Bovine lactoferrin structure

Moore SA, Anderson BF, Groom CR et al (1997) Three-dimensional structure of diferric bovine lactoferrin at 2.8 A resolutirat. J Mol Biol 274(2) 222-236... 

Antonini G, Rossi P, Pitari G et al (2000) Role of glycan in bovine lactoferrin. In Shimakaki K, Tsuda H, Tomita M, Kuwata T, Perraudin JP (eds) Lactoferrin structure, frmetion and applications. Elsevier Science, Amsterdam, pp 3—16... 

The first crystallographic studies on transferrins date back more than 20 years (58), and crystals of various transferrins have since been reported. These include the diferric forms of rabbit (59) and human (60) serum transferrins, hen (61) and duck (62) ovotransferrins, human (63) and bovine (64) lactoferrins, and the apo- (iron free) forms of human lactoferrin (65) and duck ovotransferrin (62). In spite of all this activity, the crystals in many cases have proved difficult to handle, and the X-ray analyses quite challenging. A low-resolution analysis of rabbit serum transferrin in 1979 demonstrated the bilobal nature of the molecule (66), but it was not until 1987, with the publication of the structure of human lactoferrin (67), that full details of a transferrin... 

Lactoferrin has been isolated and identified from a wide variety of animal species. However, most of the studies on structure and iron-binding properties have involved either human or bovine proteins (2). Lactoferrin closely resembles transferrin in molecular weight of 75,000 to 90,000 and consists of a single polypeptide chain that binds two ferric ions. The pi of transferrin is 5.9 while that of lactoferrin is approximately 9.0 (8) and has an even higher association constant for iron-binding. Lactoferrin has the property of retaining its iron even in the presence of a relatively low-affir-nity iron chelator such as citrate below pH 4.0. Transferrin, on the other hand, looses its iron when the pH is lowered from 6 to 5 (7). There is extensive information in the literature concerning the physical properties of lactoferrin which will not be covered in this paper. 

In this section, a brief overview of the structural characteristics of the food proteins most widely used in studies on protein-protein complex formation is presented. Proteins presented below and in Table 1 are from milk [p-lactoglobulin (P-Lg), a-lactalbumin (a-La), bovine serum albumin (BSA), lactoferrin, caseins] or egg white (ovalbumin, lysozyme), even if proteins from other sources (including gelatin and soy and wheat proteins) are also used for self-assemblies and complex formation studies. The proteins presented are mainly monomers, but are able to self-assemble into oligomers or aggregates in some specific conditions. These conditions are also addressed. 

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