Chain A ( F21 A22 I23 P24 N25 H26 H38 M42 K72 A75 D76 D79 Y80 N202 ),  Chain B ( H38 G39 M42 D43 R44 T45 E46 R47 A49 R50 M53 A75 D76 L77 L78 D79 Y80 I81 K82 A83 L84 N85 R86 N87 S88 D89 R90 ),  Chain C ( P37 H38 G39 L40 I41 M42 D43 R44 T45 E46 R47 L48 A49 R50 D51 M53 K54 G57 K72 A75 D76 L77 L78 D79 Y80 I81 K82 A83 L84 N85 R86 N87 S88 D89 R90 S91 I92 ),  Chain D ( A22 H38 G39 L40 I41 M42 D43 K72 A75 D76 D79 Y190 N202 )