Chains and heterogens:
PDB Chain Sequences:
>1pi4A (A:) apqqindivhrtitplieqqkipgmavaviyqgkpyyftwgyadiakkqpvtqqtlfelg svsktftgvlggdaiargeiklsdpttkywpeltakqwngitllhlatytagglplqvpd evksssdllrfyqnwqpawapgtqrlyanssiglfgalavkpsglsfeqamqtrvfqplk lnhtwinvppaeeknyawgyregkavhvspgaldaeaygvkstiedmarwvqsnlkpldi nektlqqgiqlaqsrywqtgdmyqglgwemldwpvnpdsiingsdakialaarpvkaitp ptpavraswvhktgatggfgsyvafipekelgivmlanknypnparvdaawqilnalq
>1pi4B (B:) apqqindivhrtitplieqqkipgmavaviyqgkpyyftwgyadiakkqpvtqqtlfelg svsktftgvlggdaiargeiklsdpttkywpeltakqwngitllhlatytagglplqvpd evksssdllrfyqnwqpawapgtqrlyanssiglfgalavkpsglsfeqamqtrvfqplk lnhtwinvppaeeknyawgyregkavhvspgaldaeaygvkstiedmarwvqsnlkpldi nektlqqgiqlaqsrywqtgdmyqglgwemldwpvnpdsiingsdakialaarpvkaitp ptpavraswvhktgatggfgsyvafipekelgivmlanknypnparvdaawqilnalq