Chain B ( M340 Y344 G345 S346 T398 T399 S400 P401 G402 S403 T404 Q405 K406 I407 L408 Y441 V443 T444 R445 Y446 E447 S462 N464 F479 M483 L514 A515 D516 S517 G518 Y519 G520 Q521 G522 E523 I524 L525 I526 Y535 V578 H583 G596 K597 S598 G599 T600 A601 E602 L603 K604 G611 R612 Q613 I614 G615 W616 F617 I618 I631 N632 V633 K634 D635 V636 Q637 D638 K639 M641 A642 N645 )