Protein Protocols Protein Protocols

436 Dickinson and Fowler
biotinylated antibody can be used in place of the HRP-labeled antibody in Subheading
3.2., step 5. This is then detected using a streptavidin–HRP complex. This system may
result in more sensitive detection.
11. Drain off excess reagent by holding the membrane vertically and touching the edge of the
membrane against tissue paper. Gently place the membrane, protein side down onto the
Saran Wrap and lay a second piece on top, smoothing out any wrinkles. Alternatively, if
using a fluorescent scanner, a low fluorescence plastic document folder may be used.
4.3. Detection Using Film
12. Preflashing raises the film to the threshold of response so that the number of photons of
light hitting the film is more proportional to the number of silver grains converted.
13. Blots should be exposed to film immediately. The exact exposure time will have to be
determined empirically. If the exposure time required to view all standards is very short,
for example,