Page 292 - Applied Pharmacognosy

Types of Chemical markers

Isoelectric focusing

 Isoelectric focusing (IEF) is an electrophoretic
method in which proteins are separated on
the basis of their isoelectric points (pI).

 Proteins carry positive, negative, or zero net
electric charge, depending on the pH of their
surroundings.
 Proteins show considerable variation in pI,
but pI values fall in the range pH 3-12 with a
great many between pH 4-7.