Ch Isoelectronic point
I feel your buffer at pH 8 is perfectly OK, since the PI is If pHi is the calculated pHi of your protein (is roughly the pHi of the . Related Publications. Relationship of muscular fatigue to pH and diprotonated Pi in humans: a (1) Department of Medicine, University of Pennsylvania, Philadelphia Pi, decimal expansion of, related to: A Pie, interlace digits of Pi and e, continued fraction of ePi; A mix digits of Pi, e and phi.
And because it's a happy proton acceptor, it is considered to be basic.
A Quick Guide to pH, pKa and pI
And we've drawn it out in its protonated form here after it's accepted an extra hydrogen, or proton. So now coming over to our carboxylic acid group, this group is a very willing proton donor.
And because it is a proton donor, we call this acidic.
And so we've drawn it out here after it's already donated its protons, so it has a negative charge. And now looking at the overall net charge of our amino acid, we can see that we have a positive charge here and a negative charge here, and so the overall charge is 0.
And we have a special name for when you have a molecule that has both a positive and a negative charge present. And that special word is called a "zwitterion," which comes from the German word for "hybrid.
In other words, an acidic solution. Well, we can think of acidic solutions as having a lot of excess protons around. So anything that can be protonated on our amino acid is going to be protonated, and so it's going to look like this. And now if you take a look at both of the groups on our amino acid, you can see that our amino group is still in its protonated form and carries a positive charge.
Index to OEIS: Section Ph
But now our carboxylic acid group has gained a proton and lost its negative charge. And now you can see that the overall net charge on this molecule is now positive 1. So now let's come over to the other end of the spectrum. Let's put our amino acid in a solution with a very high pH, say a pH of And so this is going to be really basic solution, and we can think of really basic solutions as having a lot of excess hydroxide anions around.
And so now, everything that can be deprotonated on our amino acid will be, so it's going to look like this. And if we look at our overall net charge of our amino acid now, our amino group has been deprotonated so now it is neutral, and the carboxylic acid group has been deprotonated and so it has a negative charge again.
And so it has an overall net charge of negative 1. So now we know that we have a range of forms that our amino acid can take. We have the positively charged version at low pHs all the way up to the negatively charged version at high pHs. Now back to our question about the isoelectric point.
Isoelectric point - Wikipedia
So the isoelectric point is the pH at which we go from the positive to the negative form. The GST proteins have evolved by gene duplication to perform a range of functional roles. GSTs also have non-catalytic roles, binding flavonoid natural products in the cytosol prior to their deposition in the vacuole. Recent studies have also implicated GSTs as components of ultraviolet-inducible cell signalling pathways and as potential regulators of apoptosis.
Glutathione S-transferase, Pi class (IPR) < InterPro < EMBL-EBI
The mammalian GSTs active in drug metabolism are now classified into the alpha, mu and pi classes. Additional classes of GSTs have been identified in animals that do not have major roles in drug metabolism; these include the sigma GSTs, which function as prostaglandin synthases. In cephalopods, however, sigma GSTs are lens S-crystallins, giving an indication of the functional diversity of these proteins.
The soluble glutathione transferases can be divided into the phi, tau, theta, zeta and lambda classes. The theta and zeta GSTs have counterparts in animals, whereas the other classes are plant-specific. In the case of phi and tau GSTs, only subunits from the same class will dimerise.
Within a class, however, the subunits can dimerise even if they are quite different in amino-acid sequence. An insect-specific delta class has also been described, and bacteria contain a prokaryote-specific beta class of GST. This class has received particular interest in relation to carcinogenesis.