Dear Stephen,

I'd argue that photobleaching is a procedure which we barely understand. 
Most of the observations/rules are purely empirical and so far I have 
seen no comprehensive description of the procedure. Furthermore (as 
always) the details may be dependent also on the specific dye/fluorophore.
But back to your question: of course the reactive species created in a 
photobleaching experiment will harm also other proteins (or generally 
the cell). However, the overall assumption is that your 
bleaching/recovery experiment happens in a much faster time scale then 
the corresponding cytotoxic effects. Of course there are 
processes/methods like CALI (Chromophore Assisted Laser Inactivation) 
where people used the "immediate" effect of the putative reactive 
species (as far as I know also CALI is a poorly understood procedure).

Greetings    Gabor

-- 
Gabor Csucs 
Light Microscopy Centre, ETH Zurich
Schafmattstrasse 18, HPM F16 
CH-8093, Zurich, Switzerland

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