Download MendeleyZinc/calcium- and cadmium/cadmium-substituted concanavalin A: interplay of metal binding, pH and molecular packing.
Bouckaert, J., Loris, R., Wyns, L.(2000) Acta Crystallogr D Biol Crystallogr 56: 1569-1576
- PubMed: 11092923
- DOI: https://doi.org/10.1107/s0907444900013342
- Primary Citation of Related Structures:
2ENR, 3ENR - PubMed Abstract:
The crystal structures of cadmium/cadmium and zinc/calcium concanavalin A (con A) at pH 5.0 and pH 6.15, respectively, were determined. The structure of cadmium/cadmium con A confirms that the secondary Cd(2+)-binding site S3 is empty at pH 5. The metal-binding sites S1 and S2 are only very slightly affected by the substitution with cadmium. On the other hand, S1 and S2 and most of the protein surface of zinc/calcium con A at pH 6.15 differ from other fully metal-bound and carbohydrate-free structures. Most of these structural differences at the protein surface are a result of the interplay between metal binding, protonation and crystal packing. This interplay is expressed by relative rotations and translations of the con A units in alternative crystal packings and participation in space-group conversions inside crystals in situ. The particular crystal packing of zinc/calcium con A creates a novel zinc-binding site S4. The Zn(2+) ion in S4 ligates two aspartates from one tetramer and a histidine from a symmetry-related tetramer.
Organizational Affiliation:
Laboratorium voor Ultrastructuur, Vlaams Interuniversitair Instituut voor Biotechnologie, Vrije Universiteit Brussel, Paardenstraat 65, B-1640 Sint-Genesius-Rode, Belgium. bouckaej@vub.ac.be
