Enzyme Inhibition(Competitive Inhibition)

Presented by: Swapnil Agarwal

Haren Patel, Vikshit Patel,

Alok Priyadarshi, Purnima Singh, Parth Bhatt, Lakshesh Jadav

Enzyme – Enzyme – Enzyme!!!!

What is it ????

Lets see……

Inhibitors

• Inhibitors are chemicals that reduce the rate of enzymic reactions

• The are usually specific and they work at low concentrations

• They block the enzyme but they do not usually destroy it

• Many drugs and poisons are inhibitors of enzymes in the nervous system

Enzyme InhibitorsEnzyme inhibitors are molecules that reducethe catalytic activity of enzymes. Reducing ofeffective enzymatic activity or completeblocking of enzyme may cause eithercomplete death of cell either modifications inthe pathways.

Appln: Drugs with cause complete inactivationof enzymes from essential pathways will causecell death and therefore such drugs can be usedas an antibiotics.

Example:

Classification:

• Basis of Reversibility:

–Reversible

– Irreservisible

• Basis of Competitiveness:

–Competitive

–Un Competitive

–Mixed

Basis of Reversibility:

• Reversible

• Reversible inhibitors bind to enzyme with only noncovalent interactions.

• Reversible inhibitors do not perform any chemicalchanges in enzyme or themselves and they are indynamic equilibrium with solution and can be removedfrom enzyme completely by reducing inhibitorconcentration in solution.

• Reversible inhibition is often used as a self-regulatedprocess in living cells, when the substrate or product ofsome enzymes acts as inhibitors for other enzymes.

• Irreversible

• Irreversible inhibitors binds to enzyme via covalent bonds and prevent enzyme from further performing of catalytic acts.

• It is necessary to understand, that irreversible inhibitors act on some selected group of enzymes, with no effect on other enzymes and proteins.

• According to this classification it is impossible to consider chemical or physical agents which inactivate all enzymes and protein as an inhibitors.

Basis of Reversibility:

Comparison:

Reversible Irreversible

Binds via non covalent interactions

Binds via covalentinteractions

Do not perform any chemical changes

Inhibitor binds to the substrate and prevent catalytic activity of enzymes.

Can be reversed, as there is no bonding between the inhibitor and substrate.

Irreversibility due to strong covalent bonding.

Basis of competitiveness:• Competitive Inhibition

–As the name implies, compete with the substrate for active site of the enzyme.

–Inhibitor is similar to natural substrates.

–Most commonly occurred process.

Competitive – Uncompetitive!!!

What is it ????

Lets see……

Inhibition Kinetics:

Rate Law:

rp = kcat (E.S)

Rearranging:

Total Enzyme:

Lineweaver-Burk Plot

Misc:

• Video• Allosteric Binding•Case Study

Questions..??