Compare the Native & SDS PAGE gels to indicate if each sam...

Question

Compare the Native & SDS PAGE gels to indicate if each sample is a monomer, dimer, trimer or tetramer.

Comparison of Native-PAGE and SDS-PAGE gels showing protein samples for analysis.

a. Sample 1: ________________

b. Sample 2: ________________

c. Sample 3: ________________

d. Sample 4: ________________

Accepted Answer

So this practice problem wants us to compare the native and SDS PAGE gels to indicate if each sample is a monomer, dimer, trimer, or tetramer. And so, recall that a monomer only has 1 polypeptide chain, dimers have 2 polypeptide chains, trimers have 3 polypeptide chains, and tetramers have 4 polypeptide chains. And so down below on the left, we have our native page gel where the proteins are gonna retain their native conformations, and on the right, we have our SDS page gel, and we know that SDS denatures the proteins. And so looking at sample number 1 right here in this lane for the native page, notice that its native confirmation has a mass of a 180 kilodaltons. And so we can put a 180 over here. But looking at sample number 1 in the presence of SDS where it's denatured, notice that it shows up right around 60 ish kilodaltons, and so we can put 60 over here. And so what this is saying is that our native protein of a 180 kilodaltons, on the native page shell over here, over the 60 kilodaltons that's seen, when in the presence of SDS, will tell us how many subunits there are. And so a 180 divided by 60 is 3, so this tells us that there are 3 subunits in, sample number 1's protein. And so because there are 3 subunits, that tells us that it is a trimer, and so we can put trimer for part a. Now moving on to part b for sample 2, notice that with sample 2 here, the protein, under native page conditions shows up right around 75. And so we can put 75 over here, but with sample number 2 in the presence of SDS, it also shows up right around 75. And so what this means is that if we take 75 and divide it by 75, it comes out to 1. So this tells us that we only have 1 polypeptide chain and this must be a monomer. Now moving on to sample 3 here, what we'll see is that sample 3 and the presence of native page, notice that the native, confirmation shows up right around a mass of about 60. It's slightly below 63, so it's right around 60. And when we look at sample 3 in the presence of SDS, notice that it shows up right, right in between the 2535 markers, so that's right about 30. And so if we take the native, protein, mass, which is 60 kilodaltons, and divide it by the mass of the protein under SDS PAGE conditions, then, what we'll get is the number of subunits. So 60 divided by 30 comes out to 2, and so that tells us that we must have a dimer with 2 subunits. And so looking at our last sample, sample number 4, notice that sample number 4 in the presence of native page, it shows up right around a mass of about a 100 kilodaltons. So we can put a 100 right above this band. And looking at sample number 4, but in the presence of SDS where it gets denatured, notice that we only have one band showing up right at 25 kilodaltons. And so, essentially, what we can do is take the mass of our native protein, which is a 100 kilodaltons, and divide it by the mass of our subunits that are showing up at 25. And so what this tells us is a 100 divided by 25, that there are 4 subunits, and so 4 subunits would tell us that there's a tetramer. And so that would mean that the answer to part d here is tetramer. And so that answer to part d here is tetramer. And so that concludes this practice problem and I'll see you guys in our next video.

Struggling with Biochemistry?

Compare the Native & SDS PAGE gels to indicate if each sample is a monomer, dimer, trimer or tetramer.

a. Sample 1:
b. Sample 2:
c. Sample 3:
d. Sample 4:

Watch next

SDS-PAGE Strategies practice set

Struggling with Biochemistry?

Compare the Native & SDS PAGE gels to indicate if each sample is a monomer, dimer, trimer or tetramer.a. Sample 1: ________________b. Sample 2: ________________c. Sample 3: ________________d. Sample 4: ________________

Watch next

SDS-PAGE Strategies practice set

Compare the Native & SDS PAGE gels to indicate if each sample is a monomer, dimer, trimer or tetramer.

a. Sample 1:
b. Sample 2:
c. Sample 3:
d. Sample 4: