Chains and heterogens:
PDB Chain Sequences:
>2ptn_ (-) ivggytcgantvpyqvslnsgyhfcggslinsqwvvsaahcyksgiqvrlgedninvveg neqfisasksivhpsynsntlnndimliklksaaslnsrvasislptscasagtqclisg wgntkssgtsypdvlkclkapilsdsscksaypgqitsnmfcagyleggkdscqgdsggp vvcsgklqgivswgsgcaqknkpgvytkvcnyvswikqtiasn