Endogenous Proteases in pH 7-OB Identified by LC–MS/MS
LC–MS/MS was also used to examine the endogenous proteases in pH 7-OB
(Table 2), and 16 kinds of proteases were identified. Based on the LFQ
intensities of all identified proteins, it was calculated that aspartic
endopeptidases showed the highest relative abundance of 3.334‰, followed
by tripeptidyl-peptidase 2 (0.486‰), serine carboxypeptidases (0.325%),
metalloendopeptidase (0.173‰), and subtilisin-like proteases (0.134‰;
serine endopeptidases). The other proteases showed extremely low
relative abundances. In one previous study, it was reported that
proteases in isolated sesame OBs could hydrolyze oleosins at pH 6.5 and
35 °C (Zhao et al., 2016), but no more information were available.