Partial 2 - Enzymes Flashcards
IU/L
Amount of enzyme necessary to catalyze the conversion of 1μmol of substrate per minute
SI unit (mol/sec)
Amount of enzyme that will catalyze the conversion of one nanomole of substrate per second (nanokatal)
Enzyme concentration may change if:
- Tissue is undergoing injury
- Tissue is under stress - corrective response
- Tissue is under direct damage: reversible - small molecules; permanent - total leakage
- Tissue Stimulation
- Tissue Proliferation - natural cell turnover
How many isoenzymes Lactose dehydrogenase have?
5, LDH1 - LDH5
Where in the cell is LDH found and what is the function
Found in cytoplasm of every cell and it catalyze important step glycolysis
LDH subunits
H (heart) subunit (gene on chromosome 12)
M (muscle) subunit (gene on chromosome 11)
Creatine Kinase (CK) location in cell
Mitochondria
CK function
Function in muscle cells to catalyze the transfer of high energy bond from ATP to creatine and irreversible reaction during active muscle contractions
CK isoenzymes and their distributions
CK-MM - heart (79%) and muscle (99%)
CK-MB - trace level in muscle (1%) and high level in myocardium (20%)
CK-BB - throughout the brain (97%) and muscles (1% - cardiac muscle)
First sign of acute MI biomarkers
First sign is increased myoglobin (small size) and CK-MB isoforms (normal serum trace levels)
CK-MB :
Beginning of elevation
Max. peak
Presence
Beginning of elevation: 3-12h
Max. peak: 8-24h
Presence: 36-48h
Troponins:
Beginning of elevation
Max. peak
Presence
Beginning of elevation: 3-12h
Max. peak: 8-24h
Presence: <10 days
Myoglobin:
Beginning of elevation
Max. peak
Presence
Beginning of elevation: 1-4h
Max. peak: 6-7h
Presence: <24h
LDH:
Beginning of elevation
Max. peak
Presence
Beginning of elevation: 6-12h
Max. peak: 24-48h
Presence: 6-8 days
Skeletal muscle disease useful biomarkes
CK
Acute muscle enzyme release causes
Surgery Trauma Crush injuries Excessive muscular contractions Hyperthermia Viral myositis Toxins exposure
Muscular dystrophies
Higher portion of CK-MB in muscle than normal (high tissue turnover)
Long distance runners
High non-cardiac CK-MB
Amylase (Amyl) isoenzymes
Pancreas, salivary gland, testis, ovary
Amylase reference range
20-160 U/L
Lipase (Lip) reference
<200 U/L
Acute pancreatitis diagnosis
- Amylase and lipase level increases after few hours after onset, remain elevated for 36-48h, activity isn’t correlated with severity
- Clinical sensitivity for amylase and lipase - 90% when blood is sampled in the first 36h
Pancreatic enzymes in other disorders
Pancreatic trauma Abdominal surgery Carcinoma Diabetes mellitus Viruses injury Drugs Perforated ulcer Peritonitis Renal failure (Amylase and trypsin are excreted with urine)
Liver Function Tests
- ALT or SGPT
- AST or SGOT
- LDH
- ALP, GGT
- Bilirubin (total and direct)
- Total protein (albumin and globulins)
- Albumin (main protein made by liver)
- PT (pro-thrombin time)