Enzymology Flashcards
injected enzymes
streptokinase, urokinase
viral diseases (herpes, AIDS) treated by
azidothymidine
treatment of acute lymphoblastic leukemia
glutaminase
functional plasma enzymes
lipoprotein lipase, pseudocholinesterase
sources of non-functional plasma enzymes
- cell damage (MI, viral hepatitis)
- Obstruction of normal pathways (obstruction of bile duct)
- increase of enzyme synthesis (bilirubin increases rate of ALP synthesis in obstructive liver disease)
- increased permeability of cell membrane as in hypoxia
causes of increase serum level of enzymes
- increased cell turnover
- cellular proliferation (neoplasia)
- increased enzyme synthesis (enzyme induction )
- obstruction to secretion
- decreased clearance
AST is also called
glutamate-oxaloacetate transaminase
AST is significantly elevated in
MI
AST is moderately elevated in
liver diseases
ALT is also called
glutamate-pyruvate transaminase
ALT normal serum level
5-30 U/L
moderate increase of ALT
chronic liver disease (cirrhosis and malignancy)
AST normal serum level
8-40 U/L
very high values of ALT in
acute hepatitis
AST is higher than ALT in
Acute Alcoholic hepatitis
ALP present in
Liver, bone, intestines, kidneys and white blood cells
ALP normal serum level
40-125 U/L
ALP increases in
Cholestatic liver disease
Placental ALP elevates in
Malignancies ( ovarian, lung, gastrointestinal cancers, hodgkin’s disease )
Gamma-glutamyltransferase present in
Liver, also in intestines, kidneys, pancreas and prostate
GGT normal serum level
6-45 U/L
Nucleotide phosphatase also called
5’nucleotidase
NTP is a marker enzyme for
Plasma membrane
Normal NTP level
2-10U/L
NTP moderately increased in
Hepatitis
NTP is highly elevated in
Biliary obstruction
Silent MI occur in
Patients with DM
Biomarker released from damaged tissue within 1 hr
Myoglobin
Biomarker with high sensitivity but low specificity
Myoglobin
Time for myoglobin to rise is
1-4 hrs, peak time 6-12 hrs, return to normal in 24hrs
Why myoglobin has not been used by most hospitals
Due to its poor clinical specifity
Contractile protein not enzyme
Troponin
Found in cardiac and skeletal muscle, elevated during kidney and skeletal muscle damage
Troponin T
Troponin T early rise after
3-4hrs
Peak is 24hrs
Found only in cardiac muscle
Troponin I
More specific
Troponin I
Troponin I rises
4-6hrs
Peak is at 18hrs
Returns to normal level in 14days
Can’t be used to detect re-infarction
Troponin I
Can detect smaller infarction than other biomarkers can do (very sensitive)
Troponin
Enzyme catalyses the conversion of creatine to phosphocreatine
Creatine kinase
High specificity for cardiac tissue ( rise 4-6hrs)
CK
Peaks at about 12 hrs returns to baseline at 24-48 hrs
CK
Normal level of CK
15-100U/L for males
10-80 U/L for females
………. catalyzes the conversion of pyruvate to lactate
Lactate dehydrogenase
normal level of LDH
55-140IU/L
if LDH1 is greater than LDH2, then the person is
positive for MI
LDH levels are high in
tissue breakdown hemolysis cancer meningitis encephalitis HIV
An enzyme that has only limited diagnostic value because of its nonspecific nature
LDH
its elevation (8-12)hrs after infarction peak levels (24-48)hrs after MI
AST
enzyme not indicative of MI, can cause a rise in the levels (as in trauma to the skeletal muscle, liver disease)
AST
catalyses the hydrolysis of starch into maltose
amylase
first enzyme to be discovered
amylase
normal level of amylase
140U/L
amylase is made in
pancreas and salivary gland
clinical significances of amylase
to diagnose pancreatitis
transient increase in activity of amylase with (2-12hrs)
acute pancreatitis
serum amylase may be raised in
bile duct obstruction & peptic ulcer
salivary gland diseases > raising the level of
amylase
hydrolytic enzyme, made by pancreatic acinar cells
lipase
digests fats into glycerol and fatty acids
lipase
lipase is made by
pancreatic acinar cells
normal lipase level
0-160U/L
amylase or lipase levels at least 3 times above the reference range are considered diagnostic of
acute pancreatitis
pancreatic lipase used to diagnose
Crohn’s disease, Cystic fibrosis, celiac disease
aldolase A predominates in
muscle
aldolase B predominates in
liver
aldolase C predominates in
brain
Aldolase A expression is repressed in
Adult liver
kidney and intestine
found in actin-containing filament of cytoskeleton, regulates cell contraction through its reversible binding to these filaments
Aldolase A enzyme
aldolase A (fructose-bisphosphate aldolase)
catalyzes the conversion of fructose-1,6-bisphosphate to glyceraldehyde 3-phosphate & dihydroxyacetone phosphate
aldolase A deficiency associated with
hemolytic anemia, myopathy
highest level of acid phosphatase found in
prostate cancer
moderate increase in PAP
diseases of bone ( Paget’s disease, osteoporosis) hyperparathyroidism, diseases of blood cells “sickle-cell disease or multiple myeloma”
lysosomal storage diseases (Gaucher’s disease)
more specific for screening or for detection early cancer
PSA
PSA is found in 2 forms in circulation
majority> complexed &some proteins
minor > free
enzymes used in chemotherapy
methotrexate (blocks the action of dihydrofolate reductase)
enzymes used in antibiotics
penicillin & vancomycin
enzymes used in pesticides
ACH E inhibitors
ACH E inhibitor is used in agriculture in the form of
organophosphate pesticides
An example of a toxic peptide (natural poisons) is
alpha-amanitin (death cap mushroom)
a potent enzyme inhibitor, preventing RNA polymerase II enzyme from transcribing DNA
alpha-amanitin
abnormal metabolism of carbohydrates
diabetes mellitus
abnormal metabolism of fats
tay sachs, niemann-pick diseases
abnormal metabolism of amino acids
alkaptonuria or albinism
(autosomal recessive rare disorder) affect the body ability to breakdown galactose (in milk) to glucose
galactosemia
galactose can cause damage to the
brain, kidney , liver and eyes
enzymes of the galactose metabolism
galactokinase, galactose-1-phosphate uridyltransferase and UDP-galactose 4-epimerase
function of G6PD
regenerates NADPH allowing regeneration of glutathione
glutathione function
protects against oxidative stress
lack of G6PD leads to
hemolysis
X-linked recessive disorder results in
defective glucose 6-phosphate dehydrogenase enzyme > non-immune hemolytic anemia
G6PD complications include
anemia & newborn jaundice q3
