How could you make the zwitterion of aspartic acid more soluble in water?

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Welcome back, everybody. Let's take a look at the next problem which will increase the solubility of the Zwitterion of lysine and water. A buffering the water solution to a ph equal to the isoelectric point B, buffering the water solution to a ph less than the isoelectric point. See buffering the water solution to a ph greater than the isoelectric point or D both B and C. So let's think about this isoelectric point and what would increase the solubility of the Zwitterion. So let's think about what Z lysine looks like. It has an R group of H two N and then 1234 carbons. So go 1234 carbons. And then that last carbon is attached to our alpha carbon which has the bond to the NH two and the carboxyl group. And then, oh so when we look at this R group, we see that NH two at the very end, and we can predict that this is a basic R group. So let's think about the changes it goes through. We're calling that the isoelectric point is the point at which there's a net neutral electrical charge on our lying. So we'd start with the most protein form. So that means that both NH two groups should actually be NH three plus. So we will change that on here, NH three plus and H three plus. And our carboxylic acid group is proton, there's a hydrogen on that oxygen. So at this point, we have a net charge of positive two. Let's recall that our winter ion is one that has that net neutral charge. It's a dipolar electric charge where there's one positive and one negative that cancel each other out. So we have our lysine and it's completely protein form with a net charge of positive two. So we need to admission our ph slowly increasing such that we'll give up one of the hydrogens. So our most acidic group is the carboxylic acid. So that will become a negatively charged carboxylate group. So when we look at the molecule in this state, we have two positive charges of one negative. So the net charge is positive one. So now we remove one more hydrogen. That's right. The words increasing Ph at the top the little arrow going to the right. Well, now we'll give up the next most acidic hydrogen and that will be the hydrogen in the R group. So we'll now have a molecule where on the R group, it starts with H three H three, excuse me H two N with no charge. And then the NH three plus group is still there in the backbone of the amino acid as is our carboxylate group. So now in the backbone of the amino acid, we have one positive and one negative charge. And in the R group, our our group is in its neutral form. So at this point, we have a net charge of zero. And of course, we could take one more step where we removed that other hydrogen from the amine group in the backbone. And that would leave me with a net negative charge. So looking at our answer choices, let's think about what would increase the solubility well, being charged versus being neutral would increase the solubility. All right, being charged. But of course, the definition of the ele isoelectric point is that it's a point at which a molecule has a net neutral charge. So we would want to bring the water solution to a Ph less than or greater than the less isoelectric point. So less than would be choice B. So that would be correct. And choice C would says buffering the water solution to ph greater than the isoelectric point. Choice A says buffering the water solution to a ph equal to. But of course, the point equal to the is electric point is the one where the protein has no net charge. So choice A can't be correct. Now, we have joints A and B both correct. And we see that choice D is both B and C. So that's going to be our answer choice. Choice D both B and C for what increases the solubility of this winter ion in water? See you in the next video.

How could you make the zwitterion of aspartic acid more soluble in water?

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Key Concepts

Zwitterion

Hydrophilicity

pH and Solubility