Question
To determine the molecular weight of a purified protein you subject it to ESI mass spectrometry at pH = 2. The spectrum shows a series of peaks with two of the most prominent neighboring peaks having m/z ratios of 2137.4 and 2044.4 Give the Molecular weight in kDa in three significant figures. What is Z ? b. What is the molecular weight of protein in kDa
To determine the molecular weight of a purified protein you subject it to ESI mass spectrometry at pH = 2. The spectrum shows a series of peaks with two of the most prominent neighboring peaks having m/z ratios of 2137.4 and 2044.4 Give the Molecular weight in kDa in three significant figures. What is Z ? b. What is the molecular weight of protein in kDa


Answers
A protein has a molecular mass of $400 \mathrm{kDa}$ when measured by size-exclusion chromatography. When subjected to gel electrophoresis in the presence of sodium dodecyl sulfate (SDS), the protein gives three bands with molecular masses of $180,160,$ and 60 kDa. When electrophoresis is carried out in the presence of SDS and dithiothreitol, three bands are again formed, this time with molecular masses of $160,90,$ and $60 \mathrm{kDa} .$ Determine the sub-unit composition of the protein.
Okay, so we need to be able to find the weight of 682 amino acid residues. And this is a fairly a simple mathematical question. We just need to know what the average molecular weight of an amino acid is. So we know that the average molecular weight of an amino acid is 110 d a. Okay, And all we need to do for this is to find how much 682 amino acid residues way. All we gotta do is just multiply it by this number. So we're gonna multiply 110 times 682. So our final answer is going to be. If you just type that in on your calculator, you're going to get 75,020 and that's your final answer.
So we want to know what the molecular weight of 682 amino acids are. And before we can do that, we need to define what the average weight of a single amino acid is. So the average weight of a single amino acid is 110 d a. So now that we know this weakens all the problem. This problem is a fairly simple mathematical problem. All we need to do to get the answer that we're looking for is multiply 682 by 100. Pardon that by 110 and we'll get our final answer of 70 5020.
All right, so we want to know the weight of 682 amino acids. But first, before we solve this problem, we need to know how much one single amino acid ways. One single amino acid weighs 110 D a. Now, this problem is fairly simple. The way we find out, the weight of 682 amino acids is just multiplying. Ah, that number by 110. So all we have to dio is multiply 682 by 110. So our final answer will be 75,000 20. And there you go.