Lecture: Clinically-Significant Enzymes Flashcards
Catalyzes the hydrolysis of various phosphoesters at an alkaline pH
Alkaline Phosphatase
Activator of ALP
Magnesium
What is the EC nomenclature of ALP?
EC 3.1.3.1
Most anodal isoenzyme of ALP
Liver ALP
Heat labile isoenzyme of ALP
Bone ALP
Heat stable isoenzyme of ALP
Placental ALP
Least anodal isoenzyme of ALP
Intestinal ALP
Rare variant of alkaline phosphatase
(ALP) that is found in some human tumors, particularly in urologic and gonadal cancers
Regan isoenzyme
Placental-like alkaline phosphatase
(ALP) that can be found in tumors, including those of the lung, breast, pancreas, and colon; known as germ cell alkaline phosphatase
Nagao isoenzyme
_ inhibits intestinal and placental
isoenzymes than the others
Phenylalanine
Common method of analysis of ALP; P-nitrophenyl phosphate → (yellow) p-nitrophenol anion; Measured at 405 nm
Bowers and McComb method
Beta-glycerophosphate → phenol + inorganic phosphate (via ALP)
Kay & Bodansky
Phenylphosphate → phenol + phosphate (via ALP)
King Armstrong Method
If residual ALP after heating is < 20% before
heating
Bone ALP
If after heating > 20% before heating
Liver ALP
Inhibits Nagao ALP
L-leucine
The presence of intestinal ALP isoenzyme in serum depends on _ and _
The blood group
Secretor status of the individual
A chronic disorder that causes bones to grow larger and become weaker than normal
Paget’s disease of bone
Bone mass decreases, but the ratio of bone mineral to bone matrix is normal
Osteoporosis
The ratio of bone mineral to bone matrix is low
Osteomalacia
Defective mineralization of the growth plate; seen in growing children
Rickets
Unmineralized organic tissue that eventually undergoes calcification and is deposited as lamellae or layers in the bone matrix
Osteoid
Absence of bone enzyme; hypophosphatemia
Inherited Hypophosphatasia
Catalyzes the same reaction made by ALP except that it is active at pH 5.0
Acid Phosphatase
EC nomenclature of ACP
EC 3.1.3.2
Thymol (measured) + phosphate (via ACP 5.4)
Thymolphthalein monophosphate
Inhibits prostatic ACP
L -tartrate
Inhibits RBC ACP
2% Formaldehyde
0.001M Cupric sulfate
Substrate: p-nitrophenolphosphate
Product: p-nitrophenol
Hudson
Substrate: Alpha-naphthylphosphate
Product: alpha- naphthol
Babson & Reed
Substrate: Thymolphthalein
monophosphate
Product: Thymolphthalein
Roy
Thymol + phosphate (colorless) + alkali → chromogen (measured); continuous monitoring method
Nitrophenyl phosphate
Better method presently used for ACP
Immunoassay–test for: PSA and P2- PSA
Result of a buildup of certain fatty substances in certain organs, particularly your spleen and liver
Gaucher’s Disease
Significance of ALP
Biliary tract obstruction by stones
Hepatocellular
Paget’s disease of bone
Osteomalacia
Rickets
Healing of bone fractions
Significance of ACP
Metastatic Prostatic Carcinoma
Forensic Clinical Chemistry
Benign Prostatic Hypertrophy (BPH)
Paget’s Disease
Cancers of breast with bone metastases
Gaucher’s Disease
Thrombocytopenic purpura
Enzyme to help diagnose Hairy Cell Leukemia
Tartrate Resistant ACP (TRAP)
ACP activity which can persist for up to
4 days
Also known as Serum Glutamate Oxaloacetate transaminase (SGOT); transfer of an amino group between aspartate and ketoacids with the formation of oxaloacetate and glutamate
Aspartate aminotransferase (AST)
L-glutamate + oxaloacetate (via AST)
L-aspartate + alpha-ketoglutarate
Malate + NAD+ + H2O (via MDH – malate dehydrogenase)
Oxaloacetate + NADH + H
The decrease in NADH concentration – measured at
