The present invention relates to compositions, including pharmaceutical compositions that inhibit complement activation, and contain amino acid sequences X1-X2-X3-W-E-X4-X5-X6 and/or Z1-C1-Z2-P-Z3-Z4-C2-Z5 as described. The invention further relates to methods of inhibiting complement activation in vivo or ex vivo by administering a pharmaceutical composition as described herein.