Soybean P34 Probable Thiol Protease Probably Has Proteolytic Activity on Oleosins

Abstract

P34 probable thiol protease (P34) and Gly m Bd 30K (30K) show high relationship with the protease of 24 kDa oleosin of soybean oil bodies. In this study, 9 day germinated soybean was used to separate bioprocessed P34 (P32) from bioprocessed 30K (28K). Interestingly, P32 existed as dimer, whereas 28K existed as monomer; a P32-rich sample had proteolytic activity and high cleavage site specificity (Lys-Thr of 24 kDa oleosin), whereas a 28K-rich sample showed low proteolytic activity; the P32-rich sample contained one thiol protease. After mixing with purified oil bodies, all P32 dimers were dissociated and bound to 24 kDa oleosins to form P32-24 kDa oleosin complexes. By incubation, 24 kDa oleosin was preferentially hydrolyzed, and two hydrolyzed products (HPs; 17 and 7 kDa) were confirmed. After most of 24 kDa oleosin was hydrolyzed, some P32 existed as dimer, and the other as P32-17 kDa HP. It was suggested that P32 was the protease.

Novel strategy for the demulsification of isolated sesame oil bodies by endogenous proteases

“…Due to the slight band intensity changes of 11S and 7S globulins and caleosins at 30 °C, it was suggested that the band intensity increase at the position for oleosin‐L was induced by the hydrolyzed products of oleosin‐H, which had similar MW to oleosin‐L. This phenomenon was also occurred in the isolated soybean OB, in which P34 probable thiol protease hydrolyzed 24 kDa oleosins into hydrolyzed products with similar MW to 16 kDa oleosins (Zhao et al, 2017). With increasing temperature from 40 to 70°C, oleosin‐H disappeared, and re‐appeared at 80°C.…”

“…Several studies have confirmed that plant seed endogenous endopeptidases are contained in the isolated OB, and they can hydrolyze the intrinsic and extrinsic proteins of OB (Chen et al, 2018; Vandana & Bhatla, 2006; Zhao et al, 2016, 2017). However, few studies have checked whether these endogenous endopeptidases can efficiently demulsify the OB.…”

“…Generally, aqueous extraction processing contains the following steps: (1) pretreatment, such as soaking, grinding, and flaking, (2) aqueous extraction at neutral and/or alkaline pH, (3) separation by centrifugation, and (4) subsequent processing of proteins and lipids. During aqueous extraction, lipids mainly in oil bodies (OB) and proteins including storage proteins and various enzymes are released into aqueous phase and interact with each other (Chen et al, 2018; Zhao et al, 2016, 2017). By centrifugation, the OB float as the upper creamy phase.…”

Effect of water bath‐assisted water extraction on physical and chemical properties of soybean oil body emulsion

“…Exogenous proteins include lipoxygenase and glycinin (A 3 , acidic peptide chain, basic peptide chain), β‐conglobulin (α, α', and β), γ‐conglobulin, Bd 30K, and P34 (Chen, Cao et al., 2014; Chen, Zhao et al., 2014). It was reported that P34 was an protease that had proteolytic activity and high cleavage site specificity (Lys‐Thr of 24 kDa oleosin) (Zhao et al., 2017). Some researches showed that endogenous protease P34 of SOB enrichment extracted at the conditions of pH 6.5, room temperature, and water phase could hydrolyze 24 kDa oleosin to peptides (16 kDa and 8 kDa) within 1 hr (Zhao, Chen, Cao, et al., 2013; Zhao, Chen, Zhang, et al., 2013).…”

“…Exogenous proteins include lipoxygenase and glycinin (A 3 , acidic peptide chain, basic peptide chain), β-conglobulin (α, α', and β), γ-conglobulin, Bd 30K, and P34 . It was reported that P34 was an protease that had proteolytic activity and high cleavage site specificity (Lys-Thr of 24 kDa oleosin) (Zhao et al, 2017).…”