1jn2
From Proteopedia
Crystal Structure of meso-tetrasulphonatophenyl porphyrin complexed with Concanavalin A
Overview
The crystal structure of meso-tetrasulfonatophenylporphyrin complexed with concanavalin A (ConA) was determined at 1.9 A resolution. Comparison of this structure with that of ConA bound to methyl alpha-d-mannopyranoside provided direct structural evidence of molecular mimicry in the context of ligand receptor binding. The sulfonatophenyl group of meso-tetrasulfonatophenylporphyrin occupies the same binding site on ConA as that of methyl alpha-d-mannopyranoside, a natural ligand. A pair of stacked porphyrin molecules stabilizes the crystal structure by end-to-end cross-linking with ConA resulting in a network similar to that observed upon agglutination of cells by lectins. The porphyrin binds to ConA predominantly through hydrogen bonds and water-mediated interactions. The sandwiched water molecules in the complex play a cementing role, facilitating favorable binding of porphyrin. Seven of the eight hydrogen bonds observed between methyl alpha-d-mannopyranoside and ConA are mimicked by the sulfonatophenyl group of porphyrin after incorporating two water molecules. Thus, the similarity in chemical interactions was manifested in terms of functional mimicry despite the obvious structural dissimilarity between the sugar and the porphyrin.
About this Structure
1JN2 is a Single protein structure of sequence from Canavalia ensiformis. Full crystallographic information is available from OCA.
Reference
Functional equality in the absence of structural similarity: an added dimension to molecular mimicry., Goel M, Jain D, Kaur KJ, Kenoth R, Maiya BG, Swamy MJ, Salunke DM, J Biol Chem. 2001 Oct 19;276(42):39277-81. Epub 2001 Aug 14. PMID:11504727 Page seeded by OCA on Fri May 2 21:26:23 2008
