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From Proteopedia
Crystal Structure of a Complex of Lactoferrin with a Lanthanide Ion (SM3+) at 3.4 Angstrom Resolution
Structural highlights
Function[TRFL_HORSE] Transferrins are iron binding transport proteins which can bind two Fe(3+) ions in association with the binding of an anion, usually bicarbonate. The lactotransferrin transferrin-like domain 1 functions as a serine protease of the peptidase S60 family that cuts arginine rich regions. This function contributes to the antimicrobial activity (By similarity). 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 PubMedLactoferrin is an important member of the transferrin family. A characteristic property of transferrins is their ability to bind very tightly (K(app) approximately/= 10(20)) but reversibly two Fe(3+) ions. The structural consequences of binding a metal other than Fe(3+) have been examined by crystallographic analysis at 3.4 A resolution of mare samarium-lactoferrin (Sm(2)Lf). The structure was refined to an R factor of 0.219 for 8776 reflections in the resolution range 17.0-3.4 A. The samarium geometry (distorted octahedral coordination) is similar in both lobes. However, the anion interactions are quite different in the two lobes. In the N lobe, the anion is able to form only two hydrogen bonds instead of the four observed in the C lobe of Sm(2)Lf and the six observed in Fe(2)Lf. This is because Arg121, Thr117 and Gly124 have moved away from the anion as a consequence of the binding of the Sm(3+) ion. The protein ligands in the binding cleft of Sm(2)Lf show large displacements, but the overall protein structure remains the same. The binding of Sm(3+) by lactoferrin shows that the protein is capable of sequestering ions of different sizes and charges, though with reduced affinity. This conclusion should be true of other transferrins also. Lactoferrin-metal interactions: first crystal structure of a complex of lactoferrin with a lanthanide ion (Sm3+) at 3.4 A resolution.,Sharma AK, Singh TP Acta Crystallogr D Biol Crystallogr. 1999 Nov;55(Pt 11):1799-804. PMID:10531475[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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