Enzymes Flashcards

1
Q

CK isoenzyme found in highest concentration in the blood

A

CK-MM

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2
Q

Type of inhibition wherein the inhibitor attaches itself to the active site of the enzyme

A

Competitive

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3
Q

Inactive enzymes are termed as ___, which are common among digestive enzymes

A

Proenzymes

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4
Q

Most electronegative LD isoenzyme

A

LD1

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5
Q

What are the conditions for zero-order kinetics?

A

Substrate concentration is higher than enzyme concentration

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6
Q

Which LD isoenzyme appears indicative of arteriosclerotic cardiovascular failure?

A

LD6

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7
Q

This enzyme functions is maintain NADPH in a reduced form which is responsible for regenerating sulfhydryl-containing proteins (ie glutathione) from oxidized to reduced state

A

Glucose-6-phosphate dehydrogenase

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8
Q

The slowest moving fraction of CK is typically elevated in patients with:

A

Skeletal muscle disorders

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9
Q

Hemolyzed serum cannot be used for AST determination because:

A

Erythrocytes contain a large amount of AST

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10
Q

Correct arrangement of the classes of enzymes

A

Oxidoreductase, transferase, hydrolase, lyase, isomerase, ligase

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11
Q

Indicator enzyme used in Karmen method

A

Malate dehydrogenase

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12
Q

Chemical inhibition of ALP using Phenylalanine

A

Inhibits 75% of intestinal and 80% of placental ALP

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13
Q

Which enzyme is most useful in identifying the source of ALP elevation?

A

GGT

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14
Q

An amylase method which measures the disappearance of the starch substrate

A

Amyloclastic

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15
Q

What results when an enzyme is subject to post-translational modifications?

A

Isoform

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16
Q

Also known as organic cofactors

A

Coenzymes

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17
Q

What are the classes of enzymes?

A
Oxidoreductases
Transferases
Hydrolases
Lyases
Isomerases
Ligases
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18
Q

In the Michaelis-Menten curve, Km is defined as the:

A

Substrate concentration at which v is half of Vmax

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19
Q

The Km of an enzyme reaction is ____ proportional to the affinity of a substrate to its enzyme.

A

Inversely

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20
Q

In this type of inhibition, increasing substrate concentration further increases inhibition.

A

Uncompetitive inhibition

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21
Q

1 IU can be defined as:

A

Amount of enzyme that will catalyze the reaction of 1 umol of substrate in 1 minute

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22
Q

1 Katal can be defined as:

A

Amount of enzyme that will catalyze the reaction of 1 mole of substrate in 1 second

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23
Q

1 IU = ___ kat

A

17

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24
Q

These conditions cause a pronounced elevation (>5x) in CK measurement.

A

DMD
Polymyositis
Dermatomyositis
Myocardial infarction

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25
Q

In AMI, CK-MB rises within ____ hours, peaks at ____ hours and return to normal within ____ hours.

A

4-8; 12-24; 48-72

26
Q

The forward reaction of CK determination is also known as:

A

Tanzer-Gilvarg

27
Q

The reverse reaction of CK determination is also known as:

A

Oliver-Rosalki (most commonly preferred)

28
Q

Highest levels of LDH elevation are seen in:

A

Pernicious anemia & hemolytic disorders

29
Q

These conditions cause a pronounced elevation (>5x) in LDH measurement.

A
Megaloblastic anemia
Carcinomatosis
Systemic shock 
Hepatitis
Renal infarction
TTP
30
Q

These conditions cause a slight elevation (3x) in LDH measurement.

A

Liver disease
Nephrotic syndrome
Hypothyroidism
Cholangitis

31
Q

The forward reaction of LDH determination is also known as:

A

Wacker et al

32
Q

The reverse reaction of LDH determination is also known as:

A

Wrobleuski & :a Due

33
Q

In AMI, LDH increases within ____ hours, peaks at ____ hours, and remains elevated for ____ days.

A

12-24; 72; 10

34
Q

LD1 and LD2 are heat-____.

A

Stable

35
Q

____ acts as the coenzyme for both AST & ALT.

A

Pyridoxal phosphate

36
Q

In AMI, AST rises within ___ hours, peaks at ____ hours, and returns to normal in ___ days.

A

6-8; 24; 5

37
Q

These conditions cause a pronounced elevation (>5x) in AST measurement.

A

Acute hepatocellular damage
MI
Circulatory collapse
IM

38
Q

These conditions cause a slight elevation (>3x) in AST measurement.

A
Pericarditis
Cirrhosis
Pulmonary infarction
Delirium tremens
Cerebrovascular accident
39
Q

Method of determination for AST

A

Karmen method

40
Q

Method of determination for ALT

A

Walker et al

41
Q

Highest activity of ALP is seen in:

A

Osteitis deformans (Paget’s disease)

42
Q

These conditions cause a pronounced elevation (>5x) in ALP measurement.

A

Bile duct obstruction
Biliary cirrhosis
Osteogenic carcinoma
Hyperparathyroidism

43
Q

Inhibition with ____ reduces the activity of I & P isoenzymes; inhibition with ____ reduces the activity of B & L isoenzymes.

A

Phenylalanine; levamisole

44
Q

In Bessey-Lowry-Brock & Bowers-McComb ALP determination, ____ is the substrate used.

A

p-nitrophenylphosphate

45
Q

In Shinowara-Jones-Reinhart ALP determination, ____ is the substrate used.

A

B-glycerylphosphate

46
Q

In Babson & Reed ACP determination, ____ is the substrate used.

A

a-naphthylphosphate

47
Q

In Roy ACP determination, ____ is the substrate used.

A

Thymolphthalein monophosphate

48
Q

Most useful application for GGT measurement:

A

Detection of alcoholism & monitoring of alcohol consumption during treatment

49
Q

In acute pancreatitis, AMY levels rises at ____ hours, peaks at ____ hours, remains elevated for ____ hours, and returns to normal within ____ days.

A

2-12; 24-30; 6-72; 3-5

50
Q

These conditions cause a pronounced elevation (>5x) in AMY measurement.

A

Acute pancreatitis
Pancreatic pseudocyst
Morphine adminstration

51
Q

What AMY method is used for stat analysis to rule out acute abdominal pain?

A

Turbidimetry & nephelometry

52
Q

Somogyi unit is defined as the number of mg of glucose in ___ minutes at ___C under specific assay conditions.

A

30; 37

53
Q

____ inhibits salivary amylase.

A

Wheat germ lectin

54
Q

In electrophoresis , ____ amylase is more anodal.

A

Salivary

55
Q

In acute pancreatitis, LIP levels rises at ____ hours, peaks at ____ hours, and remains elevated for ____ days.

A

2-12; 48-72; 10-14

56
Q

In the Modified Cherry-Crandall method, ____ is used as the substrate instead of olive oil.

A

Triolein

57
Q

G6PD deficiency is implicated in ____ anemia.

A

Drug-induced hemolytic

58
Q

This type of cholinesterase hydrolyzes a variety of choline esters and provides a protective function in the body.

A

Pseudocholinesterase

59
Q

In conditions such as ____, ACHE values are decreased.

A

Organophosphate poisoning

60
Q

This is a sensitive, rapid, & the recommended method of ACHE determination.

A

Ellman

61
Q

This is a temperature-sensitive method for ACHE determination, and confers much variability among different labs.

A

Michel