Protein function evolution insertion

Indications of the structural features which are essential for a particular type of activity may be obtained by comparing the structure of different proteins which perform the same or similar functions. The characteristics which have remained unchanged during the course of evolution can thus be established. Such studies confirm that, as with the haemoglobins, there is considerable tolerance for replacement, deletion or insertion of amino acids in certain regions of the protein molecule. 

The solid-state nanopores described in the previous section were developed for ease of modification and manipulation. However, nature has had the advantage of millions of years of evolution to perfect the size and function of proteinaceous nanochannels. Many nanopores exist in nature to allow selective passage of species across membranes found within eukaryotic cells. This review will briefly highlight both native nanopores from nature and protein nanopores that have been engineered for better application to sensor systems. Many of the unmodified protein nanopores that are utilized in nanotechnology today are transmembrane proteins that can be inserted easily into the support of a lipid bilayer or polymeric membrane. Some of the most commonly used native protein channels include a-hemolysin Mycobacterium smegmatis porin A (MspA),"° " outer membrane... 

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