( Eric Larson Bio-R...)Application-Specific PVDF Membranes: Immun-Blot PVDF Membrane for Western Blotting and Sequi-Blot PVDF Membrane for Protein Sequencing, Rev C

Eric Larson, Bio-Rad Laboratories, 2000 Alfred Nobel Drive, Hercules, CA 94547 USA

Introduction
PVDF membrane was originally introduced to protein use as an ideal medium for the harsh chemical environment of N-terminal, or Edman degradation, sequencing. Even though PVDF is very hydrophobic and requires a prewetting step in alcohol, its high protein binding capacity, target retention, and resistance to cracking have made it an appealing membrane for general laboratory techniques.

The two main applications for PVDF are N-terminal sequencing and immunoblotting, both of which benefit from the qualities of PVDF but rely on different features of the membrane. While sequencing work is concerned with retaining as much protein as possible, a western blot requires good signal retention with very low background. To provide the best membrane for each technique, Bio-Rad offers two grades of PVDF: Immun-Blot PVDF membrane for western blotting and Sequi-Blot PVDF membrane for protein sequencing.

Immun-Blot PVDF Membrane
The focus with a blotting membrane is on how well it delivers signal while resisting background and nonspecific binding. Immun-Blot PVDF membrane is ideal for chemiluminescent (Figure 1) and colorimetric (Figure 2) western blots because it very strongly retains target protein (140150 g protein/cm² membrane) but resists background that can obscure highsensitivity detection. Immun-Blot PVDF membrane retains proteins in any transfer format: tank blotting, semi-dry blotting, and dot blotting all deliver excellent results. For proteins that are difficult to transfer, up to 0.1% SDS can be added to the transfer buf
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