minimum radioactive probe size

I'm considering doing a lambda plaque hybridization with a very small
probe. The unique sequence I'm looking for is 43bp long. I'm lucky to
have that much really. We do our colony hybridizations exactly like we
would do a southern.

So has anyone done a hybridization (plaque or southern) with a tiny
probe like this? I imagine it might be hard to get a high enough
specific activity, but I think it's worth a shot.

Hi Ed,

when your probe is half size compared to a reference probe then you'll
need to double (at least) the specific activity of the probe in order
to get the same signal, assuming the probe binds in the same way. This
is achieved by increasing the specific activity in the labeling
reaction. As you normally will dilute the radioactive molecule with
cold compund, just.dilute less. The bigger problem might be to obtain
the right stringency for a small probe, so you'll need some fiddling
with conditions maybe. HTH

Wo

On Sep 26, 5:06 pm, Ed Siefker <[Only registered users see links. ]> wrote: