Chains and heterogens:
PDB Chain Sequences:
>1a21A (A:) tgraynltwkstnfktilewepksidhvytvqistrlenwkskcfltaetecdltdevvk dvgqtymarvlsyparngnttgfpeeppfrnspeftpyldtnlgqptiqsfeqvgtklnv tvqdartlvrrngtflslravfgkdlnytlyywrasstgkktattntneflidvdkgeny cfsvqavipsrkrkqrspesltect
>1a21A (A:) tgraynltwkstnfktilewepksidhvytvqistrlenwkskcfltaetecdltdevvk dvgqtymarvlsyparnttgfpeeppfrnspeftpyldtnlgqptiqsfeqvgtklnvtv qdartlvtflslravfgkdlnytlyywrkktattntneflidvdkgenycfsvqavipsr krkqrspesltect
>1a21B (B:) tgraynltwkstnfktilewepksidhvytvqistrlenwkskcfltaetecdltdevvk dvgqtymarvlsyparngnttgfpeeppfrnspeftpyldtnlgqptiqsfeqvgtklnv tvqdartlvrrngtflslravfgkdlnytlyywrasstgkktattntneflidvdkgeny cfsvqavipsrkrkqrspesltect
>1a21B (B:) tgraynltwkstnfktilewepksidhvytvqistrlenwkskcfltaetecdltdevvk dvgqtymarvlsypanttgfpeeppfrnspeftpyldtnlgqptiqsfeqvgtklnvtvq dartlvrrngtflslravfgkdlnytlyywrkktattntneflidvdkgenycfsvqavi psrkrkqrspesltect