Q: I have a question about what solutions might be incompatible with the conjugated saporins. We have done an experiment where we injected a mixture of saporin conjugate (same batch we’ve used in previous studies here) and a cocktail of 5,7-dihydroxytryptamine and 6-hydroxydopamine (in 0.1% ascorbic acid) to try to deplete multiple neurotransmitters.
The way we did this was to prepare both solutions at double strength and to mix them immediately before loading the syringe and placing the injections. So the final solution has 0.05% ascorbate, 0.01 mg/ml saporin conjugate, and I think 6 µg/µl 5,7-DHT and 4 mg/ml 6-OHDA.
Anyway, we are doing the histology now and the cholinergic lesion didn’t work. I’m wondering whether the ascorbic acid might have either damaged the conjugation of the saporin to the antibody, or have inactivated the saporin molecule itself somehow.
A: You have well-described what the problem is. A reducing agent will inactivate the toxin, and of course, ascorbic acid is a potent reducing agent. Because of your experience, we have added a line in the data sheet to caution people. This is the first report of this happening in nearly fourteen years of business, so it just had not been an issue.
Related: Targeted Toxins