Stopped-flow kinetic studies of the interaction of bovine folate binding protein (FBP) and folate.
The kinetics of the interaction of bovine folate binding protein and folate at pH 7.4 and 5.0 were followed by measuring the changes of the intrinsic protein fluorescence intensity using the stopped-flow technique, which enables the study of reactions from the millisecond time-range. Our results immediately reject a simple one-step binding model, which requires a linear dependence of the observed rate constant on the concentration of the ligand. Thus, we are able to conclude that at pH 5.0 the interaction occurs in two steps and at pH 7.4 in three steps. Changes of fluorescence spectra at equilibrium were used to estimate the overall binding constants. Comparative studies on the binding of folate to human albumin are also reported.
Christensen
Ulla
U
Department of Chemistry, University of Copenhagen, Universitetsparken 5, Copenhagen, DK-2100, Denmark. Ulla@fk.ki.ku.dk
Holm
Jan
J
Hansen
Steen Ingemann
SI
D000465:Algorithms; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D002417:Cattle; D058973:Folate Receptors, GPI-Anchored; D005492:Folic Acid / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000378:metabolism; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism; D013050:Spectrometry, Fluorescence
D002352:Carrier Proteins; D058973:Folate Receptors, GPI-Anchored; D011956:Receptors, Cell Surface; D012709:Serum Albumin; D005492:Folic Acid