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