Protein folding properties, dependence organism

As is well-known in practice, the protein folding properties and, hence the product quality is dependent on the cultivation conditions of the host organism. Thus, in order to guarantee products within narrow specification limits, the production process must be kept under tight control (4). An essential prerequisite is accurate monitoring of the process state and an optimization of the trajectories of the key process variables. Advanced control strategies require to predict the process behaviour at least over time horizons which are needed to influence the process so that the state variables will not escape from the acceptable intervals. Prediction, however, means that the process has to be modelled. 

Due to the variety of amino acids, the physical and chemical properties of a protein, eg, folding, stability, activity, and ultimately the biological functions, are all dependent on its structural composition. Generally, most proteins are unstable in polar solvents such as ethanol, but stable in non-polar solvents such as cyclohexane. As a group of special biopolymers that plays key roles in biosphere, the primary properties of proteins have to be evaluated either in artificially controlled environments (in vitro), or in the context of a cell or a whole organism (in vivo). 

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