Recombinant fragments of Factor C are disclosed. These proteins and peptides show great
potency in recognizing, binding to, neutralizing and removing endotoxin. These molecules can thus be used for anti-microbial, anti-endotoxin, and anti-
sepsis therapy. SSCrFCES is a 38 kDa
protein representing the LPS-
binding domain of Factor C. The ability of SSCrFCES to bind
lipid A was analyzed using an ELISA-based
assay as well as
surface plasmon resonance.
Surface plasmon resonance similarly carried out for SSCrFC-sushi-1,2,3-GFP, SSCrFC-sushi-1GFP, and SSCrFC-sushi-3GFP confirmed their superior affinity for endotoxin. The 50% endotoxin-neutralizing concentration of SSCrFCES against 200 EU of endotoxin is 0.069 μM, suggesting that SSCrFCES is an effective inhibitor of LAL
coagulation cascade. Although partially attenuated by human serum, as low as 1 μM of SSCrFCES inhibits the LPS-induced
secretion of hTNF-α and hIL-8 by THP-1 and human pheripheral blood mononuclear cells with a
potency more superior than
polymyxin B. SSCrFCES is non-cytotoxic, with a
clearance rate of 4.7 ml / minute. The LD90 of SSCrFCES for LPS
lethality in mice is achieved at 2 μM. These results demonstrate the endotoxin-neutralizing capability of SSCrFCES
in vitro and
in vivo, as well as its potential for use in the treatment of endotoxin-induced
septic shock. Also embodied in this application is the use of the sushi peptides and their
mutant derivatives as potent antimicrobials.