Model studies on iron (III) ion affinity chromatography : II. Interaction of immobilized ferric ions with phosphorylated amino acids, peptides and proteins

• The chromatographic behaviour of phosphoamino acids, phosphopeptides and phosphoproteins and their non-phosphorylated counterparts was studied on Fe(III)-Chelating Sepharose and Fe(III)-Chelating Superose. The phosphorylated compounds, in contrast to their non-phosphorylated or dephosphorylated counterparts, adsorb to immobilized iron(III) ions at pH 5.5 and can be desorbed by an increase in pH. Phosphoamino acids were eluted at pH 6.5-6.7, whereas monophosphopeptides and phosphoprotamine eluted in the pH range 6.9-7.5. Molecules possessing clusters(s) of carboxylic groups are weakly retained (gamma-carboxyglutamic acid, Ala-Ser-Glu5) or bound (polyglutamic acid, beta-casein) to the immobilized iron(III) ions at pH 5.5. Dephosphorylated beta-casein was desorbed at pH 7.0, whereas for elution of native (non-dephosphorylated) beta-casein, phosphate buffer of pH 7.7 was required. The homopolymer of polyglutamic acid was desorbed in the pH range 6.0-6.3, whereas copolymers of glutamic acid and tyrosine require pH 7.0-7.3 or even phosphate buffer at pH 7.7 for elution.

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NATURVETENSKAP  -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)

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