340 nm
Coenzyme in the amino-transfer reactions & produces an increase in aminotransferase activity
Pyridoxal-5’-phosphate (P-5’-P) and its amino analogue, pyridoxamine-5’-phosphate
Uses malate dehydrogenase (MD) and
monitors the change in absorbance at 340nm; requires pyridoxal phosphate - coenzyme
Karmen
Methods of Analysis for AST
Karmen
Wroblewski and LaDue
Henry
Amador and Wacker
IFCC
Bergmeyer et. al
Also known as Serum Glutamate Pyruvate transaminase (SGPT); More liver-specific enzyme
Alanine aminotransferase (ALT)
Also known as Creatine Phosphokinase/ATP-Creatine-N-Phosphotransferase; Catalyzes the transfer of a phosphate group between creatine phospate and ADP
Creatine Kinase
EC nomenclature of CK
EC 2.7.3.2
Brain type; CNS, uterus, lungs, thyroid, and
intestines; associated with CNS disorders; CK1
CKBB
Hybrid type; Heart, tongue, esophagus-associated with heart muscle damage; CK2
CKMB
Muscle type; major isoenzyme; Heart and Skeletal muscles; CK3
CKMM
In the sera of healthy persons, _ form is the major isoenzyme
CKMM
Cardiac tissues contain significant quantities of _
CKMB
Allow determination of the enzyme activity of the B subunit of CK-MB and CK-BB; inhibits both M subunits of CK-MM and CK-MB
Immuno-inhibition technique (Anti-CK-M subunit antiserum)
Measure the concentration of
CK-MB using the “sandwich” technique
Mass immunoassays
The NADPH formed is detected by
observing the _ after excitation by _
Bluish-white fluorescence
UV light (360nm)
CK Activity is unstable – inactivation can be reversed by the addition of
Sulfhydryl compounds such as N-acetyl cystine or mercapto-ethanol
Most specific indicator of myocardial damage
CKMB
Genetic disorder characterized by progressive muscle degeneration and weakness due to the alterations of a protein called dystrophin that helps keep muscle cells intact
Duchenne Disorder
Hydrogen transfer enzyme that catalyzes the oxidation of L-lactate to pyruvate with the mediation of NAD+ as a hydrogen acceptor
Lactate dehydrogenase
EC nomenclature of LD
EC 1.1.1.27
Most anodal, myocardium, RBC, brain; HHHH
LD1
Myocardium and RBC, brain; HHHM
LD2
Brain and kidney; HHMM
LD3
Liver, brain, kidney; HMMM
LD4
Liver and skeletal muscle; MMMM
LD5
Alcohol dehydrogenase; drug toxicity and obstructive jaundice
LD6
The major isoenzyme of LD in the sera of
healthy persons
LD2
Most Anodal/ fastest migration LD
LD1
Least Anodal LD
LD5
Myocardial infarction, hemolytic anemia, and renal infarction
LD1 > LD2 (Flipped Pattern)
A sudden occlusion of a coronary artery by thrombus or by embolization
Acute Myocardial Infarction
Stroke or transient ischemic attack
Cerebrovascular Disease
Intermittent claudication (acute localized pain to arms and legs)
Peripheral Arterial Disease
Aneurysms or dissections
Aortic Atherosclerotic Disease
Disorder affecting the lumen of the arteries due to plaque buildup
Atherosclerosis
Disease affecting the walls of the arteries due to aging
Arteriosclerosis
A small heme protein found in skeletal and cardiac muscles; Earliest cardiac marker
Myoglobin
Complex regulatory proteins that bind to the thin filaments of cardiac muscles; Regulators of actin and myosin
Troponins (Tn)
Troponin that contains the binding sites for Ca2+ that help initiate contraction
Troponin C
Troponin that inhibits the interaction of myosin with actin
Troponin I
Troponin that binds the troponin components to tropomyosin
Troponin T
Most important marker for cardiac injury (AMI) – derived from heart muscles
TnT and TnI
