3i6n

Mode of Binding of the Tuberculosis Prodrug Isoniazid to Peroxidases: Crystal Structure of Bovine Lactoperoxidase with Isoniazid at 2.7 Resolution

spinqualitylabelsall models 3i6n, resolution 2.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3i6n is a 1 chain structure with sequence from Bos taurus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CA, HEM, IOD, ISZ, SCN, MAN, NAG NonStd Res: SEP Related: 3gc1 Activity: Peroxidase, with EC number 1.11.1.7 Resources: FirstGlance, OCA, RCSB, PDBsum Function [PERL_BOVIN] LPO is an antimicrobial agent. It is thought to help protect the udder from infection and promote growth in newborn calves. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Isoniazid (INH) is an anti-tuberculosis prodrug that is activated by mammalian lactoperoxidase and Mycobacterium tuberculosis catalase peroxidase (MtCP). We report here binding studies, an enzyme assay involving INH, and the crystal structure of the complex of bovine lactoperoxidase (LPO) with INH to illuminate binding properties and INH activation as well as the mode of diffusion and interactions together with a detailed structural and functional comparison with MtCP. The structure determination shows that isoniazid binds to LPO at the substrate binding site on the distal heme side. The substrate binding site is connected to the protein surface through a long hydrophobic channel. The acyl hydrazide moiety of isoniazid interacts with Phe(422) O, Gln(423) O(epsilon1), and Phe(254) O. In this arrangement, pyridinyl nitrogen forms a hydrogen bond with a water molecule, W-1, which in turn forms three hydrogen bonds with Fe(3+), His(109) N(epsilon2), and Gln(105) N(epsilon2). The remaining two sides of isoniazid form hydrophobic interactions with the atoms of heme pyrrole ring A, C(beta) and C(gamma) atoms of Glu(258), and C(gamma) and C(delta) atoms of Arg(255). The binding studies indicate that INH binds to LPO with a value of 0.9 x 10(-6) m for the dissociation constant. The nitro blue tetrazolium reduction assay shows that INH is activated by the reaction of LPO-H(2)O(2) with INH. This suggests that LPO can be used for INH activation. It also indicates that the conversion of INH into isonicotinoyl radical by LPO may be the cause of INH toxicity. Mode of binding of the tuberculosis prodrug isoniazid to heme peroxidases: binding studies and crystal structure of bovine lactoperoxidase with isoniazid at 2.7 A resolution.,Singh AK, Kumar RP, Pandey N, Singh N, Sinha M, Bhushan A, Kaur P, Sharma S, Singh TP J Biol Chem. 2010 Jan 8;285(2):1569-76. Epub 2009 Nov 11. PMID:19907057 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Lactoperoxidase

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