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