Clin Chem Exam 2 Clin Enzymology And Enzyme Kinetics

Front 1

organic molecules that accelerate biochemical reactions

Back 1

Enzymes

Front 2

Enzymes act as a ____, and emerge from the reaction _____, and in the same form and concentration as they were when entering the reaction.

Back 2

catalyst; unchanged

Front 3

What does lactate dehydrogenase do?

Back 3

Conducts a dehydrogenase (oxidation) reaction on lactate

Front 4

What does AST do?

Back 4

conducts a transamination on aspartate, most transaminases require pyridoxal phosphate

Front 5

What does glucose oxidase do?

Back 5

conducts an oxidation reacton on glucose, most oxidases use O2

Front 6

Creatine Kinase (CK) does?

Back 6

conducts a kinase(phosphorylation) reaction on creatine, most kinases use ATP

Front 7

Transferases involve the transfer of any substrate group other than_____

Back 7

Hydrogen

Front 8

Alkaline Phosphatase does?

Back 8

conducts a phosphotase reaction at alkaline pH

Front 9

Amylase does?

Back 9

conducts hydrolysis reaction on amylose (starch)

Front 10

What is the sequence of an enzymatic reaction?

Back 10

1. enzyme binds to substrate (E+S <--> ES complex)
2.bonds are rearranged forming product (ES-->EP)
3. product is released from enzyme (EP--> E+P)

Front 11

formula for equilibrium constant is...

Back 11

ratio of products/ ratio of reactants

Front 12

In the Michaelis- Menten Model, the substrate

Back 12

readily binds to enzyme at low substrate concentration

Front 13

In the Michaelis- Menten Model, first order kinetics is..

Back 13

When the rate of reaction increases as more substrate is added. Rate is directly proportional to substrate concentration

Front 14

In the Michaelis- Menten Model, Zero order kinetics is...

Back 14

when the subrate concentration is high enough to saturate all enzyme and reaction velocity is at its maximum. Once product is formed, free enzyme reacts with free substrate. Rate only depends on enzyme concentration.

Front 15

What is the Michaelis- Menten equation

Back 15

V= Vmax[S]/ Km+[S]

Front 16

What is the Lineweaver-Burk equation

Back 16

1/V = Km/Vmax[S]+1/Vmax

Front 17

What are three factors influencing rate of reaction?

Back 17

Temperature, pH, Ionic strength

Front 18

How does temperature influence rate of reaction?

Back 18

Higher temp speeds up the reaction b/c of higher intermollecular movement and intermollecular collisions; for every 10 degree increase reaction rate doubled. Too high of temp= denaturation

Front 19

How does pH influence rate of reaction?

Back 19

Most enzyme reactions occure b/w 7.0-8.0 ; [H+] -> change in ionizable groups on the enzyme-> change in shape of proteins-> lowers rate of reaction

Front 20

How does Ionic strength influence rate of reaction?

Back 20

Ionic strength changes polarity of the medium which changes the shape of the enzyme which lowers the rate of reaction. Body enzymes are optimized for isotonic conditions.

Front 21

Absorbance readings are measured continuously during the incubation

Back 21

kinetic assays

Front 22

measures absorbance once after a known incubation period, and then calculates delta abs/min

Back 22

One point assay or end point assay

Front 23

In a one-point assay _____ cannot be measured

Back 23

first order reaction

Front 24

Advantages of kinetic assay (2)

Back 24

1. you can inspect the data and use only the zero order reaction
2. can detect and eliminate lag phase or substrate exhaustion

Front 25

Advantage of a one- point assay

Back 25

you can run a big batch of samples all at once

Front 26

Highest activity in skeletal muscle, cardiac muscle, and brain tissue but also present in intestinal tract, kidney, uterus, thyroid, liver and prostate

Back 26

CK- creatine kinase

Front 27

CK-1 (BB) is found in...

Back 27

brain and intestine

Front 28

CK-2 (MB) is found...

Back 28

mostly cardiac muscle (and some skeletal)

Front 29

Ck-3 (MM) is found in...

