title: Contrasting synergistic anion effects in vanadium(V) binding to nicatransferrin versus human serum transferrin.
abstract: Some ascidians sequester vanadium and other metal ions that are bound and transported in higher organisms by transferrin. The ascidian Ciona intestinalis has a monolobal transferrin (nicatransferrin) in its plasma. The binding of vanadium(V) to nicatransferrin was investigated by using isothermal titration calorimetry and UV-vis spectroscopy, in the presence and absence of NaHCO(3), and was compared with human serum transferrin. Nicatransferrin and serum transferrin bind V(V) with similar strengths [K = (2.0 +/- 0.6) x 10(5) M(-1) for nicatransferrin]; however, nicatransferrin requires a synergistic anion for V(V) binding, whereas serum transferrin does not. Spectroscopy supports a different kind of coordination site.
authors.affiliation: Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, USA.
authors.forename: Jean P
authors.initials: JP
authors.lastname: Gaffney
authors.forename: Ann M
authors.initials: AM
authors.lastname: Valentine
mesh_terms: D000818:Animals; D002938:Ciona intestinalis / Q000737:chemistry / Q000378:metabolism; D004357:Drug Synergism; D006801:Humans; D011485:Protein Binding; D021381:Protein Transport; D017693:Sodium Bicarbonate / Q000737:chemistry / Q000378:metabolism; D013816:Thermodynamics; D014168:Transferrin / Q000737:chemistry* / Q000378:metabolism*; D014638:Vanadates / Q000737:chemistry / Q000378:metabolism; D014639:Vanadium / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D014168:Transferrin; D014639:Vanadium; D014638:Vanadates; D017693:Sodium Bicarbonate; C101036:ammonium metavanadate