Electrophoretic techniques, such as sodium dodecyl sulfate-polyacrylamide gel electrophoresis SDS-PAGE and isoelectric focusing IEF , can be used to analyze the composition of a protein sample and determine the molecular weight and isoelectric point pI of the proteins present in the sample.1. SDS-PAGE for molecular weight determination:SDS-PAGE is a widely used electrophoretic technique for separating proteins based on their molecular weight. In this method, proteins are denatured and coated with negatively charged SDS molecules, which gives them a uniform charge-to-mass ratio. The proteins are then loaded onto a polyacrylamide gel, and an electric field is applied. The proteins move through the gel matrix towards the positive electrode, with smaller proteins moving faster than larger ones. After the electrophoresis is complete, the gel is stained to visualize the separated protein bands.To determine the molecular weight of the proteins in the sample, a standard protein ladder with known molecular weights is run alongside the sample. By comparing the migration distance of the sample proteins to that of the standard proteins, the molecular weight of the proteins in the sample can be estimated.2. Isoelectric focusing IEF for isoelectric point determination:IEF is an electrophoretic technique used to separate proteins based on their isoelectric point pI , which is the pH at which a protein has no net charge. In this method, a pH gradient is established across a gel or immobilized pH gradient IPG strip using ampholytes. The protein sample is then applied to the gel or strip, and an electric field is applied. Proteins will migrate through the pH gradient until they reach the pH corresponding to their pI, where they will have no net charge and stop moving.After the IEF is complete, the gel or strip can be stained to visualize the separated protein bands. The pI of the proteins in the sample can be determined by comparing their migration distance to that of standard proteins with known pI values or by using a calibration curve generated from the pH gradient.In summary, electrophoretic techniques like SDS-PAGE and IEF can be used to analyze the composition of a protein sample and determine the molecular weight and isoelectric point of the proteins present in the sample. These techniques are valuable tools in protein characterization, identification, and purification.