The question is whether there is a red fluorogenic substrate for
beta-galactosidase activity monitoring. Yes, there is, but there seems to
be a lot of trouble with the resorufin based material. If you have access
to UV excitation I would rather recommend a chloromethylcoumarin-based
substrate. This one is available from Molecular Probes, Inc. (Tel: (541)
465-8300 / FAX: (541) 344-6504) under catalog number D-2921. Disclaimer:
I have not tried it myself.
Good luck !
Martin Poot
martin@probes.mhs.compuserve.com