The 1 benzotriazolylcarbonate ester can then be reacted directly with a biologically active agent to form a biologically active polymer conjugate or reacted with {HEAD ~ an amino acid}, such as lysine, to form {TAIL ~ an amino acid derivative} 
The 1 benzotriazolylcarbonate ester can then be reacted directly with a biologically active agent to form a biologically active polymer conjugate or reacted with { HEAD ~ an amino acid } , such as lysine , to form { TAIL ~ an amino acid derivative }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL