Chain A ( F38 L282 D283 V284 F285 Q286 Y296 W401 D429 I430 E431 K436 I466 D468 H470 C502 W503 Y509 W540 D542 M543 N544 E545 P546 S547 V548 F549 V554 R602 W615 D618 N619 D647 F651 F652 R674 H676 H678 L679 D680 )