Reactions were terminated by rapid filtration and {TAIL ~ the radioactivity} bound to {HEAD ~ the filters} counted by liquid scintillation spectrophotometry 
Reactions were terminated by rapid filtration and { TAIL ~ the radioactivity } bound to { HEAD ~ the filters } counted by liquid scintillation spectrophotometry
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH