title: Tetrahydrofolates are greatly stabilized by binding to bovine milk folate-binding protein.
abstract: The dietary supply of folates and their measurement are both affected, potentially, by the instability of some folates. Labile folates appear to be stabilized by binding to folate-binding protein (FBP); this paper reports measurements of that stabilization. The degradation rates of the very labile tetrahydrofolate (H(4)folate) and moderately labile 5-methyltetrahydrofolate (5-CH(3)H(4)folate) were measured with the compounds free or bound to either soluble or immobilized bovine milk FBP. Complexation increased stability from 2- to > 1000-fold, depending on buffer and temperature conditions. H(4)folate at 4 degrees C and pH 6.7 appeared to be quite stable for > 100 d when bound to soluble FBP but had a half-life of < 1 h when free. Stabilization of milk folates may be a role of FBP and would improve the bioavailability of milk folate to newborns and other consumers.
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Queensland, St. Lucia, Queensland 4072, Australia.
authors.forename: Martina L
authors.initials: ML
authors.lastname: Jones
authors.forename: Peter F
authors.initials: PF
authors.lastname: Nixon
mesh_terms: D000818:Animals; D001682:Biological Availability; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002417:Cattle; D004355:Drug Stability; D058973:Folate Receptors, GPI-Anchored; D006207:Half-Life; D006863:Hydrogen-Ion Concentration; D008892:Milk / Q000737:chemistry* / Q000378:metabolism; D011956:Receptors, Cell Surface; D012995:Solubility; D013696:Temperature; D013763:Tetrahydrofolates / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D058973:Folate Receptors, GPI-Anchored; D011956:Receptors, Cell Surface; D013763:Tetrahydrofolates