EK Biomolecules Question

[5words]

I believe there is a mistake on the figure, so just wanted to make sure i am not missing anything.. So here is the question

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A-Covalent
B Electrostatic
C- Van der Walls
D- MEtal Cofactor.

So i initially chose C, because H-bonding along with London forces are sometimes refereed together as Van der Wall forces. I came to this because of serine H-bond with the Carboxylic Oxygen same with the THr at 123. And the Tyr can also H-bond with the Amide Nitrogen although thats not plausible. But here is their explanatiion:

So question is, where is the Arginine in the above picture? i cant seem to find one? So, mistake or not? If it's not is there anything else on the pic that will make B the best answer choice?

@aldol16

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[5words]

Figure the msitake, Q stem says Arg 327 but the Figure says ASN (asparagine and not arginine) 327. So, def mistake right?

 

[aldol16]

I think the source of this whole confusion is the figure. The figure must be wrong - it should say Arg 327 instead of Asn 327. This is because the inhibitor clearly has a carboxylic acid that is negatively charged pointing right at residue 327. So residue 327 is most likely some positive charge that stabilizes the negative charge via electrostatics.

Although H-bonds are stabilizing, you would need several to stabilize a negative charge, as each H-bond only gives you about 3-5 kcals worth of stabilization. So usually to stabilize a negative charge, nature uses a positive charge, not a H-bond. Furthermore, while H-bonding could be included in the definition of van der Waals forces, van der Waals forces is usually used to refer to weaker forces such as London dispersion forces. We would usually refer to H-bonding separately and specifically because it's such a special case.

 

[5words]

I think the source of this whole confusion is the figure. The figure must be wrong - it should say Arg 327 instead of Asn 327. This is because the inhibitor clearly has a carboxylic acid that is negatively charged pointing right at residue 327. So residue 327 is most likely some positive charge that stabilizes the negative charge via electrostatics.

Although H-bonds are stabilizing, you would need several to stabilize a negative charge, as each H-bond only gives you about 3-5 kcals worth of stabilization. So usually to stabilize a negative charge, nature uses a positive charge, not a H-bond. Furthermore, while H-bonding could be included in the definition of van der Waals forces, van der Waals forces is usually used to refer to weaker forces such as London dispersion forces. We would usually refer to H-bonding separately and specifically because it's such a special case.

I see... And thanks..