Characterization of mung bean endogenous proteases and globulins and their effects on the production of mung bean protein.

• Endopeptidases and exopeptidases were examined in mung bean protein extract. • 8S and 11S globulins on SDS–PAGE gel were confirmed in our experimental conditions. • 11S (except at pH 3–3.5) and 8S globulins showed strong resistance to the endopeptidases. • Exopeptidases preferred to liberate methionine and tryptophan. • Endopeptidases and exopeptidases negatively affected the yield of mung bean protein. Mung bean protein possesses several health benefits, and aqueous processing methods are used for its production. However, mung bean protein yields are different with different methods, which are actually different in conditions (e.g., pH, temperature, and time). Herein, liquid chromatography tandem mass spectrometry identified 28 endopeptidases and exopeptidases in mung bean protein extract, and the positions of 8S and 11S globulins on sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) gel were confirmed in our experimental conditions. The SDS–PAGE, trichloroacetic acid–nitrogen solubility index, and free amino acid analysis revealed that (1) 8S globulins showed strong resistance to the endopeptidases (optimal at pH 5 and 50 °C) at pH 3–9, and 11S globulin exhibit strong resistance expect at pH 3–3.5; (2) the exopeptidases (optimal at pH 6 and 50 °C) preferred to liberate methionine and tryptophan. These proteases negatively affected protein yield, and short production time and low temperature were recommended. [ABSTRACT FROM AUTHOR]