Chain A ( E450 M454 M457 I458 H461 D506 K507 T508 R509 E510 W511 A512 E513 L515 T516 H523 F524 I525 G526 D527 F528 L529 P530 P531 D532 E533 L534 E535 K536 F537 T540 Y552 S553 E554 Y555 K556 E557 F558 K594 T596 T597 T598 V599 D600 G601 A602 G603 I606 R608 A610 E611 L612 A621 F622 R623 K624 R625 M626 M627 L628 A629 Y630 R631 F632 R633 P634 N635 P636 N638 R642 P643 Y644 Y645 )