A protein assumes a neutral charge when {HEAD ~ the pH} of {TAIL ~ the environment} is equivalent to pI of the protein 
of
A protein assumes a neutral charge when { HEAD ~ the pH } of { TAIL ~ the environment } is equivalent to pI of the protein
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH