changes were made which introduced either positively charged amino acids ( lys at positions 111 and 122 ) , negatively charged amino acids ( glu at positions 111 and 122 ) or oppositely charged amino acids ( lys at position 111 and glu at 122 ; asp at position 111 and arg at 122 ) at the borders of the h1-h2 extracellular domain .
C0002520
amino acids
C0061472
glu