Libraries, kinase

As the nature of chemistry space depends upon the way in which compounds are represented, an absolute or universal chemistry space does not exist. Thus, any procedure that utilizes chemistry space may be subject to considerable uncertainty, and the results obtained in different chemistry spaces are likely to differ, sometimes in quite significant ways. This rather daunting circumstance has necessitated the use of practical, heuristic approaches that, while imperfect, have nevertheless performed in a reasonably satisfactory manner over the last three years. During this period about 120000 diverse, quality compounds have been added to our corporate compound collection. This does not include the many compounds obtained from combinatorially derived libraries and special target-directed (e.g., kinase) libraries. 

There are three major sources for a typical corporate compound collection project-specific compounds accumulated over a long period of time through medicinal chemistry efforts for various therapeutic projects, individual compounds from commercial sources, and compounds from combinatorial chemistry. In practice, compound collections are often divided into subsets, for example, the diverse subsets for general HTS and target-focused subsets (such as kinase libraries or GPCR libraries). For library design, diversity and similarity are generally built into the libraries of compounds to be synthesized and/or purchased (73). 

The fact that the aliosterically preferred conformation may be relatively rare in the library of conformations available to the receptor may have kinetic implications. Specifically, if the binding site for the modulator appears only when the preferred conformation is formed spontaneously, then complete conversion to alios terically modified receptor may require a relatively long period of equilibration. For example, the allosteric p38 MAP kinase inhibitor BIRB 796 binds to a conformation of MAP kinase requiring movement of a Phe residue by 10 angstroms (so-called out conformation). The association rate for this modulator is 8.5 x 105 M-1 s-1, 50 times slower than that required for other inhibitors (4.3 x 107 M 1 s-1). The result is that while other inhibitors reach equilibrium within 30 minutes, BIRB 376 requires 2 full hours of equilibration time [8],... 

Components of the JAK-STAT signaling pathway represent novel targets for pharmacological interventions [4]. Recently, a specific and orally active JAK3 antagonist was identified from screening of a chemical library for inhibitors of in vitro JAK3 kinase activity. The most effective compound, CP-690,550, was shown... 

Nserum L, Nprskov-Lauritsen L, Olesen PH. Scaffold hopping and optimization towards libraries of glycogen synthase kinase-3 inhibitors. Bioorg Med Chem Lett 2002 12 1525-8. 

Enzyme-adduct formation has also been successfully achieved with the Erbl and 2 (receptor tyrosine kinases from EGFR subfamily) [19, 20], suggesting that the tethered library-screening approach would also be amenable to protein kinases. 

McKenna, J. M., F. Halley, J. E. Souness, I. M. McLay, S. D. Pickett, A. J. Collis, K. Page, and I. Ahmed. An algorithm-directed two-component library synthesized via solid-phase methodology yielding potent and orally bioavailable p38 MAP kinase inhibitors, J. Med. Chem. 2002, 45, 2173-2184... 

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