Electrophoretic mobility: which lipoprotein shows beta mobility?

• A. Chylomicrons
• B. VLDL
• C. LDL
• D. HDL

Answer: (C)

Electrophoretic mobility of lipoproteins reflects their surface composition and size. When lipoproteins are separated at alkaline pH, they fall into distinct regions: chylomicrons stay essentially at the origin because they are large and carry little net charge; VLDL sits in a pre-beta region between the origin and beta region; HDL moves fastest in the alpha region near the albumin; the particle that migrates with the beta region is LDL. This beta mobility arises because LDL has surface apolipoprotein B-100 and a charge/size profile that interacts with the beta-globulin region during electrophoresis. So, the lipoprotein showing beta mobility corresponds to LDL.