Affinity chromatography: The current status

New developments in protein isolation, purification, and characterization

The most significant advancements in techniques and methods for protein purification and analysis have been made in liquid chromatography and in electrophoresis. In the area of chromatography, adsorbents based on new affinity principles have been prepared. New packing materials have facilitated the rapid progress of high-performance techniques. A great many new techniques in the field of electrophoresis have emerged. On an analytical scale, electrophoretic methods in two dimensions or in capillaries are unsurpassed in resolution power. Development of techniques for protein transfer between different media is a prerequisite for a full exploitation of the new methods. Modern techniques for analysis of submicrogram quantities facilitate the separation, detection, and characterization of complex protein mixtures.

Affinity chromatography on immobilised nucleotides. The synthesis, specificity and applications of immobilised inosine 5'-monophosphate

The synthesis and characterisation of two IMP analogues, 8-(6-aminohexyl)-ionosine 5'-monophosphate, Ahx8IMP, and inosine 2',3'-O-[1-(6-aminohexyl)-levulinic acid amide]-acetyl 5'-monophosphate, (AhxLvn)2',3'IMP, is described. These analogues were attached to CNBr-activated agarose through the terminal amino group of the spacer molecule. The immobilised-IMP analogues displayed specificity for the inosine-nucleotide-dependent enzyme, IMP dehydrogenase (IMP:NAD+ oxidoreductase, EC 1.2.1.14) but not for the NAD+-dependent enzymes, L-alanine and L-acetate dehydrogenases. Escherichia coli IMP dehydrogenase could be eluted biospecifically from immobilised 8-substituted and ribose-substituted IMP adsorbents with IMP, XMP and GMP. Multiple peaks of enzyme activity in the elution profiles were interpreted in terms of aggregation of the enzyme. A protocol for the large-scale purification of E. coli IMP dehydrogenase is proposed. Homogeneous enzyme of specific activity 9.1 units/mg was obtained in 50% overall yield, representing 14 mg pure protein from a 20-1 culture of E. coli. The two IMP analogues were inactive as substrates in the IMP dehydrogenase reaction.