Nilotinib
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Pharmacokinetics
For Pharmacokinetic Data References, see: References |
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References
Better Known as: Tasigna
Mechanism of ActionChronic Myelogenous Leukemia (CML) results from a gene defect in a haematological stem cell, producing the kinase, BCR-Abl. Compared to the tightly regulated c-Abl kinase, BCR-Abl has a truncated auto-regulatory domain, leading to constitutive activation of its tyrosine kinase activity. The result of this nearly limitless activation is unregulated phosphorylation of downstream receptors leading to uncontrolled growth and survival of leukemic cells. Like many other receptor tyrosine kinases, BCR-Abl is at an equilibrium between two states, an active state and an auto-regulated inactive state. Nilotinib functions by binding in the ATP binding site and stabilizing the inactive conformation of BCR-Abl, in which the well known "DFG triad" is in the "out" conformation. A critically important residue, Thr 315, is known as the gatekeeper residue. In the inactive DFG out conformation, Thr 315 shifts to allow binding of Nilotinib. In other kinases like B-Raf, p38 & KDR, position 315 is occupied by a larger residue that is not conducive to Nilotinib binding, giving Nilotinib its high specificity.[2] A number of point mutations within BCR-Abl result in Imatinib resistance. There are 33 well known Imatinib resistance conferring mutations at positions like 244, 250, 252, 253, 315, 317, 351, and 396. Nilotinib has shown effectiveness with nearly all Imatinib resistant versions of BCR-Abl, with the exception of the T315I mutant. [3] In BCR-Abl, Nilotinib is bound by H-bonds to residues Met 318, Thr 315, Glu 286, Asp 381, along with hydrophobic interactions with residues His 361, Ile 293, Ala 380, Val 299, Met 290, Lys 271, & Ala 269, stabilizing the inhibited conformation of the kinase.[4][5] To see morphs of the movement of key structural elements Click: DFG Movement, P-Loop Movement, & the Activation Loop Movement.
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For Pharmacokinetic Data References, see: References |
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This page was last modified 13:15, 9 January 2024.