Chains and heterogens:
PDB Chain Sequences:
>1nas_ (-) adglgcavcvltgasrgfgralapqlarllspgsvmlvsarsesmlrqlkeelgaqqpdl kvvlaaadlgteagvqrllsavrelprpeglqrlllinnaatlgdvskgflnvndlaevn nywalnltsmlcltsgtlnafqdspglsktvvnisslcalqpykgwglycagkaardmly qvlaaeepsvrvlsyapgpldndmqqlaretskdpelrsklqklksdgalvdcgtsaqkl lgllqkdtfqsgahvdfyd