Proteomic analysis of body wall and coelomic fluid in Sipunculus nudus

Insight into the thrombolytic ability of an extracellular fibrinolytic enzyme from Bacillus amyloliquefaciens GXU-1 isolated from Sipunculus nudus

Bacterial fibrinolytic enzymes have an important role in thrombolytic therapy due to their ability to dissolve fibrin. Therefore, purification, characterization and activity determination are of prime importance for bacterial fibrinolytic enzymes. In the current study, marine Bacillus amyloliquefaciens was first screened from Sipunculus nudus living in the Beibu Gulf of China and denoted as Guangxi University-1 (GXU-1). Then, an extracellular fibrinolytic enzyme (FEB-1) was purified from GXU-1 using ammonium sulfate precipitation, hydrophobic chromatography and gel filtration chromatography. The specific activity of FEB-1 was determined to be as high as 6789.74 U/mg. The relative molecular weight of FEB-1 was measured as 30 kDa through SDS‒PAGE. The optimum in vitro fibrinolytic activity of FEB-1 was identified at 37 °C and pH = 8. Furthermore, the activity of FEB-1 can be well preserved at 20-45 °C and pH = 6.0 to 9.0. The combination analysis of SDS‒PAGE and the molecular docking calculation revealed that FEB-1 can cleave more Aα- and Bβ-chains of fibrinogen than γ-chain. It is noteworthy that FEB-1 is comparatively stable under human-body environmental conditions, indicating its potential application in thrombosis therapy.

Purification and characterization of a glycoprotein from Sipunculus nudus and its immune-enhancing activity to RAW 264.7 macrophages

Sipunculus nudus, an edible marine invertebrate, has long been used as traditional Chinese medicine in folk remedies. In order to assess the immunoregulatory activity of glycoproteins in Sipunculus nudus and conduct a structure-activity relationship, a glycoprotein (SGP1) with molecular mass of 9.26 kDa was purified from Sipunculus nudus, and its chemical structure as well as immune-enhancing activity was investigated in this study. Structure analysis revealed that SGP1, a protein-dominate glycoprotein with O-glycosidic bonds, contained 92.8 % protein and 3.1 % saccharide. GC-MS result indicated that the saccharide moieties of SGP1 basically consisted of lyxose (Lyx), xylose (Xyl) as well as glucose (Glu) at a molar proportion of 0.87:4.16:1.36. The fourier transform infrared specoscopy (FT-IR) result proved that SGP1 have a typical characteristic of glycoprotein. Besides, circular dichroism (CD) result showed that SGP1 contained 4.1 % α-helix, 42.5 % β-sheet, 21.4 % β-turn, and 32.0 % random coil, indicating it's mainly a β-sheet glycoprotein. The amino acid sequence of SGP1 shared a similarity to the Myohemerythrin (sp|Q5K473|HEMTM) with protein sequence coverage of 28.3 %. Moreover, the activity evaluation results showed that SGP1 exhibited significant immune-enhancing activity to the RAW 264.7 macrophages by promoting macrophages proliferation, enhancing phagocytic capacity, and simultaneously stimulating the secretions of nitric oxide (NO), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) via NF-κB pathways. In this study, SGP1 as a novel glycoprotein had an obvious immune-enhancing activity to macrophages, and thus could be applied in the functional foods as a potential immunopotentiator for the hypoimmune population.

Fabrication and Characterization of W/O/W Emulgels by Sipunculus nudus Salt-Soluble Proteins: Co-Encapsulation of Vitamin C and β-Carotene

W/O/W emulsions can be used to encapsulate both hydrophobic and hydrophilic bioactive as nutritional products. However, studies on protein stabilized gel-like W/O/W emulsions have rarely been reported, compared to the liquid state multiple emulsions. The purpose of this study was to investigate the effect of different oil–water ratios on the stability of W/O/W emulgels fabricated with salt-soluble proteins (SSPs) of Sipunculus nudus. The physical stability, structural characteristics, rheological properties, and encapsulation stability of vitamin C and β-carotene of double emulgels were investigated. The addition of W/O primary emulsion was determined to be 10% after the characterization of the morphology of double emulsion. The results of microstructure and rheological properties showed that the stability of W/O/W emulgels increased with the increasing concentration of SSPs. Additionally, the encapsulation efficiency of vitamin C and β-carotene were more than 87%, and 99%, respectively, and still could maintain around 50% retention of the antioxidant capacity after storage for 28 days at 4 °C. The aforementioned findings demonstrate that stable W/O/W emulgels are a viable option for active ingredients with an improvement in shelf stability and protection of functional activity.