“…Theo utcome extends,c onsiderably,anovel paradigm suggested in previous articles in this journal on footprinting membrane proteins [15] and on the use of fluorine chemistry in structural proteomics. [19,24,32] Our design steps include 1) reagent selection in terms of LogP,2 )reagent transfer to the membrane domain, 3) reagent photochemistry in the lipidlike medium to give free radicals (or other reactive species), and 4) tailored radical specificity/reactivity design to address the biochemical question at hand. Theresults suggest that this approach represents aproductive means to achieve adequatecoverage footprinting for membrane proteins,t or eport dynamic regions and residue location, and to accommodate expansion in many ways to include new reactive species, including free radicals from reagents modeled on the perfluoroalkyl system, carbenes, [15] and possibly carbocations.…”