PMID: 12139449
Gibson AE, Arris CE, Bentley J, Boyle FT, Curtin NJ, Davies TG, Endicott JA, Golding BT, Grant S, Griffin RJ, Jewsbury P, Johnson LN, Mesguiche V, Newell DR, Noble ME, Tucker JA, Whitfield HJ
Probing the ATP ribose-binding domain of cyclin-dependent kinases 1 and 2 with O(6)-substituted guanine derivatives.
J Med Chem. 2002 Aug 1;45(16):3381-93.
O(6)-substituted guanines are adenosine 5'-triphosphate (ATP) competitive inhibitors of CDK1/cyclin B1 and CDK2/cyclin A, the O(6) substituent occupying the kinase ribose binding site. Fifty-eight O(6)-substituted guanines were prepared to probe the ribose pocket, and the structures of four representative compounds bound to monomeric CDK2 were determined by X-ray crystallography. Optimum binding occurs with a moderately sized aliphatic O(6) substituent that packs tightly against the hydrophobic patch presented by the glycine loop, centered on Val18, an interaction promoted by the conformational restraints imposed in a cyclohexylmethyl or cyclohexenylmethyl ring. Structure-based design generated (R)-(2-amino-9H-purin-6-yloxymethyl)pyrrolidin-2-one (56), which reproduces the reported hydrogen bonds formed between ATP and Asp86 and Gln131 but failed to improve inhibitory potency. Thus, the parent compound O(6)-cyclohexylmethylguanine (NU2058, 25) is the preferred starting point for exploring other areas of the kinase active site.