Structure at 1.44 A resolution of an N-terminally truncated form of the rat serum complement C3d fragment.Zanotti, G., Bassetto, A., Battistutta, R., Folli, C., Arcidiaco, P., Stoppini, M., Berni, R.
(2000) Biochim Biophys Acta 1478: 232-238
- PubMed: 10825534
- DOI: https://doi.org/10.1016/s0167-4838(00)00040-6
- Primary Citation of Related Structures:
- PubMed Abstract:
Complement component C3 plays a key role in the complement-mediated immune defence, and occupies a central position within the complement cascade system. One of its degradation products, C3dg, was purified from rat serum and crystallised in two different crystal forms as N-terminally truncated fragment. Despite the truncation and the lack of a significant portion of the N-terminus as compared to C3d, the structure of the fragment is highly similar to that of recombinant human C3d (Nagar et al., Science 280 (1998) 1277-1281). Structural details of the reactive site have been obtained, suggesting a possible mode of thioester bond formation between Cys-1010 and Gln-1013 and thioester bond cleavage in the transacylation reaction involving His-1126. The truncation at the N-terminus of C3d leads to the exposure of a surface of the molecule that favours dimerisation, so that in both crystal forms, the fragment is present as a dimer, with monomers related by a two-fold axis.
Department of Organic Chemistry and Biopolymer Research Center, University of Padova, Italy. firstname.lastname@example.org