SDS:
-Mobility out of the gel: increases mobility as SDS imparts negative charge to a protein and maintains it in a soluble state.
-Binding to membrane: reduces binding to nitrocellulose due to decreased hydrophobicity of the protein.
-Detection: may affect antigenicity of some proteins.
Alcohol in transfer buffer (i.e., methanol up to 20%):
-Mobility out of the gel: decreased; reduces pore size of gel.
-Binding to membrane: improves binding to nitrocellulose; removes SDS from proteins resulting in improved hydrophobic interactions.
Field strength (V/cm):
-Mobility out of the gel: field strength is the driving force of elution; if too low, sample is not completely transferred out of gel.
-Binding to membrane: if too high, sample passes through membrane without binding.
Transfer buffer:
-Mobility out of the gel: decreased if high conductivity and low resistance limit V/cm due to excessive heat generation; decreased if buffer pH is close to pI of native protein.
Membrane:
-Detection: PVDF and nylon require more stringent blocking conditions than nitrocellulose.
Gel:
-Mobility out of the gel: increases with thinner gels or larger gel pore size.
Find additional tips, troubleshooting help, and resources within our
Protein Electrophoresis and Western Blotting Support Center.