Of the collection of separation technologies known as 'affinity', affinity chromatography is by far the most widely used variant. Affinity chromatography is becoming increasingly important as the speed of the revolution taking place in biotechnology processing increases. The concept of an 'affinity' separation results from a naturally occurring phenomenon existing within all biological macromolecules. Each biological macromolecule contains a unique set of intermolecular binding forces, existing throughout its internal and external structure. When alignment occurs between a specific site of these forces in one molecule with the site of a set of forces existing in another (different) molecule, an interaction can take place between them. This recognition is highly specific to the pair of molecules involved. The interactive mechanism can be converted into a universal mutual binding system, where one of the binding pair is attached to an inert matrix, packed into a column and used exclusively to capture the other matching molecule. When used in this (affinity) mode, the technique is probably the simplest of all chromatographic methods. It is, however, restricted almost exclusively to the separation and purification of biological mac-romolecules, and is unsuitable for small molecules.

Affinity chromatography or bioselective adsorption chromatography was first used in 1910, but it was only in the 1960s that affinity chromatography as practised today was developed as a purification technique. By the late 1970s the emergence of recombinant DNA technology for the manufacture of protein pharmaceuticals provided a new impetus for this highly specific chromatographic method, implemented by the demand for ever-increasing product purity implicit in regulatory frameworks devised by (amongst others) the USA's Food and Drug Administration (FDA). Finally, the need to reduce the cost of drugs is under constant scrutiny by many Governments, particularly those with controlled health schemes funded by revenue raised by taxation. These mutually incompatible pressures indicate the need for more efficient separation systems; the affinity technique provides the promise of meeting all necessary requirements.

Separation and purification methods for biological macromolecules vary from the very simple to the esoteric. The type of technique adopted is basically a function of source, the fragility of the molecule and the purity required. Traditionally, high purity protein pharmaceuticals have used multistage processing, but this is very inefficient as measured by the well-documented fact that 50-80% of total production costs are incurred at the separation/purification stage. In contrast, the highly selective indigenous properties of the affinity method offer the alternative of very elegant single-step purification strategies. The inherent simplicity and universality of the method has already generated a wide range of separation technologies, mostly based upon immobilized naturally occurring proteinaceous ligands. By comparing the 'old' technologies of 'natural' ligands or multistage processing with the 'new', exemplified by synthetic designed ligands, the most recent advances in affinity processing can be described.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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