Thrombin protein. Computer model of a molecule of the protein thrombin on a background of a 2-D gel used for separating proteins. Thrombin is a protein involved in the blood coagulation (clotting) process. A 2-D (two-dimensional) gel separates proteins by their mass and charge by the application of an electric field and a pH gradient respectively. These are aligned at right angles to each other. Individual dots are discrete protein fragments, which can be taken for further analysis. The study of the structure and function of proteins is called proteomics. Research into an organism's proteome (all the proteins comprising it) provides information on how it works.