There is a hypothesis that the stability of a protein shows a strong correlation with its susceptibility to proteolytic degradation, with greater structural stability being associated with higher resistance to proteolytic degradation. In this paper, we use this hypothesis as the basis for developing a method for the purification of hyperthermophile-derived proteins cloned and expressed in Escherichia coli. Basically, we show that if the non-specific protease, subtilisin, is used on an E. coli lysate containing an overexpressed hyperthermophile protein like PyrococcusfuriosusTIM, the protease destroys all E.coli proteins without discernibly acting upon the population of overexpressed P. furiosusTIM (which is immune to the action of the protease, owing to its hyperthermostable structure being correlated with high stability to proteolytic degradation). The only other protein which survives the treatment and remains visible in trace amounts in the E.coli protein OmpF, which is an outer membrane protein. This could be a very efficient way of purifying any hyperthermophile protein expressed in E. coli, especially if combined with heat treatment.

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