Harmony of the Gel Electrophoresis

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My Electrophoresised Protein Sample to analyse protein characteristics • Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE) is a method of separating molecules of DNA, RNA and proteins based on the difference of their molecular weight. At the pH at which gel electrophoresis is carried out the SDS molecules are negatively charged and bind to proteins in a set ratio, approximately one molecule of SDS for every 2 amino acids. In this way, the detergent provides all proteins with a uniform charge to mass ratio, independently of their original charge. By binding to the proteins the detergent destroys their secondary, tertiary and/or quatenary structure denaturing them and turning them into negatively charged linear poly peptide chains. When subjected to an electric field in PAGE, the negatively charged poly peptide chains travel toward the anode with different mobility. Their mobility, or the distance traveled by molecules, is inversely proportional to the logarithm of their molecular weight. By comparing the relative ratio of the distance traveled by each protein to the length of the gel (Rf) one can make conclusions about the relative molecular weight of the proteins, where the length of the gel is determined by the distance traveled by a small molecule like a tracking dye. •Music: Steve Reich – Proverb
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