Does the Enzyme Monoamine Oxidase, Isoenzyme A have an allosteric modulatory site?
I think an allosteric modulatory site has already been found, but it's not specific to Isoenzyme A, if that's what you were looking for.

See these papers:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1564771/

http://www.jbc.org/content/270/17/9856.full