Kubo M, Mitsuda Y, Takagi M, Imanaka T. Alteration of specific activity and stability of thermostable neutral protease by site-directed mutagenesis.
Appl Environ Microbiol 1992;
58:3779-83. [PMID:
1482198 PMCID:
PMC183176 DOI:
10.1128/aem.58.11.3779-3783.1992]
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Abstract
On the basis of three-dimensional information, many amino acid substitutions were introduced in the thermostable neutral protease (NprM) of Bacillus stearothermophilus MK232 by site-directed mutagenesis. When Glu at position 143 (Glu-143), which is one of the proposed active sites, was substituted for by Gln and Asp, the proteolytic activity disappeared. F114A (Phe-114 to Ala), Y110W (Tyr-110 to Trp), and Y211W (Tyr-211 to Trp) mutant enzymes had higher activity (1.3- to 1.6-fold) than the wild-type enzyme. When an autolysis site, Tyr-93, was replaced by Gly and Ser, the remaining activities of those mutant enzymes were higher than that of the wild-type enzyme.
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