Back 29

skeletal and cardiac muscle

Front 30

Total CK levels are always increased in _____(MB) and ______ (MM) (50 to 100xULN)

Back 30

AMI (acute myocardial infarction) ; Muscular dystrophy

Front 31

Reference range for CK

Back 31

25-170 U/L (180-190 can usually be disregarded also)

Front 32

Why is the range for CK so broad?

Back 32

Creatine Kinase is a very non-specific enzyme

Front 33

When are sources of error seen in CK measurements?

Back 33

Hemolyzed sample because AK is released, and in patients who excercise becasue of increased muscle activity

Front 34

Found in muscle(cardiac and skeletal), liver, kidney, erythrocytes, luekocytes, lungs, lymph nodes, spleen, and brain

Back 34

Lactact dehydrogenase (LD)

Front 35

The isoenzymes in LD are? Which is more specific to heart?

Back 35

LD1 (HHHH) to LD5 (MMMM); LDH1 is more specific to heart. (the more 'H' the more heart)

Front 36

Which isoenzyme in LD migrates fastest toward the anode? Which migrates slowest?

Back 36

LD1 migraes fastest to the anode; LD5 migrates slowest

Front 37

If LD2>LD1 ...

Back 37

patient is healthy

Front 38

if LD1>LD2...

Back 38

AMI

Front 39

What three things is LD elevated in?

Back 39

Liver disease, Hemolysis of RBC, and myocardial disorders

Front 40

What are sources of error in Analytical measurement of LD?

Back 40

Hemolysis (100-150x more in RBCs), refrigerated temperature (should be stored at R.T.)

Front 41

What is the optimal temperature for LD to be stored at? Why should LD not be refrigerated?

Back 41

25 C. LD activity is lost quickly when refrigerated.

Front 42

Found in highest concentration in liver, cardiac, and skeletal muscle (small amounts in kidney, pancreas and RBCs)

Back 42

Aspartate Aminotransferase (AST)

Front 43

AST is a good marker for...

Back 43

Intra hepatic chirrosis

Front 44

Increased AST levels are seen in?

Back 44

MI (levels peak in 24 hours)

Front 45

Increase in pulmonary embolism is characteristic of...

Back 45

AST

Front 46

When levels of AST are 100x ULN, it is characteristic of...

Back 46

viral hepatitis

Front 47

What things are commonly seen in increased AST levels?

Back 47

MI, Pulmonary embolisms, acute hepatocellular disorders (viral hepatitis, chirrosis), skeletal muscle disorders(muscular dystrophy &inflammatory conditions)

Front 48

Reference range for AST

Back 48

15-30 U/L

Front 49

What type of sample must be used in analytical measurement of AST

Back 49

Non-hemolyzed

Front 50

Predominantly specific to liver, levels remain normal in AMI, Increased levels seen in hepatocellular disorders

Back 50

Alanine Aminotransferase

Front 51

pre hepatic cellular disorders are more specific to______, while post hepatic are more specific to ______.

Back 51

ALP; GGT

Front 52

In acute inflammatory conditions of the liver, ____>_____ and remains elevated for a longer period of time due to the longer half life of _____.

Back 52

ALT;AST:ALT

Front 53

Reference range for ALT

Back 53

6-37 U/L

Front 54

In analytical measurement of ALT, we measure what?

Back 54

The decrease in absorbance of NADH @ 340 nm

Front 55

Most significant enzyme in hepatobiliary and bone disorders

Back 55

Alkaline Phosphatase (ALP)

Front 56

Major isoenzymes of ALP are found where? (3)

Back 56

Bone, Liver, Placenta and Intestine

Front 57

What three ways can the major isoenzymes of ALP be distinguished?

Back 57

Heat stability, electrophoresis, and chemical inhibition

Front 58

How are ALP isoenzymes distinguished in heat stability?

Back 58

bone burns (<20%), liver lingers (~25-55%), and intestine and placenta persists (>75%) *note: problems are seen with this method*

Front 59

When ALP isoenzymes are seperated by electrophoresis, what is seen?

Back 59

Liver is fastest, followed by bone, placental and intestine

Front 60

When ALP isoenzymes are seperated by chemical inhibition, what is used and what is seen?

