1f9b | pdb_00001f9b
MELANIN PROTEIN INTERACTION: X-RAY STRUCTURE OF THE COMPLEX OF MARE LACTOFERRIN WITH MELANIN MONOMERS
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Overview
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 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.
Reference
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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