Hyperthermophilic nitrile hydratases?

There are plenty of reports of nitrilases which have been cloned from organisms with names that denote obviously heat-loving tendencies- an example is the “Cloning, overexpression, and characterization of a thermoactive nitrilase from the hyperthermophilic archaeon Pyrococcus abyssi” by Mueller, Egorova, Vorgias, Boutou, Trauthwein, Verseck and Antranikian in Protein Expr Purif. 2006, 47(2), 672-81. It is quite noticeable that NHases do not appear to have the same hyperthermophilicity. If you search the translated genomes of the four organisms which produce nitrilases in this paper (Pyrococcus abyssi, Pyrococcus horikoshii, Pyrococcus furiosus, and Aeropyrum pernix) by using BLASTp against the alpha subunit of my favourite cobalt centred NHase CGA009 or the “local” iron centred NHase AJ270, you get just about nothing that shows any similarity.

Something that does stand out from examination of all the current PDB files of NHases that almost everyone says their NHase is thermostable or thermophilic. I get the impression that this labelling of these generally sensitive enzymes in itself tells a story.