{HEAD ~ Amino sulfhydryl cross} linking {TAIL ~ reagents} that are cleavable under mildly acidic conditions are disclosed 
linking
{ HEAD ~ Amino sulfhydryl cross } linking { TAIL ~ reagents } that are cleavable under mildly acidic conditions are disclosed
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH