Format

Send to

Choose Destination
See comment in PubMed Commons below
J Am Chem Soc. 2003 Dec 17;125(50):15280-1.

Potent small-molecule binding to a dynamic hot spot on IL-2.

Author information

  • 1Sunesis Pharmaceuticals, Inc., 341 Oyster Point Boulevard, South San Francisco, CA 94080, USA.

Abstract

The complexes between IL-2 and two similar small molecules, one a lead compound and the other a potent, affinity-optimized compound, were determined by X-ray crystallography. The lead compound (IC50 = 6 muM) bound to a hot spot on IL-2 in a groove that is not apparent in either the unliganded protein or a complex between IL-2 and a weakly bound drug fragment. The affinity-optimized compound (IC50 = 0.06 muM), which has an added aromatic acid fragment, bound in the same groove as the lead compound. In addition, a novel binding site was formed for the aromatic acid which is unseen in the complex with the lead compound. Thus, the hot spot on IL-2 is highly dynamic, with the protein changing form at multiple sites to maximize packing for each compound. Binding-site rigidity is often thought to play a role in high-affinity interactions. However, in this case, specific contacts between the small molecule and the protein are made despite the adaptivity of the hot spot. Given the change in morphology that was observed in IL-2, it is unlikely that a potent inhibitor could have been found by rational design. Therefore, fragment assembly methods offer the stochastic advantage of finding fragments in flexible protein regions where structural changes are unpredictable.

PMID:
14664558
DOI:
10.1021/ja0382617
[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for American Chemical Society
    Loading ...
    Support Center