Chain A ( N30 S31 S32 V33 G34 K35 T36 S37 F38 L39 F40 R41 F47 T48 P49 A50 F51 V52 S53 T54 V55 K60 D77 T78 A79 G80 Q81 E82 R83 Y84 D103 N106 E108 N135 K136 S165 A166 K167 D168 )