This is a question which is still up for debate. It would
appear to be involved with incorporation of the cobalt ion in those NHases
which are cobalt-centred. In a newly accepted manuscript of FEMS Microbiology Letters entitled “The effect of flexibility and positive charge of the C‐terminal domain on the activator P14K function for nitrile hydratase in Pseudomonas putida” by Zhemin
Zhou and co-workers, mutants of the relevant proteins were modelled and made,
and then tested in the hydration of 3-cyanopyridine.
