Enzymes Flashcards
CK isoenzyme found in highest concentration in the blood
CK-MM
Type of inhibition wherein the inhibitor attaches itself to the active site of the enzyme
Competitive
Inactive enzymes are termed as ___, which are common among digestive enzymes
Proenzymes
Most electronegative LD isoenzyme
LD1
What are the conditions for zero-order kinetics?
Substrate concentration is higher than enzyme concentration
Which LD isoenzyme appears indicative of arteriosclerotic cardiovascular failure?
LD6
This enzyme functions is maintain NADPH in a reduced form which is responsible for regenerating sulfhydryl-containing proteins (ie glutathione) from oxidized to reduced state
Glucose-6-phosphate dehydrogenase
The slowest moving fraction of CK is typically elevated in patients with:
Skeletal muscle disorders
Hemolyzed serum cannot be used for AST determination because:
Erythrocytes contain a large amount of AST
Correct arrangement of the classes of enzymes
Oxidoreductase, transferase, hydrolase, lyase, isomerase, ligase
Indicator enzyme used in Karmen method
Malate dehydrogenase
Chemical inhibition of ALP using Phenylalanine
Inhibits 75% of intestinal and 80% of placental ALP
Which enzyme is most useful in identifying the source of ALP elevation?
GGT
An amylase method which measures the disappearance of the starch substrate
Amyloclastic
What results when an enzyme is subject to post-translational modifications?
Isoform
Also known as organic cofactors
Coenzymes
What are the classes of enzymes?
Oxidoreductases Transferases Hydrolases Lyases Isomerases Ligases
In the Michaelis-Menten curve, Km is defined as the:
Substrate concentration at which v is half of Vmax
The Km of an enzyme reaction is ____ proportional to the affinity of a substrate to its enzyme.
Inversely
In this type of inhibition, increasing substrate concentration further increases inhibition.
Uncompetitive inhibition
1 IU can be defined as:
Amount of enzyme that will catalyze the reaction of 1 umol of substrate in 1 minute
1 Katal can be defined as:
Amount of enzyme that will catalyze the reaction of 1 mole of substrate in 1 second
1 IU = ___ kat
17
These conditions cause a pronounced elevation (>5x) in CK measurement.
DMD
Polymyositis
Dermatomyositis
Myocardial infarction
In AMI, CK-MB rises within ____ hours, peaks at ____ hours and return to normal within ____ hours.
4-8; 12-24; 48-72
The forward reaction of CK determination is also known as:
Tanzer-Gilvarg
The reverse reaction of CK determination is also known as:
Oliver-Rosalki (most commonly preferred)
Highest levels of LDH elevation are seen in:
Pernicious anemia & hemolytic disorders
These conditions cause a pronounced elevation (>5x) in LDH measurement.
Megaloblastic anemia Carcinomatosis Systemic shock Hepatitis Renal infarction TTP
These conditions cause a slight elevation (3x) in LDH measurement.
Liver disease
Nephrotic syndrome
Hypothyroidism
Cholangitis
The forward reaction of LDH determination is also known as:
Wacker et al
The reverse reaction of LDH determination is also known as:
Wrobleuski & :a Due
In AMI, LDH increases within ____ hours, peaks at ____ hours, and remains elevated for ____ days.
12-24; 72; 10
LD1 and LD2 are heat-____.
Stable
____ acts as the coenzyme for both AST & ALT.
Pyridoxal phosphate
In AMI, AST rises within ___ hours, peaks at ____ hours, and returns to normal in ___ days.
6-8; 24; 5
These conditions cause a pronounced elevation (>5x) in AST measurement.
Acute hepatocellular damage
MI
Circulatory collapse
IM
These conditions cause a slight elevation (>3x) in AST measurement.
Pericarditis Cirrhosis Pulmonary infarction Delirium tremens Cerebrovascular accident
Method of determination for AST
Karmen method
Method of determination for ALT
Walker et al
Highest activity of ALP is seen in:
Osteitis deformans (Paget’s disease)
These conditions cause a pronounced elevation (>5x) in ALP measurement.
Bile duct obstruction
Biliary cirrhosis
Osteogenic carcinoma
Hyperparathyroidism
Inhibition with ____ reduces the activity of I & P isoenzymes; inhibition with ____ reduces the activity of B & L isoenzymes.
Phenylalanine; levamisole
In Bessey-Lowry-Brock & Bowers-McComb ALP determination, ____ is the substrate used.
p-nitrophenylphosphate
In Shinowara-Jones-Reinhart ALP determination, ____ is the substrate used.
B-glycerylphosphate
In Babson & Reed ACP determination, ____ is the substrate used.
a-naphthylphosphate
In Roy ACP determination, ____ is the substrate used.
Thymolphthalein monophosphate
Most useful application for GGT measurement:
Detection of alcoholism & monitoring of alcohol consumption during treatment
In acute pancreatitis, AMY levels rises at ____ hours, peaks at ____ hours, remains elevated for ____ hours, and returns to normal within ____ days.
2-12; 24-30; 6-72; 3-5
These conditions cause a pronounced elevation (>5x) in AMY measurement.
Acute pancreatitis
Pancreatic pseudocyst
Morphine adminstration
What AMY method is used for stat analysis to rule out acute abdominal pain?
Turbidimetry & nephelometry
Somogyi unit is defined as the number of mg of glucose in ___ minutes at ___C under specific assay conditions.
30; 37
____ inhibits salivary amylase.
Wheat germ lectin
In electrophoresis , ____ amylase is more anodal.
Salivary
In acute pancreatitis, LIP levels rises at ____ hours, peaks at ____ hours, and remains elevated for ____ days.
2-12; 48-72; 10-14
In the Modified Cherry-Crandall method, ____ is used as the substrate instead of olive oil.
Triolein
G6PD deficiency is implicated in ____ anemia.
Drug-induced hemolytic
This type of cholinesterase hydrolyzes a variety of choline esters and provides a protective function in the body.
Pseudocholinesterase
In conditions such as ____, ACHE values are decreased.
Organophosphate poisoning
This is a sensitive, rapid, & the recommended method of ACHE determination.
Ellman
This is a temperature-sensitive method for ACHE determination, and confers much variability among different labs.
Michel
