Description. Ammonium sulfate precipitation is one of the most commonly used methods for protein purification from a solution. In solution, proteins form hydrogen bonds with water molecules through their exposed polar and ionic groups.When high concentrations of small, highly charged ions such as ammonium sulfate are added, these groups compete with the proteins to bind to the water molecules.This removes the water molecules from the protein and decreases its solubility, resulting in precipitation.n solution, proteins form hydrogen bonds with water molecules through their exposed polar and ionic groups. When high concentrations of small, highly charged ions such as ammonium sulfate are added, these groups compete with the proteins to bind to the water molecules.
In the UK, a PhD stands for âDoctor of Philosophyâ, sometimes referred to as a âdoctorateâ. It is the highest level of degree that a student can achieve. At some institutions, including Oxford University, a Doctor of Philosophy is known as a DPhil.
In general, however, the PhD is the highest level of degree a student can achieve (with some exceptions, which are covered below). It usually follows a masterâs degree, although some institutions also allow students to progress straight to a PhD from their bachelorâs degree.ost institutions require that candidates hold an honors degree or a masterâs degree with high academic standing, along with a bachelorâs degree with at least upper second-class honors. In some cases, you can also apply for a PhD simply on the basis of your masterâs degree grades.