as was found in murine c5 , the corresponding thiol ester region of human c5 contained several conserved amino acids , but the critical cysteine and glutamine residues which give rise to the intramolecular thiol ester bond in c3 , c4 , and alpha 2-macroglobulin were absent in c5 , having been replaced by serine and alanine , respectively .
C0002520
amino acids
C0001898
alanine