Clinical enzymology Flashcards
(116 cards)
1
Q
Examples of Oxidoreductases
A
LDH, G6PD, GLDH, MDH
2
Q
Examples of Transferases
A
AST, ALT, CK, PK, GGT
3
Q
An enzyme also called SGOT
A
AST (aspartate aminotransferase)
4
Q
SGOT stands for
A
serum glutamic-oxaloacetic transaminase
5
Q
Also known as SGPT
A
ALT (alanine aminotransferase)
6
Q
SGPT stands for
A
Serum glutamic pyruvic transaminase
7
Q
Examples of hydrolases
A
ALP, ACP, Amylase, lipase, chymotrypsin, elastase, cholinesterases, 5’ nucleotidase
8
Q
Ex of Lyases
A
aldolase
9
Q
ex. of Isomerases
A
Triose phosphate isomerase
10
Q
Ex. of Ligases
A
Glutathione synthetase
11
Q
The reaction of Oxidoreductases/Dehydrogenases
A
Oxidation-reduction
12
Q
The reaction catalyzed by Transferases
A
Transfer of functional groups
13
Q
The reaction catalysed by Hydrolases
A
Hydrolysis
14
Q
The reaction catalyzed by Lyases
A
Removal of groups to form double bonds
15
Q
The reaction catalyzed by Isomerases
A
Interconversion of isomers
16
Q
The reaction catalyzed by Ligases
A
Bond formation coupled with ATP hydrolysis
17
Q
describes the rate of catalysis of the enzyme at some particular substrate concentration.
A
Michaelis-Menten equation
18
Q
Double reciprocal of Michaelis-Menten equation
A
Lineweaver-Burk equations
19
Q
What is a first-order kinetics?
A
- Where enzyme concentration exceeds substrate
- More substrate, faster the reaction
- There is continuous increase in velocity as more substrate is added or bound to an enzyme up too a certain point
20
Q
What is zero-order kinetics?
A
- No further increase in velocity but the reaction continues; all active sites have been occupied
21
Q
True or False: Measurement of enzyme is based on its activity and not in concentration.
A
TRUE
22
Q
a method of measurement where reaction is usually stopped by inactivating the enzyme with weak acid
A
Fixed-time/endpoint
23
Q
A method of measurement where multiple measurements of absorbance change as a function of time.
A
Continuous-monitoring/Kinetic
24
Q
A unit of measure for the amount of enzyme that catalyzes the reaction of 1 umol of substrate per minute
A
IU (international unit)
25
a unit of measurement for the amount of enzyme that catalyzes the reaction of 1 mol of substrate per second.
Katal
26
how many Katal are there in 1 IU
17 nanokatal or 0.0167 microkatal
27
In which pH range do most reactions occur
pH 7-8, except ACP and ALP
28
The denaturation point of enzymatic reactions is...
40-50 degree Celsius
29
A factor that affect enzymatic reactions that must bind to particular enzymes before a reaction occurs
Cofactors
30
Are inorganic cofactors
Activators
31
Are organic cofactors
Coenzymes
32
What are the three types of enzyme inhibitors?
competitive, non-competitive, uncompetitive
33
Inhibitor that binds to the active site
Competitive inhibitor
34
An inhibitor that binds to site other than the active site (allosteric site)
Non-competitive inhibitor
35
An inhibitor that binds to the enzyme-substrate complex
Uncompetitive inhiitor
36
High-molecular mass forms of the serum enzymes that can be bound to Immunoglobulin and non-immunoglobulin
Macroenzymes
37
Which tissues is CK found?
brain, heart, skeletal muscles
38
Enumerate the CK Typical Isoenzymes
CK-BB (CK 1), CK-MB (CK 2), CK-MM (CK 3)
39
enumerate CK Atypical Isoenzymes
MI, Macro-CK
40
CK Isoenzyme that is elevated in CNS damage, tumors, presence of macro-CK
CK-BB
41
A CK isoenzyme present in significant amounts in cardiac tissue
CK-MB
42
A CK isoenzyme present in striated muscle and normal serum
CK-MM
43
The only CK isoenzyme that is a cathode
MI (Mitochondrial CK)
44
What are the methods for CK determination called?
Tanzer-Gilvarg and Oliver-rosalki
45
Which CK method is a forward reaction?
Tanzer-Gilvarg
46
Which CK method is a reverse reaction?
Oliver-Rosalki
47
Rf values for Total CK
Male: 15-160 U/L (37oC)
Female: 15-130 U/L (37oC)
48
Which sample is used in CK determination?
Heparinized plasma or serum
49
True or False: Hemolysis falsely decreases CK result
False
50
Tissue sources of Lactate Dehydrogenase
Heart, RBCs, renal cortex, lungs, liver, skeletal muscle
51
LD isoenzyme most abundant in the heart
LD-1 and LD-2
52
LD isotype predominant in the lungs
LD-3
53
LD isotype predominant in the liver and skeletal muscles
LD-4 and LD-5
54
The most labile among LD isotypes
LD-5
55
At what temperature is LD required to be stored?
25oC
56
Forward reaction for LD determination is called...
Wacker method
57
Reverse reaction for LD determination is called...
Wroblewski-Ladue method
58
Rf value for LD
100-225 U/L (37oC)
59
The three enzymatic myocardial infarction markers
CK, AST, LD
60
True or False: CK peaks at 48-72 hours in cases of MI
False
61
True or False: AST normalizes in 4-5 days in MI
True
62
True or False: LD starts to increase at 12-24 hours in MI
True
63
In MI, LD value normalizes in___.
