Another 4D mutant of Rhodococcus rhodochrous PA-34 paper

There is a new paper on the 4D mutant of Rhodococcus rhodochrous PA34 from Pratush, Seth and Bhalla.

Purification and characterization of nitrile hydratase of mutant 4D of Rhodococcus rhodochrous PA-34 in 3 Biotech, DOI: 10.1007/s13205-012-0081-5.

They give methodology for how to purify the NHase out of the mutant cells, and then test it against a set of standard compounds under a range of conditions.

As a cobalt-centred NHase, you might expect it to turnover aryl nitriles better than alkyl nitriles if the simplistic “rule of thumb” operated but this seems to be pretty undifferentiated. (see one panel from their Figure 4 below).

This mutant also seems to have a temperature maximum somewhere in the region of 45-60^oC (they go for 55^oC) which as the authors note is sort of high for a NHase (and higher than for wild type Rhodococcus rhodochrous PA34 which is quoted as 40^oC). Another panel of their Figure 4 shows this below.