Inhibition of enzyme activity Various substances interfere with the operation of enzymes. These substances are called inhibitors . Significance of enzyme inhibitor study: Enzyme inhibition serves as a major control mechanism in biological system .
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Various substances interfere with the operation of enzymes. These substances are called inhibitors.
Significance of enzyme inhibitor study:
Thistype of inhibition occurs when the inhibitor closely resembles the substrate.
So, they compete for binding reversibly the active site.
Sulfa drugs inhibit folic acid synthesis by bacterial cells by competing with para amino benzoic acid which is essential for folic acid formation.
B- Folate analogues are used as antitumorse.g.Aminopterin & Methotrexate are analogues of folic acid and compete with it for dihydrofolatereductase needed for activation of folic acid into tetrahydro folic acid.
c) Malonate competes with succinate for the active site of succinatedehyrogenase enzyme.
Enzyme (a) is allosterically inhibited by the end product.
These bounded metabolites lead to conformational changes of the active site , causing an increase or decrease in activity.
e.gAcetyl CoA carboxylase is the regulatory enzyme in de novo synthesis of fatty acids, it is inhibited by fatty acids & stimulated by citrate.
Electrophoretic separation of serum LDH produces the following 5 isoforms:
( they perform no physiological function in blood ).
• Alanine aminotransferase (ALT): ↑↑↑ in acute viral hepatitis.
• Aspartate aminotransferase (AST): ↑↑chronic liver diseases as well as heart diseases.
• Alkaline phosphatase (ALP): increased in obstructive jaundice and bone disorders.
• Acid phosphatase (ACP): elevated in prostate cancer.
• Lipase (LPS): elevated in acute pancreatitis.