Page 293 - Applied Pharmacognosy

Types of Chemical markers

Behavior of proteins in a linear pH gradients
 Proteins are positively charged at pH below their

pI and negatively charged above their pI.
 A particular protein at pH value below its pI will

move toward the cathode during electrophoresis,
and will move toward the anode at pH value
above its pI. A protein at its pI will not move in
an electric field.
 When a protein is placed in a medium with a
linear pH gradient and subjected to an electric
field, it will initially move towards the electrode