Taking a cue from a previous demonstration of the transplantation of an active surface between a mesophilecellulase and a thermophile cellulase, we expanded the technique to attempt the transplantation of a whole protein’s surface. This time, the proteins used as ancestors (to derive a novel whole-surface-transplanted protein) were not enzymes but structural proteins : two beta-sheet-based crystallins from the human eye lens, known as betaB2 and gammaB. Using the pre-existing high level of structural homology between the N-terminal domains of betaB2 and gammaB, and the similar homology between the C-terminal domains of the two proteins, we used our (now patented) surface transplantation approach to replace the surface of gammaB with the surface of betaB2, creating a new protein in the process – which we called Gambeta. Gambeta shows an interesting combination of characteristics drawn from its two ancestors. To take one example, the temperature at which its structure starts melting is similar to that of betaB2, and much lower than that of gammaB. However, unlike betaB2 which does not unfold completely at the lower temperature, and also unlike gammaB which unfolds completely at the higher temperature, gambeta unfolds completely at the lower temperature. Insights into this, and many other interesting facets of such transplantation await your reading of this paper.

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