The electrophoresis technique that use isoelectric focusing is

(a) AGE
(b) PFGE
(c) 2D PAGE
(d) SDS PAGE

Correct answer: (C) 2D PAGE

Explanation:

Isoelectric focusing (IEF) is a technique used in Two-Dimensional Gel Electrophoresis (2D-PAGE) as the first dimension to separate proteins based on their isoelectric point (pI).

Why 2D-PAGE Uses Isoelectric Focusing?

1. First Dimension: Isoelectric Focusing (IEF)

   • Proteins migrate in a pH gradient until they reach their pI (isoelectric point), where they have no net charge and stop moving.
   • This separates proteins based on charge.

2. Second Dimension: SDS-PAGE

   • After IEF, proteins are further separated using SDS-PAGE, which sorts them by molecular mass.

Thus, IEF is a key step in 2D-PAGE, making it the correct answer.

Why Not the Other Options?

• (A) AGE (Agarose Gel Electrophoresis) ❌

  • Used for DNA, RNA, or large proteins, but it does not involve isoelectric focusing.

• (B) PFGE (Pulsed-Field Gel Electrophoresis) ❌

  • A special type of gel electrophoresis for separating large DNA molecules, but it does not use IEF.

• (D) SDS-PAGE ❌

  • SDS-PAGE separates proteins by size only and does not involve charge-based separation like IEF.

Final Answer:

✅ (C) 2D PAGE