1. Enzymes-3IsoenzymesClinical enzymology RITTU CHANDEL 05-02-13

2. ISOENZYMES Isoenzymes or isozymes are mutipleforms of same enzyme that catalysethe same chemical reaction Different chemical and physicalproperties: Electrophoretic mobility Kinetic properties Amino acid sequence Amino acid composition 2 3. S. Property E.g.No1ElectrophoreticIsoenzymes of Lactate dehydrogenase have mobility different electrophoretic mobility2Heat stability Alkaline phosphatase isoenzymes are eitherheat labile or stable3InhibitorAn inhibitor can inhibit only one isoenzymeof an enzyme eg. Acid phosphatase4Km Glucokinase and hexokinase5CofactorsMitochondrial isocitrate dehydrogenaserequires NAD+ , cytosolic form requiresNADP+6Tissue localisation LDH 1 is present in heart, LDH 5 in muscle7Antibodies For creatine kinase, each isoenzyme can bebound only by a specific antibody 3 4. Lactate dehydrogenase (LDH) E.C 1.1.1.27 L-lactate :NAD+ oxidoreductase:LDH Molecular weight- 134 kDa tetramer M (A) -muscle chromosome11(basic) H (B) -heart chromosome 12(acidic) 4 5. Lactate dehydrogenase (LDH)Normal valuesSerum -100 -200 U/LCSF - 7 -30 U/LUrine - 40 -100 U/L5 6. Isoenzyme Composition Electrophore Present in Elevated innametic migrationLDH 1 ( H 4) FastestMyocardium, myocardialHeat moving RBC,kidneyinfarctionresistantLDH2(H3M1)Myocardium, KidneyHeatRBC,kidneydisease,megaloresistant blastic anemiaLDH3(H2M2)brain Leukemia,malignancyLDH4(H1M3)Lung,spleen PulmonaryHeat labile infarctionLDH5 (M4)SlowestSkeletalSkeletal muscleHeat labilemoving muscle, Liver and liverInhibited bydiseasesurea6 7. Lactate dehydrogenase (LDH)This is an example in which two duplicated genes havebecome specialized to different tissues.The isozymes are also differentially expressed indifferent developmental stages. Before birth the heartis more anaerobic compared with adulthood. Indeed,before birth the main isozyme in the heart is the M4,and with time it switches to HM3 (at birth), to H2M2and HM3 at 1 year after birth, and to H3M AND H4after 2 years.My main LDH is HM3. Great! My main LDH is HM3 7 8. Atypical forms of LDH sixth isoenzyme LDH- X Seventh isoenzyme LDH -6 8 9. Clinical significance of LDH Myocardial infarction (LDH 1>LDH2) Megaloblastic anemia (50 times upperlimit of LDH 1 and LDH 2) Muscular dystrophy (LDH 5) Toxic hepatitis with jaundice (10 timesmore LDH 5) Renal disease- tubular necrosis orpyelonepheritis Pulmonary embolism LDH 3 (massivedestruction of platelets)9 10. Leukemia (LDH 2 and LDH 3) Malignancy (LDH 3) Hodgkins disease germ cell tumors Urinary LDH-3 to 6 times normal:chronic glomerulonephritisSystemic lupus erythematosusDiabetic nephrosclerosisBladder and kidney malignancies10 11. In CSF: Bacterial meningitis LDH 4 and LDH5 Viral meningitis - LDH 1 Metastatic tumors - LDH 5 Neonatal cases of intracranialhaemorrhage associated with seizuresand hydrocephalus 11 12. LDH in starch gelThe H(B) monomeris very negatively charged 12 13. CREATINEPHOSPHOKINASE Adenosine triphosphate:creatine N-phosphotransferase E.C-2.7.3.2 Dimeric enzyme (82 kDa) 4 -60 IU/L 13 14. 