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Enzymes Dr. Noha Soliman.

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Presentation on theme: "Enzymes Dr. Noha Soliman."— Presentation transcript:

1 Enzymes Dr. Noha Soliman

2 Enzyme Regulation

3 1.Feedback control: Regulation process where the product of a series of enzyme-catalyzed reactions inhibits an earlier reaction in the sequence.


5 3.Isozymes or Isoenzymes:
Different form of the same enzyme. They perform the same catalytic function. (Catalyze same reactions but are formed from structurally different polypeptides). Different Isoenzymes may arise from different tissues and their specific detection may give clues to the site of pathology.

6 Functional plasma enzymes
( Plasma derived enzymes) Certain enzymes, proenzymes, and their substrates are present at all times in the circulation of normal individuals and perform a physiologic function in the blood. Examples of these functional plasma enzymes include the proenzymes of blood coagulation. The majority of these enzymes are synthesized in and secreted by the liver. Nonfunctional plasma enzymes (Cell derived enzymes) -Plasma also contains numerous other enzymes that perform no known physiologic function in blood. Arise from the routine normal destruction of erythrocytes, leukocytes, and other cells.

7 Tissue damage or necrosis resulting from injury or disease is generally accompanied by increases in the levels of several nonfunctional plasma enzymes.

8 Enzymes as Diagnostic tools

9 How? of numerous enzymes has been shown
The measurement of the serum levels of numerous enzymes has been shown to be of diagnostic significance. This is because the presence of these enzymes in the serum indicates that tissue or cellular damage has occurred resulting in the release of intracellular components into the blood &this increases the level of certain enzymes in blood according to the damaged organ.

10 Information from enzymes measurements in serum?
Presence of disease. Organs involved. Etiology /nature of disease: differential diagnosis. Extent of disease-more damaged cells-more leaked enzymes in blood.

11 Measurement of enzyme activity
Enzyme activity is expressed in International unit (IU): -It corresponds to the amount of enzymes that catalyzes the conversion of one micromole (mol) of substrate to product per minute.

12 What are the enzymes most used the diagnosis of certain diseases?

13 Plasma enzymes Functional **For example:- Isoenzymes Non functional
1-Lactate dehydrogenase(LDH) 2-Creatine kinase(CK) Isoenzymes 3-Alanine transaminase(ALT) 4-Aspartate transaminase(AST) 5-Alkaline phosphatase Acid phosphatase 7-Amylase & Lipase enzymes

14 Lactate dehydrogenase(LDH)
Lactic acid Pyruvic acid NAD NADH+H LDH is elevated in myocardial infarction, blood disorders. It is a tetramer protein and made of two types of subunits namely H = Heart, M = skeletal muscle. It exists as 5 different isoenzymes with various combinations of H and M subunits.

15 LDH1 ( H4) LDH2 (H3M1) LDH3 (H2M2) LDH4 (H1M3) LDH5 (M4) HHHH HHHM
Isoenzyme name Composition Present in Elevated in LDH1 ( H4) HHHH Heart, RBC myocardial infarction LDH2 (H3M1) HHHM LDH3 (H2M2) HHMM lungs and spleen leukemia LDH4 (H1M3) HMMM viral hepatitis LDH5 (M4) MMMM Skeletal muscle, Liver Skeletal muscle and liver diseases


17 Creatine kinase (CK) Creatine Creatine phosphate
ATP ADP (Phosphocreatine – serves as energy reserve during muscle contraction) Creatine kinase is a dimer made of 2 monomers. Skeletal muscle contains M subunit, Brain contains B subunits. Three different isoenzymes are formed.

18 CK-1 BB CK-2 MB CK-3 MM Isoenzyme name Composition Present in
Elevated in CK-1 BB Brain CNS diseases brain tumors CK-2 MB Heart Acute myocardial infarction CK-3 MM Skeletal muscle Skeletal muscle diseases


20 Alanine transaminase(ALT)
It is also called Serum glutamic pyruvic transaminase(SGPT). This enzyme is found predominantly in hepatocytes. It increases in liver & heart diseases. ALT is more specific for liver disease than AST.

21 Glutamic oxalacetic transminase(SGOT)
Aspartate transaminase(AST) Glutamic oxalacetic transminase(SGOT) *It is also called Serum glutamic oxaloacetic transaminase(SGOT) *It increases in liver & heart diseases.


23 **It is found in the bone , liver, intestine, placenta.
Alkaline phosphatase **It is found in the bone , liver, intestine, placenta. **Increases mainly in bone and liver diseases. Acid phosphatase **is found in the prostate, red blood cells, bone, liver, and pancreas. ** Mostly used to detect prostatic carcinoma. **Amylase and lipase enzymes increase in diseases of the pancreas as acute pancreatitis

24 Summary-Enzymes as diagnostic markers
Major diagnostic use Origin Enzyme Myocardial infarction Heart, liver, muscle, RBC Lactate dehydrogenase (LDH) Muscle disease Skeletal Muscle Heart Muscle Brain Creatine kinase (CK) Viral hepatitis Heart and Liver Alanine aminotransferase (ALT) Serum glutamate-pyruvate transaminase (SGPT) Liver and heart disease Aspartate aminotransferase (AST) Serum glutamate-oxaloacetate transaminase (SGOT) Liver and bone disease Hepatobiliary tree Bone, placenta Alkaline phosphatase (ALP) Prostate cancer Prostate, erythrocytes Acid phosphatase (ACP) Acute pancreatitis Pancreas, Salivary glands Amylase Pancreas Lipase

25 Thank you

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