Chain A ( A698 F699 G700 K721 L723 P729 K730 A731 N732 K733 E734 I735 L736 D737 E738 A739 Y740 V741 M742 V810 H811 R812 D813 L814 N818 T830 D831 F832 G833 L834 A835 K836 Y845 E848 K851 P853 )