| 摘要 |
The present invention provides a novel approach to the production of restriction enzymes. More specifically, there is provided a novel method for cloning these enzymes, which comprises preparing DNA libraries from the DNA of an organism that synthesizes the restriction enzyme of interest, creating a suitable host containing a heterospecific methyltransferase gene able to protectively modify DNA from digestion by the restriction enzyme of interest, introducing the DNA libraries into the protectively modified host, and screening recombinant organisms to identify those carrying the desired restriction enzyme gene. The application of this method to the FspI and HaeIII restriction genes of Fischerella species and Haemophilus aegyptius, respectively, is described in detail, together with the resulting clones that form the basis of a new and useful process for purifying the FspI and HaeIII restriction enzymes.
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