Production of proteins by fusion

It is not possible always to obtain recombinant proteins in the soluble form by using these methods. Those proteins that are obtained in insoluble form they can be solubilized by fusion process:

If we want to made the expression in simple form different fusion partners are obtained for this process. These fusion partners normally include tags that can be either linked to the protein or not. Many of these partners are used for purification process. The advantages of these fusion partners are that they protect the protein from degradation [181, 182] and also increase the solubility [183-185].

When the expression levels are high they are used in combination with those fusion partners that are poorly expressed [188]. Many tags exist and they have been studied extensively [189-191]. In these tangs the MBP is preferred as compared to GST in case of E.coli. It is also possible that by using these tags the levels of inclusion bodies may not be reduced.

Role:

As the recombinant proteins are attached with the tags they can be isolated by the use of proteases that are site specific. These enzymes are involved in cleavage of the sequences that are present in expression vectors. The selection of these enzymes depends on the sequence of amino acids. For this reason the tags with similar sequences are avoided.

Examples of these proteases include thrombin and Xa and both of these enzymes recognizes different amino acid sequences. These proteases are specific for the process of fusion.

Conclusion:

There are many expression systems that can be used to express recombinant proteins but E.coli is most commonly used for this purpose as it is the most attractive way for this purpose. In eukaryotic system there are no genetic modifications rather they are present in prokaryotic organisms and in eukaryotes these changes will be available in near future.

On industrial scale we can use E.coli for the production of many therapeutic proteins. There are many techniques through which we can produce those proteins that are biologically active. Most of the scientists prefer to produce proteins in soluble form. This is an art of produce many hormones, proteins, antibiotics and other products of biotechnological importance.

The vast knowledge is available for the production, separation and purification of proteins. In order to produce both prokaryotic and eukaryotic proteins the best host is E.coli. Those proteins that have high molecular weight cannot be efficiently expressed they can be expressed by using E.coli as a host.

More of the bacterial proteins can be expressed and less of the non bacterial proteins are expressed. It is the aim that in near future many of the proteins will be expressed by using different techniques that will be discovered in near future and many of the draw backs that are occurring in previous techniques can be overcome.