Similarly, when {TAIL ~ the pH} of the environment falls below the pH of the protein, the protein has {HEAD ~ a net positive charge} 
when
Similarly , when { TAIL ~ the pH } of the environment falls below the pH of the protein , the protein has { HEAD ~ a net positive charge }
OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD