I´m about to set up an off-target assay for a PLA2 enzyme and I´m wondering if i do always have to dispense my substrates in liposomes when doing a QRFRET assay
I don't have personal experience with this situation, but it seems to me that the assay could work using a non-ionic detergent such as Triton X-100 to dissolve the fluorescent lipid substrate, instead of using liposomes. A TX-100 concentration of at least 0.013% would be necessary. This is the critical micellar concentration. I have done a FRET assay using lipids dissolved in this detergent where the final TX-100 concentration was 0.04% (final).
Hi Gernot, a loooong time ago I was doing enzymatic assays of PLA2's isolated from snake venom.
I was using an automatic pH titrator and added PLA2's to a liposome mixture. The assay took a long time, but it gave me results.
I experimented with soluble PLA2 substrates, but never got good results.
Since PLA2's need to attach to phospholipid surfaces in order to do their job, I think that you have to use liposomes to measure their activity, unless someone has come up with a better way of measuring these guys.