This document discusses methods for separating proteins, focusing on electrophoresis techniques. It explains that proteins can be separated based on their size, charge, and binding properties to study each protein's individual structure and function. Electrophoresis methods separate proteins in an electric field based on factors like their molecular mass and charge. SDS-PAGE is described as denaturing proteins with SDS to give each one a uniform negative charge proportional to its size. Isoelectric focusing separates proteins based on their isoelectric point by using a pH gradient gel. Two-dimensional electrophoresis combines these methods to separate thousands of proteins based on both their isoelectric point and size.