Chain A ( S153 C154 M156 N157 A158 A159 L160 Q161 A162 L163 S164 N165 C166 T170 L188 K190 S191 Y192 Q193 K194 L195 V196 S197 E198 V199 W200 H201 K202 K203 R204 P205 S206 Y207 V208 V209 P210 T211 S212 L213 L630 S631 I633 C634 H643 Y644 I645 A646 Y647 C648 Q649 N650 V651 I652 N653 G654 Q655 W656 Y657 E658 F659 D660 D661 Q662 Y663 V664 T665 E666 F681 )