In such a reagent, the liberated nucleic acids are protected from {HEAD ~ nuclease degradation} by {TAIL ~ the ionic detergent} 
by
In such a reagent , the liberated nucleic acids are protected from { HEAD ~ nuclease degradation } by { TAIL ~ the ionic detergent }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL