Pharma gyan Pandit

Enzyme Inhibition:

1.     Chemicals other than substrates and products may interact with an enzyme influencing the reaction rate.

2.     Chemicals which bind to the active site but do not react will compete for formation of the ES complex and are known as competitive Inhibitors. Raising substrate concentrations will overcome this type of inhibition. 

3.     Chemicals which bind somewhere else than the active site but decrease the turnover constant for the enzyme are known as non-competitive inhibitors. Raising the substrate concentration will not overcome this type of inhibition.  

4.     Some agents simply denature or otherwise destroy the enzyme causing irreversible Inhibition. This type of inhibition is see often with chemicals which form covalent bonds with the enzyme.  CN^-, cyanide ion is an example of an irreversable inhibitor.  It binds to the cytochrome oxidase, a cofactored enzyme, and prevents it from allowing cell respiration.  If Na₂S_sO₃ is administered quickly the CN^- can be removed from the cofactored enzyme.  Most heavy metals, Pb, Hg denature enzymes in a similar manner.

Not all inhibitors are bad for you.  Penicillins act as an inhibitors for the transpeptidase enzyme which builds the protein portion of bacteria cell walls.