10 days
64
Tissue sources of AST/SGOT
liver, heart, skeletal muscles
65
Tissue sources of ALT/SGPT
liver
66
Diagnostic significance of ALT
Acute hepatocellular disorders
67
Diagnostic significance of AST in >5x/pronounced elevation
acute hepatocellular disorders
circulatory collapse
myocardial infarction
68
Diagnostic significance of AST in 3-5x/moderate elevation
```
Muscular dystrophy
Hepatic tumor
biliary obstruction
Congestive Heart Failure
Cardiac arrhythmia
```
69
diagnostic significance of AST in <3x/ slight elevation
Cirrhosis, pericarditis, pulmonary infarction, cerebrovascular accident
70
An isoenzyme elevated in extensive necrotic damage especially in alcoholic hepatitis or fulminant hepatic failure
Mitochondrial AST
71
True or False: AST has a higher half-life than ALT
False
72
An AST isoenzyme that is routinely determined in the laboratory
Cytoplasmic AST
73
What type of method is Reitman-Frankel?
Colorimetric-Spectrophotometric assay
74
Reagents used in Reitman-Frankel
2,4-dinitrophenylhydrazine (color developer)
| 0.4 N NaOH (color intensifier)
75
Reitman-Frankel resulting color
brown, blue
76
AST determination method based on the Karmen method
Coupled Enzymatic Reaction
77
RF value for AST and ALT
AST: 5-35 U/L
ALT: 7-45 U/L
78
Tissue sources of ALP
liver, bone, placenta, intestine
79
Diagnostic significance of ALP in pronounced elevation
```
bile duct obstruction
biliary cirrhosis
Paget's disease (highest elevation)
Osteogenic sarcoma
Hyperparathyroidism
```
80
Diagnostic significance of ALP in moderate elevation
```
Granulomatous or infiltrative disease
Infectious mononucleosis
Metastatic bone tumors
Rickets
Osteomalacia
```
81
Diagnostic significance of ALP in slight elevation
```
Viral hepatitis
Cirrhosis
Healing bone fractures
Growing children
Pregnancy due to placental isoenzyme
```
82
Isoenzyme whose presence in serum depends in the blood group and secretor status of the individual; bound by A erythrocytes; level increases after consumption of fatty meal
Intestinal ALP
83
True of False: Increase in pH falsely decrease ALP activity
False (As Co2 escapes, pH increases which may falsely increase ALP)
84
Reference for ALP determination
Bowers-McComb
85
What does the Bowers-McComb test utilize
PNPP (para-nitrophenyl phosphate)
86
Color result in Bowers-McComb
Yellow
87
Rf value for ALP
30-90 U/L
88
Tissue sources for amylase
pancreas, salivary glands
89
Tissue source/s for lipase
pancreas
90
Diagnostic significance for Amylase
Acute pancreatitis, mumps, parotitis, macroamylasemia
91
Diagnostic significance for Lipase
Acute pancreatitis
92
Isoenzymes for Amylase
Pancreatic AMS
| Salivary AMS
93
Isoenzymes for lipase
None
94
Most specific enzyme in pancreatitis
Lipase
95
Bonus
In Amylase determination, lipemic samples must be avoided
| Pain relievers should not be consumed, this may cause falsely increased results
96
[Amylase determination] Decrease in color of starch-iodine complex
Amyloclastic method
97
[Amylase determination] Classic reference method reported in Somogyi units
Saccharogenic method
98
[Amylase determination] Increase in color intensity of soluble dye-substrate solution
Chromogenic method
99
[Amylase determination] Commonly used, increase in absorbance of NADH at 340 nm
Coupled-Enzymatic/Continuous-monitoring method
100
Rf values for Amylase
Serum: 25-130 U/L
Urine: 1-15 U/hour
101
[Lipase determination] A method that uses olive oil as a substrate
Cherry-Crandall method
102
[Lipase determination] Measures rate of clearing as fats are hydrolyzed by LPS
Turbidimetric method
103
[Lipase determination] Based on coupled reactions with peroxidase or glycerol kinase
Colorimetric method
104
Rf value for Lipase
0-1.0 U/mL (<38 units/L)
105
Used to identify the source of elevated ALP in hepatobiliary disorders, alcoholic liver disease, microsomal induction by drugs and alcohol
GGT
106
Used to identify the source of ALP in Intrahepatic cholestasis
5' NT
107
Sources include prostate (richest) and RBCs
Resolution of rape cases
screen prostatic carcinoma; replaced by PSA
Traditional determination; Roy Method
ACP
108
Drug-induced hemolytic anemia;
Exacerbated by food that contain oxidative
metabolites, producing oxidative stress to
RBCs
Clinically significant if deficient in RBCs
G6PD
109
```
Normally high in plasma
Pesticide poisoning reduces PChE
Organophosphate and carbamate poisoning
Liver disease due to decrease synthesis
Genetic variants resulting in abnormal
response to muscle relaxants
Clinically significant if deficient in serum
```
PChE (Pseudocholinesterase enzyme)
110
Increased in skeletal muscle disorders
Aldolase
111
Blood pressure regulation
ACE
112
Hemolytic anemia
PK
113
Acute pancreatitis: increased
Chronic pancreatic insufficiency: decreased
Clinically significant if deficient in serum
Trypsin
114
Associated with pancreatic insufficiency
Correlated w/ fecal fats & muscle fiber in
stool
Clinically significant if deficient in serum
Chymotrypsin/Elastase 1
115
Acute myocardial infarction
| But not used as a marker for AMI
Glycogen phosphorylase
116
Bonus
↑ ALP, ↑ GGT, ↑ 5’ NT: hepatobiliary disorder
| ↑ ALP, N GGT, N 5’ NT: bone disorder
