Chain A ( C275 G276 R277 E279 W292 V293 H295 C296 N299 E301 E302 H304 Y787 D788 P789 G790 L791 K792 E814 F815 K816 C817 D819 A822 L823 S824 E826 T827 I828 G829 L865 Y867 G868 I879 E880 I881 V882 K883 D884 T955 T957 N959 )