Immobilized metal-ion affinity partitioning of NAD(+)-dependent dehydrogenases in poly(ethylene glycol)-dextran two-phase systems

(Un)suitability of the use of pH buffers in biological, biochemical and environmental studies and their interaction with metal ions – a review

The present work reviews, discusses and update the metal complexation characteristics of thirty one buffers commercially available. Additionally, their impact on the biological systems is also presented and discussed.

Immobilized metal ion affinity chromatography: a review on its applications

After 35 years of development, immobilized metal ion affinity chromatography (IMAC) has evolved into a popular protein purification technique. This review starts with a discussion of its mechanism and advantages. It continues with its applications which include the purification of histidine-tagged proteins, natural metal-binding proteins, and antibodies. IMAC used in conjunction with mass spectroscopy for phosphoprotein fractionation and proteomics is also covered. Finally, this review addresses the developments, limitations, and considerations of IMAC in the biopharmaceutical industry.

Current and prospective applications of metal ion-protein binding

Since immobilized metal ion affinity chromatography (IMAC) was first introduced, several variants of this method and many other metal affinity-based techniques have been devised. IMAC quickly established itself as a highly reliable purification procedure, showing rapid expansion in the number of preparative and analytical applications while not remaining confined to protein separation. It was soon applied to protein refolding (matrix-assisted refolding), evaluation of protein folding status, protein surface topography studies and biosensor development. In this review, applications in protein processing are described of IMAC as well as other metal affinity-based technologies.

Comparative studies of recombinant human granulocyte-colony stimulating factor, its Ser-17 and (His)6-tagged forms interaction with metal ions by means of immobilized metal ion affinity partitioning. Effect of chelated nickel and mercuric ions on extraction and refolding of proteins from inclusion bodies

The chelation capability of the reactive dye Light Resistant Yellow 2KT towards metal ions, particularly mercury(II) was evaluated in the pH range 5.0-7.0, and it was shown that the dye-Hg(II) complex has a free site for the interaction with human recombinant granulocyte-colony stimulating factor (rhG-CSF) from Escherichia coli. Affinity partitioning of three rhG-CSF forms--native, rhG-CSF[Cys17--->Ser17] and (His)6-rhG-CSF was studied in aqueous two-phase systems, which contained metal ions--Cu(II), Ni(II) and Hg(II)--chelated by dye-poly(ethylene glycol) at pH 5.0 and 7.0, in the presence or absence of many selected agents. It was determined, that chelated Ni(II) ions exhibited stronger interaction with the hexahistidine-tagged protein form, while the extraction power of Cu(II) ions was found to be of comparable order of magnitude for all three protein forms at pH 7.0. A comparative study of rhG-CSF and both its forms partitioning in the presence of chelated Hg(II) ions at pH 7.0 and 5.0 revealed possible direct interaction between Hg(II) ions and unpaired Cys-17 of rhG-CSF. The partitioning of three rhG-CSF forms inclusion body extract was studied in the presence of chelated Ni(II) and Hg(II) ions thus explaining the efficiency of targeted proteins renaturation gained upon their inclusion body forms interactions with chelated metal ions.

Effects of specific binding reactions on the partitioning behavior of biomaterials

Affinity partitioning is a special branch of biomaterials separations using aqueous two-phase systems. It combines the capability of diverse biomolecules to partition in aqueous two-phase systems using the principle of biorecognition. As a result, the macromolecule exhibiting affinity for a certain ligand is transferred to that phase where the ligand is present. This chapter describes the present status of the theoretical background of this approach and the properties of various natural and artificial compounds which act as affinity ligands in liquid-liquid systems. The affinity partitioning of proteins (enzymes and plasma proteins), cell membranes, cells, and nucleic acids are described as typical examples. The results are discussed in terms of theoretical understanding and practical application.