Editing Lactoferrin (section)

===Polymeric forms===
Both in blood plasma and in secretory fluids lactoferrin can exist in different polymeric forms ranging from [[monomer]]s to [[tetramer]]s. Lactoferrin tends to polymerize both ''in vitro'' and ''in vivo'', especially at high concentrations.<ref Name=Sousa /> Several authors found that the dominant form of lactoferrin in physiological conditions is a tetramer, with the monomer:tetramer ratio of 1:4 at the protein concentrations of 10<sup>−5</sup> M.<ref name="Bennett">{{Cite journal |vauthors=Bennett RM, Davis J |date=January 1982 |title=Lactoferrin interacts with deoxyribonucleic acid: a preferential reactivity with double-stranded DNA and dissociation of DNA-anti-DNA complexes |journal=The Journal of Laboratory and Clinical Medicine |volume=99 |issue=1 |pages=127–38 |pmid=6274982}}</ref><ref name="pmid6979357">{{Cite journal |vauthors=Bagby GC, Bennett RM |date=July 1982 |title=Feedback regulation of granulopoiesis: polymerization of lactoferrin abrogates its ability to inhibit CSA production |journal=Blood |volume=60 |issue=1 |pages=108–12 |doi=10.1182/blood.V60.1.108.108 |pmid=6979357 |doi-access=free}}</ref><ref name="pmid7762423">{{Cite book |title=Lactoferrin Structure and Function |vauthors=Mantel C, Miyazawa K, Broxmeyer HE |year=1994 |isbn=978-0-306-44734-1 |series=Advances in, Experimental Medicine and Biology |volume=357 |pages=121–32 |chapter=Physical Characteristics and Polymerization During Iron Saturation of Lactoferrin, A Myelopoietic Regulatory Molecule with Suppressor Activity |doi=10.1007/978-1-4615-2548-6_12 |pmid=7762423}}</ref>

It is suggested that the [[oligomer]] state of lactoferrin is determined by its concentration and that [[polymerization]] of lactoferrin is strongly affected by the presence of Ca<sup>2+</sup> ions. In particular, monomers were dominant at concentrations below 10<sup>−10</sup>−10<sup>−11</sup> M in the presence of Ca<sup>2+</sup>, but they converted into tetramers at lactoferrin concentrations above 10<sup>−9</sup>−10<sup>−10</sup> M.<ref name=Bennett /><ref name="Furmanski">{{Cite journal |vauthors=Furmanski P, Li ZP, Fortuna MB, Swamy CV, Das MR |date=August 1989 |title=Multiple molecular forms of human lactoferrin. Identification of a class of lactoferrins that possess ribonuclease activity and lack iron-binding capacity |journal=The Journal of Experimental Medicine |volume=170 |issue=2 |pages=415–29 |doi=10.1084/jem.170.2.415 |pmc=2189405 |pmid=2754391}}</ref> [[Titer]] of lactoferrin in the blood corresponds to this particular "transition concentration" and thus lactoferrin in the blood should be presented both as a monomer and tetramer. Many functional properties of lactoferrin depend on its oligomeric state. In particular, monomeric, but not tetrameric lactoferrin can strongly bind to DNA.