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Enzymes as DTs I
Enzymes as drug targets I
| Question | Answer |
|---|---|
| Define Enzymes. | Proteins that catalyse reactions by reducing activation energy. |
| Names the types of catalytic mechanisms. | Acid-Base catalysis, Covalent catalysis, and Metal ion catalysis. |
| Explain Acid-Base catalysis. | Enzyme donates/accepts H+ from substrates to speed up reaction. |
| Explain Covalent catalysis. | Enzymes form transient covalent bonds to substrate. |
| Explain Metal ion catalysis. | Ion stabilises or shields the charge during reaction. |
| Define Enzyme Cofactors. | Low molecular weight compounds that bind to an enzyme and participate in the reaction. |
| State the Michaelis-Menten equation. | v = ((Vmax[S])/[S]+Km)). |
| What is Km? | The concentration of substrates that gives 50% of the maximum velocity of the enzyme. |
| Define Enzyme Inhibitors. | Potential drugs which interfere with catalysis. |
| What are the two types of enzyme inhibitors? | Reversible and Irreversible. |
| Name types of reversible inhibitions. | Competitive, Uncompetitive, Mixed, and Non-competitive. |
| What happens in competitive inhibition? | The inhibitor competes with the substrate for the active site of the enzyme and so prevents the substrate from binding. |
| State the effects of competitive inhibition. | Km increases, Vmax is unaltered. |
| How can you overcome the effect of competitive inhibition? | By adding more substrates. |
| What happens in uncompetitive inhibition? | The inhibitor binds to the enzyme-substrate complex and affects its catalytic function - presumably through an allosteric mechaniam because substrate binding is unaffected. |
| State the effects of uncompetitive inhibition. | Km and Vmax decrease. |
| What happens in mixed inhibition? | The inhibitor binds to the free enzyme and the enzyme-substrate complex and affects its catalytic function - presumably through an allosteric mechanism . |
| State the effects of mixed inhibition. | Vmax decreases, Km is also altered (increase or decrease). |
| What happens in non-competitive inhibition (a form of mixed)? | A special situation of mixed inhibition when the inhibitor binds to the free enzyme and enzyme-substrate complex with equal affinities. |
| What happens in irreversible inhibition? | A drug binds irreversibly to the enzyme, and it effectively eliminates a fraction of the enzyme. |
| State the effects of irreversible inhibition. | Vmax decreases, Km is unaffected. |
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Smileyfeng
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