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.
The degrees in Science and Letters were added in the 19th century, and the degree in Philosophy was added in 1914. The higher bachelor's degree programme is generally a taught programme of one or two years for graduates.he DPhil is a research degree, modelled on the German and American PhD, which was introduced in 1914. Rather atypically, Oxford was the first university in the UK to accept this innovation. 1  Doctor of Clinical Psychology (DClinPsychol). 2  Doctor of Engineering (EngD).