an earlier
    reaction in the sequence.
A

Feedback Control

38
Q

Assay of enzymes present in _______ or
________ have been routinely carried out in clinical
chemistry laboratories

A

Assay of enzymes present in blood plasma or
serum have been routinely carried out in clinical chemistry laboratories

39
Q
  • is the component that is neither a blood cell
    (serum does not contain white or red blood cells)
    nor a clotting factor; it is the blood plasma with the
    fibrinogens removed. Serum includes all proteins
    not used in blood clotting (coagulation) and all the
    electrolytes, antibodies, antigens and hormones.
A

Serum

40
Q

___________- as disease of different
organs cause elevation of different plasma
enzymes.
___________- Follow up treatment pre
and post measurement of enzymes

A

Diagnosis of diseases - as disease of different
organs cause elevation of different plasma enzymes.
Prognosis of the disease- Follow up treatment pre and post measurement of enzymes

41
Q

Example of Increased permeability

A

hypoxia

42
Q

How it is measure?
- It is measure through _______
- Then blood samples where undergo
________, __________
and __________

A

How it is measure?
- It is measure through blood samples
- Then blood samples where undergo
Electrophoresis, chromatographic techniques
and isoelectric focusing.

43
Q

_________is observed in case to
proteolytic enzymes, glycosidases, and lipases which act on peptide
bonds, glycosidic bonds, and ester bonds.

A

Bond specificity – observed in case to proteolytic enzymes, glycosidases, and lipases which act on peptide bonds, glycosidic bonds, and ester bonds.

44
Q

True or false

The rates of uncatalyzed chemical reactions often triple every time the substrate concentration is tripled.

A

False

The rates of uncatalyzed chemical reactions often double every time the substrate concentration is doubled.

45
Q
  • LOCK-And-KEY MODEL
    An enzyme with a single substrate can be explained using a Lock and Key analogy first postulated in 1894 by Emil Fischer.
    In this analogy, the lock is the ______and the key is the _________
    Only the correctly sized key (substrate) fits into the key hole (active site) of the lock (enzyme)
A
  • LOCK-And-KEY MODEL
    An enzyme with a single substrate can be explained using a Lock and Key analogy first postulated in 1894 by Emil Fischer.

In this analogy, the lock is the enzyme and the key is the substrate
Only the correctly sized key (substrate) fits into the key hole (active site) of the lock (enzyme)

46
Q

_______ is a substance that slows or
stops the normal catalytic function of an enzyme
by binding to it

A

enzyme inhibitor is a substance that slows or
stops the normal catalytic function of an enzyme
by binding to it

47
Q

True or False

When a competitive inhibitor binds to the enzyme active site, inhibitor remains changed (has a reaction occurs)

A

False

When a competitive inhibitor binds to the enzyme active site, inhibitor remains unchanged (no reaction occurs)

48
Q

If inhibitor concentration is greater than substrate concentration , the inhibitor ______

A

If inhibitor concentration is greater than substrate concentration , the inhibitor Dominates

49
Q

_________ act by means of competitive
inhibition.
Example,:
antihistamines are competitive
inhibitors of histidine decarboxylation, the
enzymatic reaction that converts histidine to
histamine which causes allergy and cold symptoms:
watery eyes and runny nose

A

Numerous drugs act by means of competitive
inhibition.
Example:
antihistamines are competitive
inhibitors of histidine decarboxylation, the
enzymatic reaction that converts histidine to
histamine which causes allergy and cold symptoms:
watery eyes and runny nose

50
Q

True or False

Since the binding of noncompetitive enzyme inhibitor is nonspecific, these inhibitors
inactivate a broad range of enzyme

A

True

51
Q

What are the examples of noncompetitive inhibitors :

The binding sites for these ions are __________ located away from the active site. Metal sulfide linkages are formed, an effect that disrupts secondary and tertiary structure.

A

-heavy metal ions lead ion
-silver ion
-mercury ion.

The binding sites for these ions are sulfhydryl (SH groups) located away from the active site. Metal sulfide linkages are formed, an effect that disrupts secondary and tertiary structure.

52
Q

True or False

Inhibition occurs since ESIESI can not form product. It is a dead end complex which has only one fate, to returnto ESES

A

True

53
Q

True or False

Is inhibitors do have structures similar to that of
enzyme’s normal substrate

A

False

inhibitors do not have structures similar to that of enzyme’s normal substrate

54
Q

__________ is sufficiently strong that
addition of excess substrate does not reverse the
inhibition process

A

inhibitor-active site bond is sufficiently strong that addition of excess substrate does not reverse the inhibition process

55
Q

True or false

• The final product in the chain may
inhibit the activity of the second
enzyme. When the concentration of
the final product is low, all of the
reactions proceed rapidly.

A

False

• The final product in the chain may
inhibit the activity of the first
enzyme. When the concentration of
the final product is low, all of the
reactions proceed rapidly.

56
Q

__________ refers to the enzymes that are used directly or as components of the assay system for the determination of number of substances

• Use to detect and quantify certain substances

A

Diagnostic enzymes refers to the enzymes
that are used directly or as components of the
assay system for the determination of number of
substances

• Use to detect and quantify certain substances

57
Q

•Changes in the concentrations of various
biomolecules are indications of :

A

-abnormal metabolic activities
-infections
-infectious
-non-infectious diseases
-inflammatory conditions

58
Q

Example of Obstruction of normal pathways:

A

obstruction of bile duct increases
alkaline phosphatase

59
Q

Example of Increase of the enzyme synthesis:

A

Bilirubin increases the rate of synthesis
of alkaline phosphatase in obstructive liver disease.

BIO CHEM LEC (3 decks)

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