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Clinical Chemistry > Enzymes: Amylase/Lipase > Flashcards

Enzymes: Amylase/Lipase Flashcards

0
Q

What reaction does alpha amylase catalyze?

A

Catalyzes the hydrolysis of alpha-1,4-glycosidic bonds in polymers of glucose

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1
Q

What are the 2 types of amylase?

A

Beta and alpha

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2
Q

What is the cofactor required for amylase catalytic activity?

A

Calcium

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3
Q

What is the pH optimum for amylase catalytic activity?

A

6.9-7.0

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4
Q

Is it normal to find amylase in the urine?

A

Yes, amylase is small enough to be filtered by the glomerulus of the kidney

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5
Q

What are activators for amylase activity?

A

Univalent anions, such as Chloride or Bromide

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6
Q

Amylase is inhibited by all anticoagulants except:

A

Heparin

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7
Q

How long is amylase stable at room temperature?

A

1 week

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8
Q

How long is amylase stable at refrigerated temperature?

A

2 months

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9
Q

What is endoamylase?

A

Hydrolysis occurs at random locations in the polysaccharide

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10
Q

What sort of amylase is endoamylase?

A

Alpha amylase

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11
Q

What is exoamylase?

A

Enzyme found in plants and bacteria only. It acts only on the bonds at the terminal end of a glucose chain.

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12
Q

What type of amylase is exoamylase?

A

Beta amylase

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13
Q

If a specimen needs to be diluted for amylase measurement, what do you need to use to dilute it?

A

Saline

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14
Q

In amylase measurement, why does saline need to be used instead of water?

A

If water is used, chloride will be diluted considerably. Chloride is needed to activate the reaction catalyzed by amylase.

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15
Q

Where is amylase found?

A

Found in many tissues throughout the body

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16
Q

Where are the highest amylase concentrations found?

A

Pancreas and salivary glands

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17
Q

How many salivary isoenzymes are there?

A

3 - S1, S2, S3

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18
Q

How many pancreatic isoenzymes are there?

A

3 - P1, P2, P3

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19
Q

Amylase is stable until what temperature is reached?

A

50 degrees Celsius

20
Q

How is the pain associated with acute pancreatitis caused?

A

Proteolytic enzymes are released throughout the pancreas, causing tissue destruction and leading to the epigastric pain. This is called autolysis.

21
Q

Why does amylase increase so drastically in acute pancreatitis?

A

The autolysis associated with the proteolytic enzymes causes a release of pancreatic amylase into the serum.

22
Q

When does serum amylase increase in acute pancreatitis?

A

5-8 hours after disease onset

23
Q

When do serum amylase levels peak in acute pancreatitis?

A

They peak with 24 hours of disease onset

24
Q

When do serum amylase levels return to normal after an attack of acute pancreatitis?

A

Return to normal range in 3-5 days

25
Q

When do urine amylase levels return to normal after an attack of acute pancreatitis?

A

Will remain elevated for up to 10 days

26
Q

What disease states is acute pancreatitis associated with?

A

Alcoholism, hyperlipemia, uremia, hyperparathyroidism, trauma

27
Q

Is the serum amylase level specific for pancreatitis?

A

Serum amylase levels can be elevated in a wide variety of disease states

28
Q

What is macroamylasemia?

A

Amylase will complex with immunoglobulins, forming a large complex that can not be cleared from the serum by the kidneys

29
Q

What immunoglobulins will amylase complex with when macroamylasemia is present?

A

IgG or IgA

30
Q

In macroamylasemia, will serum amylase be increased, decreased, or normal?

A

Increased

31
Q

In macroamylasemia, will urinary amylase be increased, decreased, or normal?

A

Normal or decreased

32
Q

How can macroamylasemia and acute pancreatitis be differentiated?

A

Calculate the amylase clearance/creatinine clearance ratio

33
Q

What is the formula for the amylase clearance/creatinine clearance ratio?

A

(Urine amylase x serum creatinine)/(serum amylase/urine creatinine) x 100%

34
Q

What is the normal ACCR?

A

2-5%

35
Q

If the ACCR is less than 2%, what does this indicate?

A

Macroamylasemia

36
Q

If the ACCR is increased, what does this indicate?

A

Acute pancreatitis

37
Q

What is the modified saccharogenic method?

A

A polysaccharide is hydrolyzed by amylase to form reducing sugars. The increasing levels of reducing sugars are measured using the hexokinase method.

38
Q

What must be corrected for in the modified saccharogenic method?

A

Endogenous glucose, which will falsely increase the results

39
Q

How do you correct for endogenous glucose in the modified saccharogenic method?

A

Use a serum blank and subtract glucose from the blank from the result. Or you can allow 10 minutes preincubation to allow glucose in the sample to react.

40
Q

What type of amylase normally dominates in the serum?

A

S type

41
Q

What type of amylase dominates normally in the urine?

A

P type

42
Q

How would you further differentiate amylase isoenzymes?

A

Use isoenzyme fractionation

43
Q

What methods can be used for amylase isoenzyme fractionation?

A

Electrophoresis, isoelectric focusing, chemical inhibition, inhibition of salivary amylase with monoclonal antibodies

44
Q

During isoenzyme fractionation, amylase enzymes of which origin will migrate the fastest?

A

Salivary origin

45
Q

What are the most commonly observed amylase isoenzyme fractions?

A

P2, S1, S2

46
Q

In acute pancreatitis, what amylase isoenzyme is predominant?

A

P3

47
Q

What reaction does lipase catalyze?

A

Lipase catalyzes the hydrolysis of dietary triglycerides with long chain fatty acids.

48
Q

What is required by lipase for optimal activity?

A

Colipase, protein secreted by the pancreas

Clinical Chemistry (6 decks)

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