4R6N: Jacalin-carbohydrate Interactions. Distortion Of The Ligand As A Determinant Of Affinity

Jacalin is among the most thoroughly studied lectins. Its carbohydrate-binding site has also been well characterized. It has been postulated that the lower affinity of beta-galactosides for jacalin compared with alpha-galactosides is caused by steric interactions of the substituents in the former with the protein. This issue has been explored energetically and structurally using different appropriate carbohydrate complexes of jacalin. It turns out that the earlier postulation is not correct. The interactions of the substituent with the binding site remain essentially the same irrespective of the anomeric nature of the substitution. This is achieved through a distortion of the sugar ring in beta-galactosides. The difference in energy, and therefore in affinity, is caused by a distortion of the sugar ring in beta-galactosides. The elucidation of this unprecedented distortion of the ligand as a strategy for modulating affinity is of general interest. The crystal structures also provide a rationale for the relative affinities of the different carbohydrate ligands for jacalin.
PDB ID: 4R6NDownload
MMDB ID: 127109
PDB Deposition Date: 2014/8/26
Updated in MMDB: 2015/02
Experimental Method:
x-ray diffraction
Resolution: 1.67  Å
Source Organism:
Similar Structures:
Biological Unit for 4R6N: tetrameric; determined by author and by software (PISA)
Molecular Components in 4R6N
Label Count Molecule
Proteins (4 molecules)
Agglutinin Alpha Chain
Molecule annotation
Agglutinin Beta-3 Chain
Molecule annotation
Chemicals (14 molecules)
* Click molecule labels to explore molecular sequence information.

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