Title : Crystal structure of a recombinant alphaEC
domain from human
fibrinogen-420
Abstract :
- The crystal structure of a recombinant alphaEC domain from human fibrinogen-420 has been determined at a resolution of 2.1 A
- The protein, which corresponds to the carboxyl domain of the alphaE chain, was expressed in and purified from Pichia pastoris cells
- Felicitously, during crystallization an amino-terminal segment was removed, apparently by a contaminating protease , allowing the 201-residue remaining parent body to crystallize
- An x-ray structure was determined by molecular replacement
- The electron density was clearly defined, partly as a result of averaging made possible by there being eight molecules in the asymmetric unit related by noncrystallographic symmetry (P1 space group)
- Virtually all of an asparagine-linked sugar cluster asparagine-linked sugar cluster is present
- Comparison with structures of the beta- and gamma-chain carboxyl domains of human fibrinogen revealed that the binding cleft is essentially neutral and should not bind Gly-Pro-Arg or Gly-His-Arg peptides of the sort bound by those other domains
- Nonetheless, the cleft is clearly evident, and the possibility of binding a carbohydrate ligand like sialic acid has been considered