The length of the alpha chain in a nitrile hydratase

If you look at number of amino acids in the alpha chain of a nitrile hydratase, I think it is safe to say that you get suspicious of its attribution as NHase if the number was much different from 200. I was wondering if this is actually a reasonable hunch to have so here is a graph.

I got this in the usual not terribly robust way of using a text search for "nitrile hydratase alpha", and then downloading only those which were RefSeq. Today that gives you 174 sequences of which some are definitely bobbins, but I feel bad at hand-pruning datasets if your initial search is a bit of a rough design to start with. The mean length I calculated to be 199, and as you can see the mode in the histogram above is for sequences between 200 and 210. Nice to see that for once, a hunch is backed by some data! Other things of note are that the Monsiga brevicollis NHase is found by this search and is the tiny block to the far right, and a quick scan through the sequences with n=60-140 indicates these are non-NHase waifs and strays picked up by my rough search terms.