1f9b
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MELANIN PROTEIN INTERACTION: X-RAY STRUCTURE OF THE COMPLEX OF MARE LACTOFERRIN WITH MELANIN MONOMERS
OverviewOverview
The concentration of melanin determines the intensity of colors of the, skin and hair of animals. Melanin pigments are tyrosine-based polymers, formed in melanocytes within specialized organelles called melanosomes. In, order to understand the mechanism of melanin polymerization, lactoferrin, a basic protein with a pI value of 9.0, has been used to produce melanin., Lactoferrin is a monomeric iron-binding protein with a molecular weight of, 80 kDa. The crystals of lactoferrin were soaked in a solution containing, dihydroxyphenylalanine (DOPA) and tyrosinase enzyme. These crystals were, used for X-ray intensity data collection. The intensity data were, collected to 2.7-A resolution to an overall completeness of 91% with an, R(sym) of 0.071. The crystals belong to orthorhombic space group, P2(1)2(1)2(1) with cell dimensions: a = 85.0 A, b = 99.8 A, c = 103.4 A., The structure was determined by molecular replacement method, using the, model of diferric mare lactoferrin, and refined to an R-factor 0.215, (R(free) = 0.287) for all the data to 2.7-A resolution. The final model, comprises 5,281 protein atoms from 689 amino acids, 2Fe(3+), 2CO(2-)(3), ions, 2 indole-5,6-quinone molecules (IQ), and 73 water molecules. Two IQ, molecules, one in each lobe, bind to lactoferrin. In the C-lobe, the IQ, binds in the iron-binding cleft, whereas in the N-lobe, it is located in, the side pocket between two alpha-helices, filled with solvent molecules, in the native iron-saturated mare lactoferrin. The IQ molecules interact, with protein molecule mainly through glutamic acid in both lobes, without, significant perturbation to the protein structure. The orientation of N-, and C-lobes in the present structure is similar to that observed in the, native iron-saturated protein. However, as a result of the binding of IQ, molecules, the orientations of the domains N1, N2 and C1, C2 in the two, cases differ slightly.
About this StructureAbout this Structure
1F9B is a Single protein structure of sequence from Equus caballus with FE, BCT and 3ID as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Lactoferrin-melanin interaction and its possible implications in melanin polymerization: crystal structure of the complex formed between mare lactoferrin and melanin monomers at 2.7-A resolution., Sharma AK, Kumar S, Sharma V, Nagpal A, Singh N, Tamboli I, Mani I, Raman G, Singh TP, Proteins. 2001 Nov 15;45(3):229-36. PMID:11599026
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