title: [Kinetics of dissociation of alpha-lactalbumin complexes with Ca2+ and Mg2+ ions].
abstract: Kinetics of dissociation of the complexes of bovine alpha-lactalbumin with Ca2+ and Mg2+ ions induced by mixing of the Ca2+- or Mg2+-loaded protein with the chelator of divalent cations EDTA has been studied by means of intrinsic fluorescence stopped flow method. Within the temperature region from 10 to approximately 37 degrees C the fluorescence kinetics curves for the Ca2+ removal are well fitted by one exponent with the rate constant ranging from 6.10(-3) to 1 s-1. Taking into account rather low rate of the fluorescence changes, one can assume that the limiting stage in this case is the dissociation of the single bound Ca2+ ion from the protein but not a conformational change which occurs after the Ca2+ dissociation. At temperatures above 37 degrees C the kinetics curves are best fitted by two exponents. The second exponent seems to be due to the denaturation of the apo-form of alpha-lactalbumin which takes place at these temperatures. The values of the dissociation rate constants of Mg2+ practically coincide with the values for Ca2+.
authors.forename: E A
authors.initials: EA
authors.lastname: Permiakov
authors.forename: A V
authors.initials: AV
authors.lastname: Ostrovskiĭ
authors.forename: L P
authors.initials: LP
authors.lastname: Kalinichenko
mesh_terms: D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D007700:Kinetics; D007768:Lactalbumin / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
chemical_list: D007768:Lactalbumin; D008274:Magnesium; D002118:Calcium
vernacular_title: Kinetika dissotsiatsii kompleksov alpha-laktal'bumina s ionami Ca2+ i Mg2+.