Chain A ( E368 M371 N372 H394 T395 L396 H397 L398 Q399 L408 F411 R418 F419 V420 D421 L422 S423 N466 F467 M468 D469 R470 C471 K472 N473 K475 F476 T477 M478 D479 L480 S481 R482 C501 L502 S503 L504 S505 H506 V526 D528 L529 S530 H531 N532 A550 D552 L553 S554 Y555 N556 S580 S582 F603 )