Chain A ( T7 R8 R9 K10 V11 C12 Y13 Y14 Y15 D16 G17 D18 H39 N40 L42 L43 N44 Y45 G46 L47 Y48 R49 K50 M51 E52 I53 Y54 R55 P56 H57 V122 K123 Q128 T129 L320 T322 I389 P390 E391 E392 S393 G394 D395 E396 D399 D400 K403 I405 S406 I407 C408 S409 S410 D411 K412 R413 I414 A415 C416 E417 E418 E419 F420 S421 D422 S423 E424 E425 E426 G427 N433 S434 S435 )