7ve3 | pdb_00007ve3

Structure of the complex of sheep lactoperoxidase with hypoiodite at 2.70 A resolution

spinqualitylabelsall models 7ve3, resolution 2.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 7ve3 is a 1 chain structure with sequence from Ovis aries. This structure supersedes the now removed PDB entry 3r5q. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.7Å Ligands: 61D, CA, HEM, IOD, NAG, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Lactoperoxidase (1.11.1.7, LPO) is a mammalian heme peroxidase found in the extracellular fluids of mammals including plasma, saliva, airway epithelial lining fluids, nasal lining fluid, milk, tears, gastric juices, and intestinal mucosa. To perform its innate immune action against invading microbes, LPO utilizes hydrogen peroxide (H2 O2 ) to convert thiocyanate (SCN(-) ) and iodide (I(-) ) ions into the oxidizing compounds hypothiocyanite (OSCN(-) ) and hypoiodite (IO(-) ). Previously determined structures of the complexes of LPO with SCN(-) , OSCN(-) , and I(-) show that SCN(-) and I(-) occupy appropriate positions in the distal heme cavity as substrates while OSCN(-) binds in the distal heme cavity as a product inhibitor. We report here the structure of the complex of LPO with IO(-) as the first structural evidence of the conversion of iodide into hypoiodite by LPO. To obtain this complex, a solution of LPO was first incubated with H2 O2 , then mixed with ammonium iodide solution and the complex crystallized by the addition of PEG-3350, 20% (wt/vol). These crystals were used for X-ray intensity data collection and structure analysis. The structure determination revealed the presence of four hypoiodite ions in the substrate binding channel of LPO. In addition to these, six other hypoiodite ions were observed at different exterior sites. We surmise that the presence of hypoiodite ions in the distal heme cavity blocks the substrate binding site and inhibits catalysis. This was confirmed by activity experiments with the colorimetric substrate, ABTS (2,2'-azino-bis(3-ethylbenzthiazoline-sulfonic acid)), in the presence of hypoiodite and iodide ions. Structural evidence of the oxidation of iodide ion into hyper-reactive hypoiodite ion by mammalian heme lactoperoxidase.,Singh PK, Ahmad N, Yamini S, Singh RP, Singh AK, Sharma P, Smith ML, Sharma S, Singh TP Protein Sci. 2021 Nov 11. doi: 10.1002/pro.4230. PMID:34761444 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Lactoperoxidase

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