14 15. Enzyme unstable in serum Activity lost due to sulfhydryl groupoxidation at active site Dimer (each of 41000 Da)B (brain) chromosome 14M (muscle) chromosome 1915 16. IsoenzyCompome Present in Elevated insitionnameCK-1 Brain,prostate,GIFastBB tract,lung,bladder,uteru CNS diseasesmoving s,placentaCK-2Acute myocardial2% of MB Myocardium/ HeartinfarctiontotalCK-3 Skeletal muscle,SlowMM MyocardiummovingAll 3 in cytosol 16 17. 17 18. atypical forms of CK Fourth form - CK-Mt (chromosome 15)severe illnessMalignant tumors macroCKtype 1- CK BB complexed withIgG type 2-oligomeric CK-Mt18 19. Clinical significance of CK CK 1 elevated: very low birth weight newbornsbrain damage in neonatesneurological injury CK 1 rise inCSF >200 U/L die100 200 U/L survive withneurological defecitsALT)SerumtransaminasesHepatic carcinoma (5 -10 fold rise) Hepatobiliary disease Extrahepatic obstruction (10- 15 times)Serum alkalinephosphatases 49 50. Toxic hepatitis with jaundice (10 times moreSerum LDHLDH 5)Extrahepatic and intrahepatic causes (2 -6 fold incre 5nucleotidase Early infectious hepatitis Alcoholic cirrhosis and alcoholicsGamma glutamyl Hepatic carcinomatransferase 50 51. Serum enzymes in musclediseasesSerum aldolase Progressive muscular dystrophy muscular dystrophiesCPK myopathies hypothyroidism (5 fold more than normal value,also CK 2 is elevated)SGOT/SGPT Muscular dystrophy and dermatomyositis 51 52. Serum enzymes in bonediseases Pagets disease (10 25 times) Bone cancerAlkaline Healing of bone fracturephosphatase Osteomalacia and rickets Marker of bone disease-increases in: Acid giant cell tumor of bonephosphatase normal growing children 52 53. As tumor markers Aldolase-liver ALP bone,liver,leukemia,sarcoma Placental ALP ovarian,lung,hodgkins Amylase pancreatic CPK BB prostate,lung,breast,colon,ovarian GGT liver LDH liver,lymphoma,leukemia Neuron specific enolase tumors ofneuroendocrine origin 53 54. Prostate specific antigen (PSA orsemenogelase) From secretory epithelium of prostategland 32 kDa glycoprotein Mild Serine protease activity 1- 5 g/LLevels between 4 -10 g/L increased riskof prostate cancer >10 g/L - suggestive of Ca prostate >20 g/L - Ca prostate with metastases54 55. Enzymes-therapeutic agent1.Streptokinaseplasminogen streptokinase plasminfibrinsoluble product2.urokinase55 56. 3. Bacterial asparginase in leukemia4.- chymotrypsin-extraction of lens5.Chymotrypsin,papain antiinflammatory6.Collagenase debridment of dermalulcers7.Fibrinolysin venous thrombosis,pulmonary embolism8.Hyaluronidase rapid absorption ofdrugs injected subcutaneously56 57. 9.Lysosome antibacterial (eyeinfections)10.Trypsin clean woundstreatment of acutethrombophlebitis 57 58. Analytical use of enzymesas reagentsas labels58 59. AlcoholEthanoldehydrogenase LactateLactatedehydrogenase GlucoseGlucose oxidase and peroxidase UricaseUric acid UreaseUrea Cholesterol oxidase and peroxidase cholesterol59 60. As labels In immunoassaysfor determining concentration ofdrugs, hormones Glucose -6- phosphatedehydrogenase Alkaline phosphatase Beta galactosidase peroxidase60 61. BIBLOGRAPHY T.B. OF BIOCHEMISTRY: SATYANARAYAN VASUDEVAN PANKAJA NAIK RANA SHINDE TEITZ HARRISON-INTERNAL MEDICINE THANK YOU 61