Chain A ( G88 N89 E91 S92 D93 L94 Q95 S96 A98 V99 Q163 R249 T250 P251 Q252 I253 E254 Q255 A256 V257 G258 I259 V260 E433 T436 G437 M438 N439 D440 F441 L442 N443 V444 L445 S447 F494 Y498 )