Dr. Abir Alghanouchi Biochemistry department Sciences college

Transcription

1 Dr. Abir Alghanouchi Biochemistry department Sciences college

2 Blood plasma contains many enzymes which are classified into: 1. Functional plasma enzymes 2. Non functional plasma enzyme

3 Concentration in plasma Functional plasma enzymes Present in plasma in higher concentrations in comparison to tissue Non functional plasma enzymes Normally, Present in plasma in very low concentrations in comparison to tissue Function Have known functions Noknown functions Substrate Their substrates are always present in plasma Their substrates are absent from plasma Site of synthesis liver Different organs.g. liver heart, skeletal muscles and brain Effect of disease Decrease in liver disease Increase in different organ diseases Examples Clotting factors e.g. Prothrombin Lipoprotein lipase, Pseudocholinesterase ALT, AST, CK, LDH, alkaline phosphatase, acid phosphatase and lipase

4 Cell damagewith the release of its content of enzymes into blood e.g. Myocardial infarction and viral hepatitis Obstruction of normal pathwayse.g. Obstruction of bile duct increases alkaline phosphatase Increase of the enzyme synthesise.g. bilirubin increases the rate of synthesis of alkaline phosphatase in obstructive liver disease Increased permeabilityof cell membrane as in hypoxia

5 Measurement of non functional enzymes is important for: 1. Diagnosis of diseasesas disease of different organs cause elevation of different plasma enzymes 2. Prognosis of the diseasewe can follow up of the treatment by measuring plasma enzymes before and after treatment

6 AspartateTransaminase(AST)/ Glutamate oxaloacetate(got)

7 AlanineTransaminase(ALT)/ glutamate pyruvatetransaminase(gpt)

8 Lactate Dehydrogenase(LDH) Lactate Dehydrogenase O C O NADH + H + NAD + O C O C O HC OH CH 3 CH 3 pyruvate lactate

9 Abnormal plasma enzyme activities CreatineKinase(CK)

10 α-amylase hydrolyses alpha-bonds of large alphalinked polysaccharides such as starch and glycogen, yielding glucose and maltose

11 Gamma-glutamyl-transferase(GGT) carboxypeptidasewhich cleaves C-terminal glutamylgroups and transfers them to peptides and other suitable acceptors

12 Alkaline Phosphatase(ALP) Acid Phosphatase(ACP)

13 Isoenzymes(or isozymes) are a group of enzymes that catalyze the same reaction but they differ in amino acid sequence Because isoenzymesare originated from different tissues, their determination give more information than measurement of total enzyme activity in plasma

14 LDH occurs in 5 isoenzymes:ldh1 (H4), LDH2 (H3M), LDH3(H2M2), LDH4(HM3) and LDH5 (M4)

15 CK occurs in 3 isoenzymes, each is a dimer composed of 2 subunits (B& M): CK1= BB, CK2= MBand CK3= MM Each CK isozymeshows a characteristic electrophoretic mobility.

16 Liver Heart Pancreas Salivary Glands Bone Muscle Biliary Tract Prostate LDH 5 LDH 1 LPS AMS ALP CK ALP ACP ALT AST AMS GGT AST CK

17 1. Cardiac Disorders 2. Hepatic Disorders 3. Skeletal Muscle Disorders 4. Bone Disorders 5. Pancreatic Disorders 6. Salivary gland disease (Mumps) 7. Malignancies

18 e.g. Acute Myocardial Infarction (AMI) The myocardium becomes ischemic and undergoes necrosis. Cellular contents are released into the circulation. Blood levels of the following enzymes increase: AST LDH 1 CK

19 Myocardial muscle is the only tissue that contains high level of CK2(MB) isoenzyme. Appearance of CK2(MB) in plasma is specific for heart infarction. Following an acute myocardial infarction, CK2 appears in plasma 4-8 hoursfollowing onset of chest pain (peak is reached after 24 hours).

20 The CKrise the earliest, the LDHrise is latest The LDHelevations are present longer than those of CK and AST Fold elevation Days post infarction

21 HepatocellularDisorders 1. Viral hepatitis: Hepatitis B & Hepatitis C. 2. Toxic hepatitis: caused by chemicals & Toxins (e.g aflatoxin, Asp. flavus) Increased levels of the following enzymes : ALT AST LDH 5

22 Biliarytract disorders: The plasma levels of the following enzymes increase: ALP GGT

23 The plasma levels of the following enzymes increase: CK AST

24 Paget s Bone Disease: caused by increased osteoclastic activity. Rickets Osteomalacia The plasma levels of the following enzyme increase: ALP

25 The plasma levels of the following enzymes increase: Lipase AMS

26 The levels of α-amylase (AMS)is significantly increased

27 Plasma Acid phosphatase (ACP) levels increase in: 1. Prostatic carcinoma 2. Bone metastatic carcinoma Plasma levels of Alkaline phosphatase(alp) increase in: 1. Pancreatic carcinoma 2. Bile duct carcinoma 3. Liver metastasis

28 Plasma levels of Total Lactate dehydrogenase (LDH) increase in: 1. Leukemia 2. Lymphomas 3. Liver metastasis

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