Objective
The secretory nuclease from S. Marcesens is a unique endonuclease inasmuch as it cleaves both DNA and RNA in single stranded as well as in double stranded form with very high specific activity. As a secreted enzyme it is very stable, both with respect to thermal and chemical denaturation. It is an enzyme of considerable commercial interest as it can be effectively used to remove nucleic acids from pharmaceutical preparations, in particular from recombinant sources.
This project will study in detail the enzymology of this enzyme, which includes a characterisation of the active site of this enzyme by a mutational analysis and the description of the mechanism of cleavage. It will also investigate whether this enzyme can be immobilised on solid support, which would be interesting for two reasons: an immobilised nuclease could be very elegantly used to remove nucleic acids from recombinant protein preparations; and an immobilised nuclease when integrated in a biosensor could be used to detect minute amounts of nucleic acids as every phosphodiester bond cleaved liberates a proton.
It is likely that efficient immobilisation of the nuclease will require the introduction of additional reactive groups in parts of the protein that are not essential for the structure and function of the nuclease. To identify such parts and to substitute therein one or a few amino acid residues for lysine residues by site directed mutagenesis will be done in parallel to the mutational analysis of the active site of the enzyme.
The project therefore can be divided into four parts: production of nuclease mutants; characterisation of the various nuclease mutants in physico-chemical and biochemical terms; immobilisation of suitable mutants on solid support; and determination of the activity of the immobilised nuclease.
Topic(s)
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35392 Gießen
Germany