Serum Enzymes Flashcards
What is the reference range for ALP
30-130 U/L
What is the reference range for LD
100-225 U/L
What is the reference range for ALT
Female <40 U/L
Male < 60 U/L
What is the reference range for AST
Female <35 U/L
Male <45 U/L
What is the reference range for CK
Female <200
Male <250
What is the reference range for GGT
<80 U/L
What is the reference range for AMY
30-150 U/L
What is the reference range of LIP
0-60 U/L
What is activation energy
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
What is an isoenzyme
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
What is a cofactor
non-protein molecules needed for enzyme activity
What is an activator
inorganic cofactor that when bound to an enzyme icreases the enzymes activity
What is a coenzyme
organic, low molecular weight substances which combines with an inactive protein
What is an apoenzyme
an inactive form of an enzyme that requires a coenzyme to be converted into an active holoenzyme
What is a prostetic group
a coenzyme bound to an apoenzyme
What is a holoenzyme
the active form of an apoenzyme formed by the combination of the apoenzyme with its coenzyme
What is denaturation
a change in the structure of a protein accompanied by a loss of activity
What are causes of denaturation
extreme pH, elevated temperature, changes in ionic strength and chemical modifiers
What are enzymes
proteins that function as catalysts by lowering the activation energy
What is the optimum pH for most physiological enzymes
7.0-8.0
What do buffers do
control the pH of enzyme reactions
What is the optimal temperature for physiological enzymes
37C
What does a 10C increase in temperature do to the reaction rate
doubles it
What is the rate of reaction dependant on in zero order kinetics
enzymes
What is the rate of reaction dependant on in first order kinetics
substrate
What is competitive inhibition
the inhibitor is a structural analog of the substrate and competes for the active site
How do you overcome competitive inhibiton
adding more substrate
What type of inhibition is competitive inhibition
reversible
What is non-competitive inhibition
an inhibitor binds tot he enzyme at an allosteric site causing conformational changes in the enzyme structure
What is uncompetitive inhibition
the inhibitor binds to the enzyme-substrate complex preventing the creation of products
How are enzymes measured
the concentration of an enzyme is directly proportional to the measurable catalytic activity of the enzyme
What are fix time methods
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
What are continuous monitoring methods
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
Where is ALP found
intestine, liver, bone and placenta as well as the surface of RBCs
What is the significance of ALP
clinically significant sources are osteoblasts and hepatocytes, increased in bone diseases and liver issues as well as in dialysis patients and cancer
What are the activators of ALP
zinc and magnesium
What are the inhibitors of ALP
phosphate and anticoagulants
What are the limitations of ALP testing
measurement should occur within 4 hours, ALP increases at 4C and RT, hemolysis is an interference
What is the tissue distribution of LD
throughout the body though concentrated into the heart, liver, skeletal muscles, RBC, platelets and lymph nodes
What is the clinical significance of LD
increased in hemolytic and megaloblastic anemia as well as in liver disease and myocardial infarction
What is the coenzyme of LD
NAD
What are the limitations of LD testing
a serum sample is prefered and samples should be stored at RT, hemolysis is an interference
What is the tissue distribution of ALT
liver and kidneys
What is the clinical significance of ALT
increased in hepatic diseases
What is the coenzyme of ALT
vitamin B6
What are the limitations of ALT testing
should be measured on the same day as collection, only stable at -70C, hemolysis is an interference
What is the tissue distribution of GGT
kidney, bile ducts of liver, pancreas and liver
What is the clinical significance of GGT
indicator of hepatobiliary disease, elevated in alcohol related issues
What is the activator for GGT
magnesium
What are the inhibitors of GGT
citrate, oxalate, fluoride
What are the limitations of GGT testing
serum and plasma are stable at 4C, ethanol warfarin phenobarbital and phenytoin can cause a false increase
What is the tissue distribution of CK
skeletal muscle, heart, brain
What is the clinical significance of CK
skeletal muscle diseases and heart disease
What is the activator of CK
magnesium
What is the coenzyme of CK
ATP
What are inhibitors of CK
All coagulants except heparin, Maganese, calcium, zinc, copper and excess magnesium
What are limitations of CK testing
samples are stable for upto 48 Hr at 4C, hemolysis will intefere
What is the tissue distribution of amylase
salivary glands, pancreas, ovaries, fallopian tubes and lungs
What is the clinical significance of amylase
increased in salivary gland inflammation, acute pancreatitis and other intra-abdomin disorders
What is the activator for amylase
calcium
What are the inhibitors for amylase
all anticoagulants except heparin
What are the limitations of amylase testing
stable at RT, morphine and opiates elevate
What is the tissue distribution of lipase
pancreas, stomach and small intestine
What is the clinical significance of lipase
elevated in acute pancreatitis, gastic or duodenal ulcers and intestinal obstruction
What is are the cofactors of lipase
colipase and bile salts
What are the limitations of lipase testing
stable at RT for 1 week, hemolysis is an inhibitor
