Help on Enzyme Catalysts

[h2o91]

Hey all, just had some difficulty understanding these statements.

Was wondering if I could get some help. Thanks.

True or False?

1) Enzymes exhibit high stereospecificity, even on prochiral substrates, for example,distinguishing between different hydrogens on the same carbon of NAD(P)H.

2) Enzymes can enhance the spontaneity of a reaction, i.e. convert a process ( A-->B )that is endergonic so that it is exergonic.

3) By optimizing the proximity and orientation of substrates and key catalytic residues in the active site, an enzyme can couple two half reactions, one highly exergonic, the other somewhat endergonic, to yield an overall thermodynamically favorable reaction.

4) Enzymes accelerate biological reactions by preferential binding to the ground state, as demonstrated by the development of catalytic antibodies.

5) As catalysts, enzymes are not consumed during the reaction process, but are able to turn over multiple times. This precludes covalent modification of the enzyme as part of the

catalytic process.

Any help would be appreciated. Thanks again.

[hypervalent_iodine]

What specifically don't you understand?

[h2o91]

So here's what I think, and I just wasn't 100% sure.

 

1) True, enzymes must be stereospecific

2) True, help lower activation energy

3) Again, true

4) Unsure

5) True

 

Again, just checking to see if I have the idea of enzymes right

Thanks

[Esrevinu]

Heres some things to keep in mind: Enzymes do not change the overall delta G of the reaction. They can lower the activation energy, either by stabilizing the transition state, or destabilizing the ground state.

 

Review what makes a reaction spontaneous, endergonic, and exergonic. Review the induced fit hypothesis and transition state analogs. Review enzyme mechanisms. Is covalent catalysis precluded? Look at chymotrypsin and decide. What about cofactors?

 

You have more wrong answers than right answers, but the way these questions are worded, are really testing your understanding