Phlorotannin Extracts from Ascophyllum nodosum Inhibited Proteases Activities and Structural Changes from Apostichopus japonicus

Abstract

Fresh Apostichopus japonicas (A. japonicas) are easy to autolyze through the actions of endogenous proteases under certain circumstances, further inducing a decline in A. japonicas product quality and business value. To solve this serious problem in the A. japonicas industry, we investigated the inhibition of phlorotannin extracts (PhTE) on the activities and structural changes of crude endogenous proteinase (CEP) from A. japonicas. The results of enzyme activity and SDS-PAGE indicated that PhTE could inhibit enzyme activity in a dose dependent manner. Analysis of multiple spectroscopic methods, scanning electron microscopy, and differential scanning calorimetry indicated that PhTE promoted the cross-linking and aggregation of CEP and increased the particle size of the enzyme, thus changing the structure of the enzyme protein and decreasing the thermostability of protease. In conclusion, PhTE might be an effective inhibitor on endogenous proteinase in A. japonicas, which opened up a new way to prevent the A. japonicas autolysis.

UVB irradiation improved the gel properties of phycocyanin‐undaria pinnatifida hydrogel

“…With reference to the Ming et al . (2022) method, the acquisition conditions are as follows: scanning times 32, resolution 4 cm −1 , scanning range 4000–1000 cm −1 . Background spectra were recorded prior to measurement of baseline corrections.…”

“…The freeze-dried materials were combined with potassium bromide (KBr), powdered into a powder, and sliced into thin objects. With reference to the Ming et al (2022) method, the acquisition conditions are as follows: scanning times 32, resolution 4 cm À1 , scanning range 4000-1000 cm À1 . Background spectra were recorded prior to measurement of baseline corrections.…”