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