Presentation on theme: "Objectives List the clinically important enzymes and isoenzymes."— Presentation transcript:
1Clinical (Diagnostic & Therapeutic ) importance of Enzymes and isoenzymes
2Objectives List the clinically important enzymes and isoenzymes. State which of the enzymes and isoenzymes are found in which tissuesOutline different ways of measuring plasma enzymeDescribe plasma enzyme changes in different diseases.
3Circulatory system enzymes serum enzymes Functional serum enzymeresponsible for reaction taking place in blood e.g; clotting of bloodNon functional serum enzymesdo not have their function in blood but they are present because of wear and tear of the tissue IN CONSTANT levelMeasurements of the activity of enzymes in plasma are of value in the diagnosis and management of a wide variety of diseasesSmall amounts of intracellular enzymes are present in the blood as a result of normal cell turnover. When damage to cells occurs, increased amounts of enzymes will be released and their concentrations in the blood will rise.
4INTRODUCTIONInjury or death of tissues can cause the release of tissue-specific enzymes into the bloodstream.Elevated enzyme levels are often indicators of tissue problems, and are used in the diagnosis of diseases.Enzyme activities in the body fluids are altered by pathological processes so, its measurement is used for disease investigation.Serum enzyme level may be increased by disease that cause increase in its rate of release or decrease in their rate of excretion.
5Measurement of serum enzymes Enzymes are normally intracellular and LOW concentration in blood.Enzyme release (leakage)in the blood indicates cell damage (cell –death, hypoxia, intracellular toxicity)Quantitative measure of cell/tissue damageOrgan specificity- but not absolute specificity in spite of same gene content.Most enzymes are present in most cells-differing amountsTime course of disease
6Enzymes routinely measured NAME OF THE ENZYMEPRESENT INAspartate Amino transferase (AST)Serum glutamate-oxaloacetate transaminase (SGOT)Heart and LiverAlanine Amino transferase (ALT)Serum glutamate-pyruvate transaminase (SGPT)
7Enzymes routinely measured NAME OF THE ENZYMEPRESENT INAlkaline Phosphatase (ALP)Bone, intestine and other tissuesAcid Phosphatase (ACP)Prostate glutamyl Transferase ( GT)LiverCreatine kinase (CK)Muscle Including cardiac muscleLactate Dehydrogenase (LDH)Heart, liver, muscle, RBC AmylasePancreas
9Enzyme Assays that are Carried out in Mayocardial Infarction Commonly done:Creatine kinase (CK)Aspartate Amino transferase (AST)Lactate Dehydrogenase (LDH)
10Myocardial Infarction ( MI ) Necrosis of the myocardium, but not angina pectoris release of CK, AST and LDH into the circulation.CK is the first to rise (activity within 6 h of MI ).Total CK reaches a peak at h.In uncomplicated cases, CK returns to normal within 3 days.
11Myocardial Infarction ( MI ) Serum AST more slowly ( maximum activity within 48 h) and returns to normal in 4-5 days.No significant elevation in LDH seen for the 1st 24 h (reaches maximum at about 3 days & remain for up to 8 days).The enzyme is relatively non specific to myocardial tissue.
13Liver Enzymes ( ALT, AST, GGT, ALP, LDH) Measurement of serum enzyme activities for :a - Differential Diagnosis of Jaundice.b - Monitoring of drug toxicity.ALT is more specific than AST.Hepatocellular disease has only modest effect on ALP & GGT (up to 3 times the upper limit of normal)In Cholestasis, Higher values of ALP & GGT due to synthesis
14Alanine aminotransferase (ALT) Widely distributed, although the largest amounts found in the liver.Smaller amounts occur in the heart but usually remains normal after MI .Congestive cardiac failure release from the liverMore specific for liver disease than AST.
15Aspartate aminotransferase (AST) This enzyme is widely distributed in the body.Main sources: Heart, liver, skeletal muscle, and kidney.Useful in the diagnosis of MI, liver disorders and muscle damage.Causes of serum AST levels:.Liver diseases: Hepatitis, hepatic necrosis , cholestasisCardiac disease: Myocardial Infarction.Diseases of skeletal muscle: Crush injury,trauma,myopathyFrom Erythrocytes: Hemolysis
16Alkaline phosphatase (ALP) Widely distributed, high concentrations in intestines, liver, bone, spleen, placenta and kidney.The main sources of serum ALP are the hepatobiliary tree and bone disorders.Elevated levels during healing of fractures , active growth and during the 3rd trimester of pregnancy. serum ALP activity in liver disease is mainly due to Cholestasis.Decreased levels are found in the inherited condition
17Bone Enzymes - ( Alkaline Phosphatase) ALP ALP enzyme is usually normal in Osteoporosis as osteoblastic activity is not increasedModest of ALP in Osteomalacia and RicketsHealing fractures Transient of ALP1ry & 2ry Hyperparathyroidism of ALPIn Paget’s disease of bone of ALP (10 times)1ry & 2ry bone tumors of ALP (5 times normal)
18Alkaline phosphatase (ALP) Causes of increased serum alkaline phosphatase enzyme activity:Physiological :Bone disease:Hepatobiliary disease:Others:- Infancy- Puberty- Pregnancy- Intestinal isoenzymes- Hyperparathyroidism- Osteomalacia, rickets- Paget’s disease of bone- Osteomyelitis- Hepatitis- Cholestasis- CirrhosisCarcinoma of the bronchus
19Acid phosphatase (ACP) Found in prostate, bone, liver, spleen, kidney, RBCs and plateletsPrimarily used to diagnose prostate cancer . In other prostatic conditions e.g. prostatitis, benign prostatic hypertrophy.In other non prostatic conditions e.g. hemolysis, Paget’s disease, metastatic carcinoma of the breast & Gaucher’s disease.Prostate- Specific Antigen(PSA): an enzyme occurs in prostatic tissue and in cases of metastatic carcinoma
20Amylase (AMS) HYDROLASES THAT SPLIT COMPLEX POLYSACCHARIDES. - CA+2 REQUIRING METALLOENZYMENORMAL LEVEL: U/L INCREASES DRASTICALLY IN ACUTE PANCREATITIS ALSO IN MUMPSSOURCES :1. PANCREAS (P-TYPE)2. SALIVARY GLANDS (S-TYPE)3. INTESTINAL MALIGNANCY CLINICAL SIGNIFICANCE : DIAGNOSIS AND MONITORING OF PANCREATITIS
21Lipase (LPS)Breaks down fat into monoacylglycerol and free fatty acids.Primarily from the pancreas.Used to diagnose acute pancreatitis.Pancreatic lipases :Almost exclusively used clinically in the investigation of pancreatitis.- Increase within hours of acute attack.- May remain elevated for many days .- More specific to acute pancreatitis than amylase.
22Specificity of Enzymes : Greater specificity is achieved in three ways:Interpreting investigations in the light of clinical featuresIsoenzyme determination: AST may be due to MI or Hepatitis so, it makesconfusion in diagnosis to be confirmed by LDH levels.- ALP in Cholestasis & bone diseases :- Differentiated by bilirubin & transaminase levels in Cholestasis .- Confirmed by GGT in Cholestasis.
23Conditions in which level of activity in serum is elevated NAME OF THE ENZYMEConditions in which level of activity in serum is elevatedAspartate Amino transferase (AST)Serum glutamate-oxaloacetate transaminase (SGOT)Myocardial infarction, Liver disease especially with liver cell damageAlanine Amino transferase (ALT)Serum glutamate-pyruvate transaminase (SGPT)Liver disease especially with liver cell damageAlkaline Phosphatase (ALP)Liver disease- biliary obstructionOsteoblastic bone disease-rickets
24Acid Phosphatase (ACP) Prostatic carcinoma glutamyl Transferase ( GT)Liver disorder like liver cirrhosisCreatine kinase (CK)Myocardial infarction and skeletal muscle disease(muscular dystrophyLactate Dehydrogenase (LDH)Myocardial infarction, other diseases like liver disease.some blood diseases AmylaseAcute pancreatitis
25ISOENZYMES Catalyze the same reaction Two or more polypeptide chains Different polypeptide chains are products of different genesDiffer in AA sequence and physical propertiesMay be separable on the basis of chargeAre tissue specific
27LACTATE DEHYDROGENASE (LDH) converts pyruvate to lactate (and vice versa)LDH occurs as a tetramer of 2 different subunits H & M:(product of 2 diff. gene)normal LDH2 is high in serum but after MI LDH1 risesincrease of total is seen inhemolytic anemia,hepatocellular damage,carcinomas,leukemias & any condition of necrosis.
28, five isoenzymes of LDH that occurs as a dimer of 2 different subunits H &M
30Creatine kinase (CK)Creatine kinase is associated with ATP regeneration in muscle and nervous tissue.Elevated blood levels of CK are used as indicators of MI, muscular dystrophy, and stroke.CK occurs as a dimer of 2 different subunits, M and B. - CK-BB: Brain . - CK-MB: cardiac muscle. - CK-MM: Muscle type.CK-MB is released from cardiac muscle cells after MI.
32„ Cardiac enzymes“The figure is adopted from the book: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, ISBN 0‑471‑15451‑2
33ENZYMES IN THERAPYSubstitution of missing production of digestive enzymes – digestive enzymes – pepsin trypsin…Removal of deposits of death tissue or fibrin (e.g. in lungs, eyes), treatment of skin defects – proteinases, nucleases, collagenaseAcceleration of fibrinolysis in lungs embolization (activation of plasmin and plasminogen) –streptokinase, urokinase
35Quiz1.An activated enzyme consisting of polypeptide chain and a cofactor is called:A.Apoenzyme B.Holoenzyme2.Which one forms the raw material for coenzymes?A.Viitamins B.Carbohydrates3.A cofactor made of inorganic ion which is detachable is calledA.Prosthetic group B.Coenzyme
364. Enzymes _________ the activation energy of a chemical reaction A.Increases B.Decreases5. Three dimensional dcavity bearing a specific charge by which the enzyme reacts with its substrate is calledA.Active site B.Binding site6. Which step causes activation of catalytic site of an enzyme?A.Change in pH of the surroundings.B.Formation of Enzyme Susstrate complex
377. If the concentration of enzyme is kept constant and amount of substrate is increased a point is reached where increase in substrates concentration does not affect the reaction rate because ofA.Enzymes get denatured at higher substrate conc.All the active sites on enzyme molecule are occupied.
387. f more substrate to already occurring enzymatic reaction is added and there is no effect on the rate of the reaction what is the form given to this situation:A.Saturation B.Denaturation8.Optimal temperature of enzymes present in human body isA.27C B.37C
399. A chemical substance which can react (in place of substrate) with the enzyme but is not transformed into product/s and thus blocks the active site temporarily or permanently is calledA.Co-enzyme B.Blocker C.Inhibitor10 The structure of an enzyme is altered by:A.Irreversible inhibitor B.Reversible inhibitor