enzymes &clinical enzymology
DESCRIPTION
ENZYMES &CLINICAL ENZYMOLOGY. Prepared by: Assistant professor Dr.Sumreena Mansoor. Vignette 5. Presenting complaint : A 50 year old man complains of severe retrosternal pain radiating to his left arm and jaw. - PowerPoint PPT PresentationTRANSCRIPT
ENZYMES &CLINICAL ENZYMOLOGY
Prepared by: Assistant professor Dr.Sumreena Mansoor
Vignette 5
• Presenting complaint: A 50 year old man complains of severe retrosternal pain
radiating to his left arm and jaw.
• Medical History: Severe chest pain on exertion that is relieved by sitting down. He
is hypertensive and is on ACE inhibitors for the last two years
• Examination: Anguished, dyspneic male, with hand clutched to chest. He is
nauseated and has vomited a few times.
• Family History: His father died of a Myocardial Infarction and his younger brother
is also taking ACE inhibitors.
• Investigations: EKG, CK-MB, LDH, Troponin I & T
• Emergency treatment: Injection streptokinase
• Diagnosis: Myocardial Infarction (MI)
ENZYME DIAGNOSTICS
ISOENZYMES
Catalyze the same reaction.
Differ in AA sequence and physical
properties
Separable on the basis of charge.
Are tissue specific.
IsoenzymesDifferent Isoenzymes may arise from
different tissues and their specific detection may give clues to the site of
pathology.
ENZYMES
NAME OF THE ENZYME PRESENT IN
Aspartate Amino transferase (AST)Serum glutamate-oxaloacetate transaminase (SGOT)
Heart and Liver
Alanine Amino transferase (ALT)Serum glutamate-pyruvate transaminase (SGPT)
Heart and Liver
Alkaline Phosphatase (ALP) Bone, intestine and other tissues
Acid Phosphatase (ACP) Prostate
glutamyl Transferase ( GT) Liver
Creatine kinase (CK) Muscle Including cardiac muscle
Lactate Dehydrogenase (LDH) Heart, liver, muscle, RBC
Amylase Pancreas
LACTATE DEHYDROGENASE (LDH)
Pyruvate Lactate (anaerobic glycolysis)
LDH is elevated in myocardial infarction, blood
disorders
It is a tetrameric protein and made of two types
of subunits namely H = Heart, M = skeletal
muscle
It exists as 5 different isoenzymes with various
combinations of H and M subunits
Isoenzyme name
Composition Composition Present in Elevated in
LDH1 ( H4) HHHH
Myocardium, RBC
myocardial infarction
LDH2 (H3M1) HHHM Myocardium, RBC
LDH3 (H2M2) HHMM Kidney, Skeletal muscle
LDH4 (H1M3) HMMM Kidney, Skeletal muscle
LDH5 (M4) MMMM Skeletal muscle, Liver
Skeletal muscle and liver diseases
LACTATE DEHYDROGENASE IN MI
Creatine kinase is a dimer made of 2 monomers
occurs in the tissues
Skeletal muscle contains M subunit, Brain contains
B subunits
Three different isoenzymes are formed
CREATINE KINASE (CK)CREATINE KINASE (CK)
Isoenzyme name
Composition Present in Elevated in
CK-1 BB Brain CNS diseases
CK-2 MBMyocardium/ Heart
Acute myocardial infarction
CK-3 MMSkeletal muscle, Myocardium
Alanine aminotransferase
(ALT)
Aspartate aminotransferase (AST)
ALANINE TRANSAMINASE (ALT) AND ASPARTATE TRANSAMINASE( AST)
- Oxoglutarate + L-aspartate
L- glutamate + oxaloacetate L - glutamate + pyruvate
- Oxoglutarate + L-alanine
Alanine transaminase (ALT) and Aspartate transaminase (AST)
enzymes are the most abundantly present in the liver and is
elevated in blood as a result of leakage from damaged cells
Alanine transaminase (ALT) increase is specific for liver
damage involving hepatocellular damage
Aspartate transaminase (AST) is moderately increased in
Muscular dystrophy and acute myocardial infarction
LEVELS OF ENZYMES IN DISEASES INVOLVING LIVER DAMAGE
In viral hepatitisRapid rise in transaminases (AST & ALT) in serum occurs even before bilirubin rise is seen
LEVELS OF ENZYMES IN MYOCARDIAL INFARCTION
CKCK-MB
AST
LDH
AST and CK rise in 6 hours following acute myocardial infarction
LDH are elevated much later and remains high for a longer period of days
SUMMARY Enzymes are biological catalysts present in every cell of the body.
An enzyme will act on a specific substrate yielding a product.
An isoenzyme is a genetic variant produced largely within a specific tissue.
Isoenzyme patterns can give information about organ-specific disease.
Important enzymes in the investigation of heart disease are CK, LDH and AST.
Important enzymes in the investigation of liver disease are AST, ALT.
Creatine kinase has three isoenzymes: CK-MM, CK-MB and CK-BB.
LDH has five isoenzymes.
Alkaline phosphatase can be used in the investigation of liver and bone disease.
Increased levels of acid phosphatase are found in prostate cancer.