Back 60

Phenylalanine; phenylalanine inhibits intestinal and placental ALP more than bone and liver

Front 61

What (tumor) isoenzyme resembles placental ALP?

Back 61

Regan (tumor) or isoenzyme marker

Front 62

In the liver, ALP lines the ______ and the________

Back 62

sinusoids; bile canaliculi

Front 63

In bone, ALP is seen in ______

Back 63

osteoblast( involved in the production of bone matrix)

Front 64

In _______ ALP is 3 to 10x ULN

Back 64

Bilary tract obstruction

Front 65

In hepatocellular disorders ALP is...

Back 65

<3x ULN

Front 66

ALP is increased in bone disorders such as? (4)

Back 66

osteomalacia, paget's disease, rickets, osteogenic sarcoma

Front 67

In adults older that 50, ___
is increased in healing bone fractures

Back 67

ALP

Front 68

ALP can be increased in diseases of digestive tract due to

Back 68

intestinal fraction

Front 69

In analytical measurements of ALP sources of error include?? (2)

Back 69

high fat meals (intestinal ALP), Left at R.T. or refirigerated (run ASAP)

Front 70

Reference ranges for ALP are

Back 70

30-90 U/L

Front 71

Found mostly in prostate, used to monitor therapy, measured by the p-nitrophenol reaction, also found in platelets

Back 71

ACP acid phosphatase

Front 72

ACP plays a major significance in detection of

Back 72

prostatic carcinoma (metastasized carcinoma)

*Also increased in benign prostatic hyperplasia and prostatic surgery*

Front 73

Sources of error in measuring ACP include:

Back 73

hemolysis, room temperature (loss of CO2-->pH change)

Front 74

Cinical applications in liver and bilary system disorders, Alcohol induces synthesis of this enzyme

Back 74

GGT (gamma- glutamyl transferase)

Front 75

GGT increases in what 3 things?

Back 75

pancreatitis, diabetes, and MI

Front 76

reference range for GGT

Back 76

up to 45 U/L

Front 77

GGT is the most sensitive indicator of liver damage from what?

Back 77

ethanol intake

Front 78

catalyzed the breakdown of starch and glycogen; tissue sources include pancreas and salivary glands

Back 78

Amylase

Front 79

Elevated amalyse is diagnostic of

Back 79

acute pancreatitis

Front 80

Sources of error with amylase include

Back 80

high triglycerides (supresses/inhibits amylase), EDTA or citrate anticoagulant

Front 81

reference range for amylase

Back 81

35-125 U/L

Front 82

Hydrolyzes ester linkagesof fats to produce alcohols and fatty acids; presesnt in pancreas,stomach, luekocytes and adipose tissue

Back 82

Lipase

Front 83

Specific for diagnosis of acute pancreatitis

Back 83

Lipase

Front 84

Hydrolyzed esters of choline to destroy poisons or drugs; found in liver, heart, and white matter of brain

Back 84

Cholinesterase

Front 85

What are the two types of cholinesterase? Which one do you measure?

Back 85

acetylcholinesterase and psuedocholinesterase; we measure psuedocholinesterase

Front 86

Not specific but a sensitive marker for organophosphate poisoning

Back 86

Cholinesterase

Front 87

Decrease in Cholinesterase is seen in what 4 things?

Back 87

liver disease, starvation, burns and insecticide poisoning

Front 88

Sources of error in Cholinesterase measurements are

Back 88

hemolysis (erythrocytes contain acetylcholinesterase)

Front 89

Hydrolyzed esters of choline to destroy poisons or drugs; found in liver, heart, and white matter of brain

Back 89

Cholinesterase

Front 90

What are the two types of cholinesterase? Which one do you measure?

Back 90

acetylcholinesterase and psuedocholinesterase; we measure psuedocholinesterase

Front 91

Not specific but a sensitive marker for organophosphate poisoning

Back 91

Cholinesterase

Front 92

Decrease in Cholinesterase is seen in what 4 things?

Back 92

liver disease, starvation, burns and insecticide poisoning

Front 93

Sources of error in Cholinesterase measurements are

Back 93

hemolysis (erythrocytes contain acetylcholinesterase)