Protein folding pathway vitro

Recent reports on facilitation of protein folding by molecular chaperones 46-48) provide another possibility the difference between these two pathways could be a consequence of lack of certain cellular components in the in vitro reaction. It was observed that the products of gr< -bearing plasmid were able to rescue some temperature sensitive P22 tailspike mutants in Salmonella at the restrictive temperature (39 C), though very weakly 49), On the other hand, high yield of the native protein was also reported in the refolding (reconstitution) of the acid urea denatured tailspike polypeptide chains without the addition of cellular factors at low temperatures (10°C) (57). This in vitro result indicates that auxiliary factors inside the cell are not absolutely required for the folding of this protein, at least under these experimental conditions. However, this does not rule out that the cellular factors could play a role under in vivo conditions. 

In any case, the difference between the in vivo folding pathway and the in vitro thermal unfolding pathway indicates the importance of kinetic aspects in controlling the folding and unfolding of this protein. 

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