Engineering a recombination neutral protease I from Aspergillus oryzae to improve enzyme activity at acidic pH.

ABSTRACT: Extracellular neutral proteases (NPs) in Aspergillus oryzae (A. oryzae) play a role in hydrolyzing soybean proteins into smaller peptides at pH about 7.5. The optimum pH of moromi fermentation (The second stage of soy sauce fermentation.) is 4.5-5.5. NPI is acid sensitive. To decrease the pH optimum of NPI, we got a mutant NPI-Y122FK246ID382V from the error-prone PCR library that showed optimal activity at pH 5.5. The specific activity at 40 °C of the NPI-Y122FK246ID382V mutant was 1383.50 U mg^-1, which was 2.75-fold that of wild-type (503.09 U mg^-1). The Michaelis constants of the mutant decreased from 22.13 mM (wild-type) to 19.98 mM (NPI-Y122FK246ID382V). The residues at positions 122 and 246 are important in influencing hydrolytic activity at pH 5.5

SUBMITTER: Hu Y 

PROVIDER: S-EPMC9056373 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature