Serum Enzymes

Question 1

What is the reference range for ALP

Answer 1

30-130 U/L

Question 2

What is the reference range for LD

Answer 2

100-225 U/L

Question 3

What is the reference range for ALT

Answer 3

Female <40 U/L
Male < 60 U/L

Question 4

What is the reference range for AST

Answer 4

Female <35 U/L
Male <45 U/L

Question 5

What is the reference range for CK

Answer 5

Female <200
Male <250

Question 6

What is the reference range for GGT

Answer 6

<80 U/L

Question 7

What is the reference range for AMY

Answer 7

30-150 U/L

Question 8

What is the reference range of LIP

Answer 8

0-60 U/L

Question 9

What is activation energy

Answer 9

the amount of energy needed to raise all the molecules in 1 mol of a a compound at a certain temperature to the transitional state at the peak of the energy barrier, this corresponds to the formation of an activated enzyme-substrate complex

Question 10

What is an isoenzyme

Answer 10

a group of enzymes that catalyze the same reaction but are encoded by different genes, each isoenzyme has a different molecular structure and varying physical, immunological and biochemical properties

Question 11

What is a cofactor

Answer 11

non-protein molecules needed for enzyme activity

Question 12

What is an activator

Answer 12

inorganic cofactor that when bound to an enzyme icreases the enzymes activity

Question 13

What is a coenzyme

Answer 13

organic, low molecular weight substances which combines with an inactive protein

Question 14

What is an apoenzyme

Answer 14

an inactive form of an enzyme that requires a coenzyme to be converted into an active holoenzyme

Question 15

What is a prostetic group

Answer 15

a coenzyme bound to an apoenzyme

Question 16

What is a holoenzyme

Answer 16

the active form of an apoenzyme formed by the combination of the apoenzyme with its coenzyme

Question 17

What is denaturation

Answer 17

a change in the structure of a protein accompanied by a loss of activity

Question 18

What are causes of denaturation

Answer 18

extreme pH, elevated temperature, changes in ionic strength and chemical modifiers

Question 19

What are enzymes

Answer 19

proteins that function as catalysts by lowering the activation energy

Question 20

What is the optimum pH for most physiological enzymes

Answer 20

7.0-8.0

Question 21

What do buffers do

Answer 21

control the pH of enzyme reactions

Question 22

What is the optimal temperature for physiological enzymes

Answer 22

37C

Question 23

What does a 10C increase in temperature do to the reaction rate

Answer 23

doubles it

Question 24

What is the rate of reaction dependant on in zero order kinetics

Answer 24

enzymes

Question 25

What is the rate of reaction dependant on in first order kinetics

Answer 25

substrate

Question 26

What is competitive inhibition

Answer 26

the inhibitor is a structural analog of the substrate and competes for the active site

Question 27

How do you overcome competitive inhibiton

Answer 27

adding more substrate

Question 28

What type of inhibition is competitive inhibition

Answer 28

reversible

Question 29

What is non-competitive inhibition

Answer 29

an inhibitor binds tot he enzyme at an allosteric site causing conformational changes in the enzyme structure

Question 30

What is uncompetitive inhibition

Answer 30

the inhibitor binds to the enzyme-substrate complex preventing the creation of products

Question 31

How are enzymes measured

Answer 31

the concentration of an enzyme is directly proportional to the measurable catalytic activity of the enzyme

Question 32

What are fix time methods

Answer 32

the reaction is started, incubated for a specified time at a set temperature and then the reaction is stopped and the change in absorbance is measured

Question 33

What are continuous monitoring methods

Answer 33

the reaction is started and incubated at a set temperature for a set time, the change in absorbance is measured at multiple time points or continuously until the reaction is stopped

Question 34

Where is ALP found

Answer 34

intestine, liver, bone and placenta as well as the surface of RBCs

Question 35

What is the significance of ALP

Answer 35

clinically significant sources are osteoblasts and hepatocytes, increased in bone diseases and liver issues as well as in dialysis patients and cancer

Question 36

What are the activators of ALP

Answer 36

zinc and magnesium

Question 37

What are the inhibitors of ALP

Answer 37

phosphate and anticoagulants

Question 38

What are the limitations of ALP testing

Answer 38

measurement should occur within 4 hours, ALP increases at 4C and RT, hemolysis is an interference

Question 39

What is the tissue distribution of LD

Answer 39

throughout the body though concentrated into the heart, liver, skeletal muscles, RBC, platelets and lymph nodes

Question 40

What is the clinical significance of LD

Answer 40

increased in hemolytic and megaloblastic anemia as well as in liver disease and myocardial infarction

Question 41

What is the coenzyme of LD

Answer 41

NAD

Question 42

What are the limitations of LD testing

Answer 42

a serum sample is prefered and samples should be stored at RT, hemolysis is an interference

Question 43

What is the tissue distribution of ALT

Answer 43

liver and kidneys

Question 44

What is the clinical significance of ALT

Answer 44

increased in hepatic diseases

Question 45

What is the coenzyme of ALT

Answer 45

vitamin B6

Question 46

What are the limitations of ALT testing

Answer 46

should be measured on the same day as collection, only stable at -70C, hemolysis is an interference

Question 47

What is the tissue distribution of GGT

Answer 47

kidney, bile ducts of liver, pancreas and liver

Question 48

What is the clinical significance of GGT

Answer 48

indicator of hepatobiliary disease, elevated in alcohol related issues

Question 49

What is the activator for GGT

Answer 49

magnesium

Question 50

What are the inhibitors of GGT

Answer 50

citrate, oxalate, fluoride

Question 51

What are the limitations of GGT testing

Answer 51

serum and plasma are stable at 4C, ethanol warfarin phenobarbital and phenytoin can cause a false increase

Question 52

What is the tissue distribution of CK

Answer 52

skeletal muscle, heart, brain

Question 53

What is the clinical significance of CK

Answer 53

skeletal muscle diseases and heart disease

Question 54

What is the activator of CK

Answer 54

magnesium

Question 55

What is the coenzyme of CK

Answer 55

ATP

Question 56

What are inhibitors of CK

Answer 56

All coagulants except heparin, Maganese, calcium, zinc, copper and excess magnesium

Question 57

What are limitations of CK testing

Answer 57

samples are stable for upto 48 Hr at 4C, hemolysis will intefere

Question 58

What is the tissue distribution of amylase

Answer 58

salivary glands, pancreas, ovaries, fallopian tubes and lungs

Question 59

What is the clinical significance of amylase

Answer 59

increased in salivary gland inflammation, acute pancreatitis and other intra-abdomin disorders

Question 60

What is the activator for amylase

Answer 60

calcium

Question 61

What are the inhibitors for amylase

Answer 61

all anticoagulants except heparin

Question 62

What are the limitations of amylase testing

Answer 62

stable at RT, morphine and opiates elevate

Question 63

What is the tissue distribution of lipase

Answer 63

pancreas, stomach and small intestine

Question 64

What is the clinical significance of lipase

Answer 64

elevated in acute pancreatitis, gastic or duodenal ulcers and intestinal obstruction

Question 65

What is are the cofactors of lipase

Answer 65

colipase and bile salts

Question 66

What are the limitations of lipase testing

Answer 66

stable at RT for 1 week, hemolysis is an inhibitor