Glutamyl endopeptidase of Bacillus intermedius, strain 3-19

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A homogeneous glutamyl endopeptidase splitting peptide bonds of glutamic, rarely of aspartic acid residues in peptides and proteins, was isolated from Bacillus intermedius 3-19 culture filtrate using chromatography on CM cellulose and Mono S. The enzyme molecular mass is equal to 29 kDa, pI 8.4. The protease is inhibited by diisopropylfluorophosphate. The enzyme, like other glutamyl endopeptidases, reveals two pH optima at pH 7.5 and 9.0 for casein and one at pH 8.0 for Z-Glu-pNA hydrolysis. A 6 mM K(m) is found for hydrolysis of the latter substrate. The enzyme activity optimum lies at 55 degrees C, and it is stable at pH 6.5-11.0. Its N-terminal sequence shows 56% coinciding residues when compared with that of Bacillus licheniformis glutamyl endopeptidase.