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Biochem Isoenzymes.ppt
- 1. IsoEnzymes Dr Rina Das Mehta Professor MM College of Pharmacy, MM(DU)
- 2. Isoenzymes • Isoenzymes – are enzymes that differ in amino acid sequence but catalyze the same chemical reaction. • They have similar catalytic activity, but are different biochemically or immunologically. • Different forms may be differentiated from each other based on certain physical properties • electrophoretic mobility, • differences in absorption properties • or by their reaction with a specific antibody
- 3. Creatine Kinase (CK) • Action –This enzyme is associated with the regeneration and storage of high energy phosphate (ATP). • It catalyzes the following reversible reaction in the body.
- 4. Creatine Kinase (CK) • High concentrations of CK in: • skeletal muscle, • cardiac muscle • and brain tissue • Increased plasma CK activity is associated with damage to these tissues • CK is especially useful to diagnose: • Acute Myocardial Infarction (AMI) • Skeletal muscle diseases ( Muscular Dystrophy )
- 5. Creatine Kinase (CK) • CK has 3 isoenzymes • Each isoenzyme is composed of two different polypeptide chains (M & B) •CK - BB (CK1) Brain type •CK - MB (CK2) Cardiac type or hybrid type •CK – MM (CK3) Muscle type • Normal serum consists of approximately 94% to 100% CK-MM • Cardiac muscle CK is 80% CK-MM and 20% CK-MB
- 6. Creatine Kinase (CK) • BB migrates fastest to anode than MB & MM • The major isoenzyme in the sera of healthy people is the MM form. • Values for the MB isoenzyme range from undetectable to trace (<6% of total CK). • It also appears that CK-BB is present in small quantities in the sera of healthy people
- 7. Diagnostic Significance • The value of CK isoenzyme separation can be found principally in detection of myocardial damage. • Cardiac tissue contains significant quantities of CK-MB, approximately 20% of all CK-MB. • increased CK – MB ( > 6% of the total CK activity ) is a strong indication of AMI • Post AMI CK-MB • CK-MB increases 4 – 8 hours postAMI • Peaks at 12 - 24 hours postAMI • Returns to normal 48 - 72 hours
- 8. Lactate Dehydrogenase (LDH) • Catalyzes interconversion of lactic and pyruvic acids • It is a hydrogen-transfer enzyme • NAD is used as coenzyme • High activities in heart, liver, muscle, kidney, and RBC • Lesser amounts: Lung, smooth muscle and brain
- 9. LDH Isoenzymes • Because increased total LDH is relatively non-specific, LDH isoenzymes can be useful • 5 isoenzymes composed of a cardiac (H) and muscle ( M ) component • LD - 1 ( HHHH ) Cardiac , RBCs • LD - 2 ( HHHM ) Cardiac , RBCs • LD - 3 ( HHMM ) Lung, spleen, pancreas • LD - 4 ( HMMM ) Hepatic • LD - 5 ( MMMM ) Skeletal muscle • LD-1 is the fastest towards the anode
- 10. Diagnostic Significance • LDH is elevated in a variety of disorders. • in cardiac, • hepatic, • skeletal muscle, • and renal diseases, • as well as in several hematologic and neoplastic disorders • The highest levels of LD-1 are seen in pernicious anemia and hemolytic disorders • LD-3 with pulmonary involvement • LD-5 predominates with liver & muscle damage
- 11. Diagnostic Significance • In healthy individuals • LD-2 is in highest quantity then LD-1, LD-3, LD-4 and LD-5 • Heart problems: 2-10 x (Upper Limit of Normal) ULN in acute MI • If problem is not MI, both LD1 and LD2 rise, with LD2 being greater than LD1 • If problem is MI, LD1 is greater than LD2. • This is known as a flipped pattern
- 12. Aspartate Aminotransferase (AST, SGOT, GOT) •The transamination reaction is important in intermediary metabolism because of its function in the synthesis and degradation of amino acids. •The ketoacids formed by the reaction are ultimately oxidized by the tricarboxylic acid cycle to provide a source of energy.
- 13. Diagnostic Significance • The clinical use of AST is limited mainly to the evaluation of hepatocellular disorders and skeletal muscle involvement. • Post AMI • Rises 6 – 8 hours • Peaks at 24 hours • Returns to normal by day 5 • AST levels are highest in acute hepatocellular disorders, viral hepatitis, cirrhosis. • Viral hepatitis may reach 100 x ULN