The methods of biotechnology, such as directed microbiological synthesis, biochemical methods of breaking down complicated organic compounds (especially those using the biological catalysts — enzymes — and immuno-biological enzymes in particular), and the methods of fine organic synthesis have recently been very successfully applied to obtaining physiologically active substances (PAS’s). The substances that have been synthesized and biosynthesized include proteins (enzymes), polypeptides and amino acids, nucleic acids, nucleotides, nucleosides, polysaccharides, low-molecular-weight hydrocarbons, and a variety of others that have a physiological effect, such as antibiotics, regulators of various types, hormones, and vitamins. Both natural and synthesized PAS’s are at first complex mixtures of substances, and the initial solutions may contain tens, hundreds, or even thousands of components, many of which are closely related to the desired product in terms of their physico-chemical properties. If the products of a chemical synthesis are very specific (the intermediate and side products being only admixtures), then during a biosynthesis a multicomponent solution will be formed. The culture liquid obtained is a very complicated mixture from which we have to isolate only one, or a small number of, components. Natural products too are no less important and include primary extracts from animal and vegetable tissues and solutions that have been obtained at the first stage of separating out a natural PAS. In all these, the separation of an individual or very pure PAS is a complex problem that can be solved using modern and effective physico-chemical methods. This then is the subject area of physico-chemical biotechnology.
KeywordsPermeability Crystallization Hydrocarbon Polysaccharide Sedimentation
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