Chains and heterogens:
PDB Chain Sequences:
>1s81A (A:) ivggytcaansipyqvslnsgshfcggslinsqwvvsaahcyksriqvrlgehnidvleg neqfinaakiithpnfngntldndimliklsspatlnsrvatvslprscaaagteclisg wgntkssgssypsllqclkapvlsdssckssypgqitgnmicvgfleggkdscqgdsggp vvcngqlqgivswgygcaqknkpgvytkvcnyvnwiqqtiaan