Unsaturated iron binding capacity UIBC

It has been further shown that a majority (approximately 60jt) of the extractable Qa (about 70 of the cellular gallium) from tumor and liver cells of the rat is associated with two macromolecular fractions of molar weight 1-1.2 x 105 Daltons and 4-5 X 10 Daltons (64) The 1-1.2 x 1o5 D band is found in both liver and tumor cells, whereas the 4-5 x 10 D band is found 

ACS Symposium Series American Chemical Society Washington, DC, 1980. 

Lactoferrin, with a molecular weight of 8.5-9.0 x 10 and a structure similar to transferrin (112) has been suggested as an alternative intracellular gallium-binding agent (113). 

Lactoferrin binds iron with a greater affinity than transferrin (114). and is found in tissues and secretions (especially milk) which localize galllum-67 (115.116.117.118.119). It was proposed that Ga labeled to transferrin and other plasma proteins Is transferred to cellular lactoferrin due to the latter s greater chelating ability (113-120). Such a transfer of gallium-67 has been demonstrated in vitro (121), and increased concentrations of the protein has been found in tumors (122.123.124). 

Perhaps the most exciting aspect of this proposed mechanism is the manner in which it correlates with recently-isolated lon-blndlng molecules called slderophores (129). The primary function of lactoferrin is to diminish the amount of extracellular free iron and thereby inhibit bacterial growth (130). Lactoferrin deposited by polymorphonuclear leukocytes is attached to the surface of monocytes and macrophages in inflammatory responses (130). Slderophores are synthesized by bacterial cells to sequester iron needed for growth, and 

---