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219Gel electrophoresis Electrophoresis is the migration of charged particles in an electric field The buffers function to maintain the PH The proteins net charge is dependent on the PH of the solution they are placed in As the protein is placed into the buffer with specific PH the difference in the buffer PH relative to the isoelectric point of the protein determines the magnitude and type of charge on the protein acid pH pH pI positive charge migrates toward cathode basic pH pH pI negative charge migrates toward anode OR subtract the pH of the buffer from the pI of the protein if the resulting number is pos pos charge and vise versa eg pI 5 6 in PH 8 6 3 greater the difference between pI and PH the greater the charge typically use PH of 8 6 therefore proteins are anions negative charge and migrate toward the anode 1 What happens if the buffer solution you use has a low pH In the presence of a low acidic solution all the COOH groups present will exist as COOH groups and not as ions All the NH2 groups will have picked up hydrogen ions to form NH3 That means that all of the amino acids will carry a positive charge and all of them will move towards the negative electrode On the other hand if the buffer solution has a higher PH then all the COOH groups present will exist as COO ions All the NH2 groups will exist as simple NH2 groups not ions That means that all of the amino acids will carry a negative charge and all of them will move towards the positive electrode However due to mass and shape they will move in different rates 2 1 https quizlet com 19762196 electrophoresis flash cards 2 http www chemguideforcie co uk section112 learninga html