Enzymic cleavage of polymer linkers
Linkers are molecules, which have two reactive groups. Through one of these groups, the linker can be fixed to an organic surface, leaving it with one other reactive group. This reactive group in turn can be used to bond to a bio-molecule, immobilising it, until the bond between linker and bio-molecule is cleaved. Enzymically cleavable linker structures, allowing such selective release of a product from a molecule are being researched. Of particular interest is enzymic cleavage, which can be performed in an aqueous environment under mild conditions. Recently, phenylacetamide containing linkers have been developed. The on-going research has determined that these linkers can be cleaved by penicillin G amidase, or PGA, an enzyme present in a particular strain of E-coli. Work is ongoing to improve the efficiency of the cleavage and to produce sufficient amounts of the enzyme to investigate its ability to cleave different linkers. An alternative to the E-coli enzyme is the PGA enzyme from A. faecalis. These two enzymes differ in the kinds of linker molecules they can cleave, their temperature stability and their ability to cleave phenylacetimide linkers. The researchers have established a system for the production of both of the enzymes in certain E-coli strains. The rates of production for both enzymes is promising and the PGAs can now be tested for their ability to cleave different phenylacetimide containing linkers. These developments offer the possibility for large scale production of PGAs , the use of which can be extended to a range of applications from the synthesis of antibiotics to other areas of selective sythesis.