Tropomyosin-binding subunit; Useful for assessment of early and late AMI
Troponin T
Inhibitory subunit or Actin-binding unit; Gold standard for AMI
Troponin I
Hydrolase that catalyze breakdown of starch and glycogen; Smallest enzyme; filtered by the glomerulus
Amylase
EC nomenclature of amylase
EC. 3.2.1.1
P form is also known as _
Amylopsin
S form is also known as _
Ptyalin
Fast migrator isoenzyme of amylase
Salivary Amylase
Slow migrator isoenzyme of amylase
Pancreatic Amylase
Measures disappearance of starch and measuring the amount of polysaccharide remaining; A starch-iodine reaction produces a blue iodine inclusion compound with amylose/amylase
Amyloclastic
Measures the appearance of the
product (reducing sugar) in a fixed time
Saccharogenic
Measures increasing color from production of product coupled w/ chromogenic dye
Chromogenic
Defined substrate used in coupled-enzymatic reactions
Enzymatic
Substrate cleaved by the amylase
ethylidene-pNP-G7
Substrates of Amylase
Maltopentaose
Maltotetraose
4-NP-glycoside
2-chloro-p-nitrophenyl-alpha-d-maltorioside (CNP-G3)
Amylase bound to immunoglobulins
Macroamylasemia
Inflammation of the parotid glands and is the most common inflammation of the major salivary glands
Parotitis
Increase AMS in urine
Pancreatitis
Decrease AMS in urine
Renal failure
Hydrolyses the ester linkages of fats to produce alcohols and fatty acids; the most specific pancreatic marker
Lipase
EC nomenclature of Lipase
EC. 3.1.3.3
Reference method of lipase
Cherry-Crandall Method
Symmetrical triglyceride derived from glycerol and three units of the unsaturated fatty acid oleic acid
Triolein
Measures directly free fatty acids by titrating with dilute alkali
Titrimetric
Measures the decrease of light scattering after hydrolysis to mono/diesters
Turbidimetric
Directly proportional to the LPS activity of the sample
Rate of methyl resorufin formation
How is lipase measured by spectrophotometric method?
Bluish-purple chromophore; peak
absorption at 580 nm
Inhibits lipase activity in serum
Hemoglobin
An enzyme found in the liver that serves most significantly as a marker of substance abuse; Regulates the transport of amino acids across cell membranes by catalyzing the transfer of a glutamyl group from glutathione to a free amino acid
Gamma Glutamyl Transferase
EC nomenclature of GGT
EC 2.3.2.1
GGT is measured by?
Szasz assay
Methods of analysis for GGT
Szasz
Rosalki & Tarrow
Orlowski
Catalyzes the first step in the hexose monophosphate pathway - conversion of glucose-6-phosphate to 6- phosphogluconate → NADPH
Glucose-6-Phosphate Dehydrogrenase
EC nomenclature of G6PD
EC 1.1.1.49
An acute hemolytic syndrome that occurs in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency following the ingestion of fava beans
Favism
True cholinesterase; red blood cells, lungs, spleen, nerve endings, gray matter of brain
Acetylcholinesterase (AChE)
Pseudocholinesterase; liver, pancreas, heart, white matter of brain, serum
Acylcholine acylhydrolase (PChE)
These 2 enzymes are significant tests for pesticide poisoning (cholinesterase inhibitors) and prolonged apnea after anesthesia
Pseudocholinesterase and Cholinesterase
An enzyme marker useful in diagnosis of hepatocellular jaundice and hepatobiliary from osseous diseases
5-Nucleotidase
Responsible for glycolytic breakdown of glucose to lactic acid
Aldolase
Isoenzyme of aldolase specific to skeletal muscle
Aldolase A
Isoenzyme of aldolase specific to WBC, liver and kidney
Aldolase B
Isoenzyme of aldolase specific to brain
Aldolase C