Proteins are the servants of life. They occur in all component parts of
living organisms and are staggering in their functional var- ty, despite
their chemical similarity. Even the simplest single-cell organism
contains a thousand different proteins, fulfilling a wide range of
life-supporting roles. Their production is controlled by the cell's
genetic machinery, and a malfunction of even one protein in the cell
will give rise to pathological symptoms. Additions to the total number
of known proteins are constantly being made on an increasing scale
through the discovery of mutant strains or their production by genetic
manipulation; this latter technology has become known as protein
engineering. The in vivo functioning of proteins depends critically on
the chemical structure of individual peptide chains, but also on the
detailed folding of the chains themselves and on their assembly into
larger supramolecular structures. The molecules and their fu- tional
assemblies possess a limited in vitro stability. Special methods are
required for their intact isolation from the source material and for
their analysis, both qualitatively and quantitatively. Proteins are also
increasingly used as "industrial components," e.g., in biosensors and
immobilized enzymes, because of their specificity, selectivity, and
sensitivity. This requires novel and refined proce- ing methods by which
the protein isolate can be converted into a form in which it can be
utilized.
