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Wednesday 26 October 2011

Polymers and nitrile hydratase activity

There have been a few papers over the years looking at the possibility that nitrile-active enzymes might be able to attack nitrile groups on the surface of nitrile-containing polymers such as polyacrylonitrile.  An early example of this is the paper by Gübitz and co-workers [Nitrile Hydratase and Amidase from Rhodococcus rhodochrous Hydrolyze Acrylic Fibers and Granular Polyacrylonitriles, from Appl Environ Microbiol (2000)] which uses a cell free extract from Rhodococcus rhodochrous NCIMB 11216 to create pendant carboxylate groups on the fibres.

More recently there has been another paper looking at this topic using a different cell-free extract
This uses an extract from Amycolatopsis, and they do show conversion of the surface to carboxylate, by functionally tracking a NHase activity and an amidase activity. I am not sure how they know there isnt a nitrilase in there helping along too (NCBI records currently an Amycolatopsis species nitrilase).

In the light of the congested active site entrance which is generally found with NHase, it is quite interesting this works.

When nitrilases act like nitrile hydratases...

There were other posters than mine at Biotrans2011 which looked at nitrile active enzymes (from the groups of Norbert Klempier and Ludmila Martinkova). One of the issues that came up more than once was how sometimes nitrilases can sometimes stop being nitrile hydrolyzers and become nitrile hydraters (like NHases). This is an interesting topic in itself because, in terms of synthetic chemistry utility, nitrilases are probably more widely applicable than nitrile hydratases, and predicting when a particular nitrilase isnt quite up to the full hydrolysis could be a useful timesaver. In my experience, some IMAC purified nitrilases that we have worked with have upset commercial collaborators in stopping at the primary amide and not producing any carboxylic acid product, and the effect has been reported in the literature before, summarized in Martinkova and Kren 's recent nitrilase review.

Ludmila Martínková, Vladimír Křen, Biotransformations with nitrilases, Current Opinion in Chemical Biology, Volume 14, Issue 2, April 2010, Pages 130-137, 10.1016/j.cbpa.2009.11.018.

Obviously this leads me to the reverse query... Is it possible to get a nitrile hydratase to hydrate a nitrile under extreme/altered conditions?

Thursday 20 October 2011

My poster from Biotrans2011

Here is my poster from Biotrans2011. As you can see quite a lot of what I wrote has appeared on this blog previously.