Chain A ( H594 L595 G596 Q597 G598 T599 T601 N602 V603 V640 K642 V643 V673 M685 T687 V690 G693 P694 L695 D696 V697 R700 G733 N734 V735 C736 G737 R738 N739 I740 L741 L742 S758 D759 P760 G761 E774 R775 W778 T803 E806 I807 G811 )