Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
, 82 (23), 8144-8

Mechanism of Action of the Group A Streptococcal C5a Inactivator

Mechanism of Action of the Group A Streptococcal C5a Inactivator

D E Wexler et al. Proc Natl Acad Sci U S A.


Virulent group A streptococci have been found to express a cell-surface factor that has the capability of inactivating complement-derived chemotactic factors. To determine the mechanism of action of this factor, we examined the interaction of purified inactivator with pure C5a chemotaxin. Ligand-receptor binding studies demonstrated that streptococcal chemotactic factor inactivator (SCFI)-treated C5a expressed a greatly reduced ability to bind to receptors of polymorphonuclear leukocytes as compared with native C5a. The inactivation of C5a occurred by a nonstoichiometric and temperature-dependent process. NaDodSO4/PAGE analysis indicated that SCFI mediated a small decrease in the molecular weight of C5adesArg, and sequencing of the carboxyl terminus of inactivated C5a demonstrated that a six-residue peptide was lost. The release of discrete peptide fragments from denatured bovine serum albumin upon prolonged incubation with SCFI was indicative of endoprotease activity. Although denatured bovine serum albumin was inefficiently cleaved, native bovine serum albumin and other native proteins were highly resistant to SCFI proteolysis; this indicated that activity was specific in nature.

Similar articles

See all similar articles

Cited by 65 PubMed Central articles

See all "Cited by" articles


    1. J Clin Invest. 1974 Feb;53(2):591-9 - PubMed
    1. Adv Immunol. 1978;26:1-53 - PubMed
    1. Nature. 1970 Aug 15;227(5259):680-5 - PubMed
    1. J Clin Invest. 1970 Dec;49(12):2427-36 - PubMed
    1. J Immunol Methods. 1978;24(3-4):389-93 - PubMed

Publication types

MeSH terms

LinkOut - more resources