Welcome Guest Search | Active Topics |

Tag as favorite
Proteins
Options
Previous Topic Next Topic
Natasha_4902
#1 Posted : Thursday, August 06, 2020 5:15:54 AM
Rank: Advanced Member

Groups: Registered
Joined: 6/8/2020
Posts: 62

Thanks: 0 times
Was thanked: 0 time(s) in 0 post(s)
Hi,

For passage 4 of the bio and biochem section of AAMC full length 2, why does denaturing a protein make it weigh less? Isn't it the same amount of material just unfolded?

Thank you
Back to top
Report?
INSTR_Katerina_102
#2 Posted : Thursday, August 06, 2020 7:45:50 PM
Rank: Advanced Member

Groups: Registered
Joined: 6/24/2019
Posts: 250

Thanks: 0 times
Was thanked: 0 time(s) in 0 post(s)
Hi Natasha,

I don't have access to the AAMC exams so if you could give more information this would help.

However, what I can generally say is that significantly changing the conformation of or denaturing a protein/piece of DNA that is running on a gel will change how it runs on a gel without changing its mass.

I hope this helps!

Katt
Back to top
Report?
Natasha_4902
#3 Posted : Friday, August 07, 2020 6:13:24 AM
Rank: Advanced Member

Groups: Registered
Joined: 6/8/2020
Posts: 62

Thanks: 0 times
Was thanked: 0 time(s) in 0 post(s)
Hi Katt,

The protein travelled from the distance of a 200kda protein when it was in its native form to the distance of a 100kda protein when it was denatured.

Thank you
Back to top
Report?
INSTR_Katerina_102
#4 Posted : Saturday, August 08, 2020 2:32:54 AM
Rank: Advanced Member

Groups: Registered
Joined: 6/24/2019
Posts: 250

Thanks: 0 times
Was thanked: 0 time(s) in 0 post(s)
Hi Natasha,

Ok, that doesn't seem to line up with the slight differences one would expect from a change in conformation.

My guess based on the information given is that this protein exists as a 200 kDa homodimer, and when you denature it each of the monomers runs at 100 kDa.

Again, I'm not sure without access to the question, but I hope this helps!

Katt
Back to top
Report?
INSTR_Katerina_102
#5 Posted : Wednesday, August 12, 2020 9:09:23 PM
Rank: Advanced Member

Groups: Registered
Joined: 6/24/2019
Posts: 250

Thanks: 0 times
Was thanked: 0 time(s) in 0 post(s)
Hi Natasha,

Thanks for your email.

You are correct, normally when you denature a protein you should expect to see around the same mass because it is the same protein but unfolded.

However, when you first isolate a protein you might not be able to say for sure its quaternary structure - that is, it could be two different polypeptide chains linked together with intermolecular forces.

In this case, we can deduce because in:

1.Native we see one band at 200 kDa
2. Denatured conditions we see one band at 100 kDa

To me, the most likely explanation is that there are two homodimers linked together, and we couldn't see this under native because they moved as one unit.

This makes sense because the total mass is the same 100 + 100 = 200 kDa, and when you seperate the two chains from each other you would expect to see them run further due to their smaller mass.

Please let me know if this is still unclear,

Thanks,

Katt
Back to top
Report?
Users browsing this topic
Guest (7)
Tag as favorite
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.

Clean Slate theme by Jaben Cargman (Tiny Gecko)
Powered by YAF | YAF © 2003-2009, Yet Another Forum.NET
This page was generated in 0.105 seconds.