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KMID : 0380019940090030279
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Korean Journal of Biotechnology and Bioengineering
1994 Volume.9 No. 3 p.279 ~ p.285
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Phsphoprotein Partitioning in Metal-Affinity Aqueous Two-Phase Systems and Prediction of Partitioning Behivior
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Chung Bong-Hyun
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Abstract
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A mathematical model has been derived and used to describe phosphoprotein partitioning in Fe(III) IDA-PEG/dextran two-phase systems. This model includes the inhibitory effects of hydrogen and hydroxyl ion concentrations on protein partitioning. For aqueous two-phase partitioning experiments, the Al and A2 subcomponents of ovalbumin carrying two and one surface phosphoryl group(s) were purified using an immobilized metal ion affinity chromatography (IMAC). The ratio of partition coefficients in the presence and absence of Fe(III)IDA-PEG, K/Ko, increased in the pH range of 3.0 to 5.0 due to deprotonation of the second oxygen of the phosphoryl group, and above pH 5.0 declined steeply hy the inhibitory binding of hydroxyl ions to the metal ion. This partitioning behavior was well-described by the mathematical model. The binding constants for formation of the complex between the phosphoryl group and the Fe(III)IDA-PEG were found to be 6.1 x 103 M-´ and 2.3 x 10" M-´ in the top and bottom phases, respectively. These values are 3-5 times those for interaction of Cu(II)IDA-PEG with a single surface-accessible histidine.
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