Propeptide of the metalloprotease of Brevibacillus brevis 7882 is a strong inhibitor of the mature enzyme.

A metalloprotease gene of Brevibacillus brevis (npr) was expressed in Escherichia coli in a soluble form as native Npr precursor. A significant fraction of the precursor was spontaneously processed, producing the N-terminal propeptide and the mature enzyme. A strong inhibition of the mature Npr by its own propeptide in the crude lysate was observed even in the absence of the covalent linkage between them. Pure precursor, propeptide and the mature Npr were isolated and kinetic parameters of the mature enzyme inhibition by the propeptide were determined. The inhibition is of the tight-binding competitive type with Ki 0.17 nM. Inhibition of metalloproteases from Brevibacillus megaterium and thermolysine by the heterologous propeptide of the Npr from B. brevis was much weaker or none.