2bjm: Difference between revisions

Induced fit is a predominant phenomenon in protein-ligand interactions, yet it is invariably attributed without establishing the existence, let, alone the structure, of the initial, low-affinity encounter complex. We, determined the crystal structure of the encounter complex on the pathway, of ligand binding by IgE antibody SPE7. We show that this complex is, formed by a wide range of ligands that initially bind with identical, affinity. Nonspecific ligands rapidly dissociate, whereupon the antibody, isomerizes to a nonbinding isomer. Specific ligand complexes, however, slowly isomerize to give a high-affinity complex. This isomerization, involves backbone and side-chain rearrangements of up to 14 A and the, formation of specific hydrogen bonds. The postbinding conformational, switch, combined with the prebinding isomerization to an energetically, favorable nonbinding isomer, results in a "kinetic discrimination", mechanism that mediates selective binding, by a factor of >10(3), between, highly related ligands that initially bind with the same affinity. This, model may apply to proteins that bind multiple ligands in a specific, manner or other proteins that, although capable of binding many ligands, are activated by only a few.

2BJM is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Rattus_rattus Rattus rattus] with ANF as [http://en.wikipedia.org/wiki/ligand ligand]. Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2BJM OCA].  

''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov  5 14:32:17 2007''