>1extB (B:) observed residues (from ATOM records)
mdsvcpqgkyihpqnnsicctkchkgtylyndcpgpgqdtdcrecesgsftasenhlrhc
lscskcrkemgqveissctvdrdtvcgcrknqyrhywsenlfqcfncslclngtvhlscq
ekqntvctchagfflrenecvscsnckkslectklclp