Chain A ( R686 L688 S689 D690 K691 L692 E693 I695 S696 K697 D698 L699 K700 D701 F702 S703 K704 S705 F706 D707 E708 A720 L727 T766 K769 S770 E773 N774 V776 K777 D778 V779 I780 I781 N782 Q783 K784 V785 T786 D787 K788 D814 L815 F818 S819 E821 Q822 L823 Q825 Q826 A827 Q828 K829 )