Enzyme Clinical Application Biochemistry Department Level 1 Lecture No :4 Date : / 1 / 2015 Enzyme Clinical Application Dr. Marwa Matboly Armed Forces College Of Medicine Biochemistry Department

Enzymes O - C Hi, Everybody! 。

Intended learning outcomes(ILO) List some examples of drugs acting by competitive enzyme inhibition and others acting as irreversible enzyme inhibitors. Summarize the various methods of enzyme regulation. Describe the clinical importance of non functional plasma enzymes. State the diagnostic importance of LDH, CPK, and alkaline phosphatase isoenzymes. Explain the importance of enzymes as therapeutic agents.

Objectives Enzymes as Biological Catalysts The Properties of Enzymes Enzyme classification Enzyme kinetics Factors affecting enzyme activity Enzyme Inhibition Regulation of enzyme activity. Applications of Enzyme Action

Enzymes in clinical medicine Diagnosis and prognosis of various diseases Non functional plasma enzymes Therapeutic agents

Enzymes in clinical medicine 1-plasma enzyme as diagnostic and prognostic yool

1-Diagnosis of various diseases Plasma enzymes Isoenzymes

Lactate dehydrogenase Diagnosis of diseases Plasme enzymes Functional Non functional Isoenzymes Lactate dehydrogenase Creatinine kinase

Functional Plasma Enzymes Non-Functional Synthesis by the liver Intracellular enzymes Different body organs (Released by normal cell turnover) Function Perform specific functions in blood No physiological function in blood Substrates In blood Present Absent Plasma levels Higher than those in tissues Very low under normal conditions They increase only in case of tissue damage; myocardial infarction ,hepatitis, cancer. Examples Enzymes of blood coagulation and fibrinolysis, Lipoprotein lipase, Lactate dehydrogenase Creatinekinase Transaminases Alkaline phosphatase

Enzymes of diagnostic importance Diagnostic use Amylase and lipase Pancreatitis Acid phosphatase Prostate cancer Alk.phosphatase Bone , liver diseases and hyperparathyroidism Creatine kinase Recent myocardial infarction Lactate DH. myocardial infarction liver diseases, Leukemia Transaminases myocardial infarction(SGOT) liver diseases(SGPT)

Indicator of cellular damage Non functional plasma enzymes are present in higher concentration in cells compared to extracellualr fluid Increased activity of non functional plasma enzymes in extracellular fluid Indicator of cellular damage

Amount of non functional plasma enzyme released is proportionate to the degree of cellular damage

Non functional plasma enzymes Unfortunately, there are few enzymes that are organ or tissue specific. Examples: Alcohol dehydrogenase in liver Acid phosphatase in prostate Pancreatic amylase and lipase

Isoenzymes Study of isoenzyme increases the specificity of non functional plasma enzymes for various tissue They are different molecular forms of the same enzyme synthesized by different tissues

Same Different Isoenzymes Catalyze the same reaction Act on the same substrate Use the same coenzymes Same Subunits Vmax and Km Physical properties Electrophoretic mobility, Immunogenic properties Heat stability Different

Examples of clinically important isoenzymes: 1-Lactate dehydrogenase 2-Creatinekinase. 3-Alkaline phosphatase

LDH1(HHHH) specific for HEART Lactate dehydrogenase has Five isoenzymes present in blood LDH1(HHHH) specific for HEART LDH2(HHHM) " " RBCs LDH3(HHMM) " " BRAIN LDH4(HMMM) " " LIVER LDH5(MMMM) " " MUSCLE

Electrophoresis of LDH In myocardial infarction :Total serum LDH level increases due to elevation of LDH1 (cardiac) isozyme, electrophoresis is important to detect which fraction increased

Three isoforms are present -CK 1 (BB) (Brain) -CK2 (MB) (Heart) Creatinekinase(CK) Three isoforms are present -CK 1 (BB) (Brain) -CK2 (MB) (Heart) -CK3 (MM) (Skeletal muscle) In myocardial infarction there is elevation of total CK with marked elevation of CK2 (MB) after 4-8 hours electrophoresis is important to detect which fraction increased

CK2 is used for early detection LDH1 for follow up In myocardial infarction, the cardiac isoenzymes of both CK&LDH are increased , CK2 rises within 4-8 hours after the onset of pain reaches peak within 24 hours. It returns to normal level after two-three days. LDH1 reaches its peak after 36-40 hours returns to normal level after 48 hours

Alkaline phosphatase ALP isoenzymes, present in blood, are derived from bone, liver, intestine, or placenta of pregnant woman Electrophoretic separation of isoenzymes(different numbers of sialic acid residues) is performed to determine the organ affected.

Increased ALP Normal elevation Moderate increase Very high level Pregnant women Growing children Adolescent Moderate increase Liver disease e.g. hepatitis ,obstructive jaundice Very high level Bone disease e.g. ricket, osteomalacia and cancer

Enzymes in clinical medicine Therapeutic agents

Enzyme prepared from streptococcus Some enzymes are used as Therapeutic agents ♥ Streptokinase: Enzyme prepared from streptococcus Used in clearing blood clots in myocardial infarction Act by activating plasminogen to form plasmin. Plasmin cleaves fibrin into several soluble components

Plasminogen Sterptokinase Plasmin FDP Fibrin

Asparginase is administrated decreasing asparagine level ♥ Asparaginase: enzyme used in therapy of adult leukemia ,. Tumor cells have nutritional requirement for asparagine, Asparginase is administrated decreasing asparagine level Asparginase depresses the viability of tumor

Asparginase Aspargine is required as nutrition for tumor cells Aspargine Aspartic acid Aspargine is required as nutrition for tumor cells Asparginase used in treatment of Leukaemia

Use of asparginase will decrease aspargine level so inhibiting tumor growth (depress the tumor vitality). Leukemic cells have little or no ability to synthesize asparagine and must scavenge it from blood to synthesize their proteins