The villagers at a remote countryside have shown unusual longevity and there wer
ID: 849975 • Letter: T
Question
The villagers at a remote countryside have shown unusual longevity and there were rarely any cancer victims in the past decade. You and your team investigated the lifestyle of the residents, finding that a plant the villagers routinely included in their diet might be responsible for the longevity. You researched the literature and proposed that a protein the plant contained could be the main effective component that kept the villagers healthy. There is certainly great profit behind your finding if you can prove its effectiveness, so you decided to purify the protein and study it.
Which resin and buffer(s) will you choose? Please describe your purification strategy. You need to give detailed explanation on your choices to get the points. (3 pts)
(Hint: How does buffer pH affect the charge of the protein and the charge of resin
Explanation / Answer
1. we will use Anion exchange chromatography resin: diethylaminoethyl (DEAE)-cellulose and Tris Buffer having pH 8.
Since pI of our protein is 6, going for cation exchange chromatogaphy means, we will have to use a pH below 6 for which buffer is not available and another thing is going for pH like 5, 4 etc has inherent danger of the denaturation of protein. Hence we will go for anion exchange chromatography using buffer with pH 8.
Now effect of buffer pH8.:
on protein: as the pI of protein is 6, the buffer pHof 8.0 will make it lose proton and gain negative charge. so buffer pH will make protein gain negative charge.
On resin's functional group: As the pKa of resin's functional group is 11, it will be positively charged at the buffer pH 8.0.
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