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Our previous study isolated a natural high-methoxyl homogalacturonan (HRWP-A) from Hippophae rhamnoides and showed antitumor activity in vivo. In this study, the immunomodulatory activity and mechanisms of action of HRWP-A were further investigated. Results showed that HRWP-A could recover the body condition and activated macrophage in Cyclophosphamide (CTX)-induced immunosuppressed mice. Further, we investigated the possible mechanism underlying the effects of HRWP-A on mouse peritoneal macrophages. qPCR and western blot revealed that HRWP-A upregulated the expression of TLR4 mRNA in vitro. This process was accompanied by a clear increase in MyD88 expression and p-IκB-α, but these effects were largely abrogated by pretreatment with anti-TLR4 antibodies. The effects of HRWP-A on macrophage NO, IL-1β and IL-6 production were also inhibited by anti-TLR4 antibodies and were greatly influenced by the NF-κB inhibitor PDTC. Moreover, HRWP-A failed to induce the production of NO, IL-1β and IL-6 in peritoneal macrophages prepared from C3H/HeJ mice, which have a point mutation in the Tlr4 gene, suggesting the involvement of the TLR4 molecule in HRWP-A-mediated macrophage activation. These results may have important implications for our understanding of the structure-activity relationship of immunopotentiating polysaccharides from medicinal herbs.

Trypsin from the pancreas of Tibetan sheep was purified to 7.4-fold by ammonium sulphate and acetone precipitation, followed by Sephacryl S-200 (Whatman, Maidstone, England) and Sephadex G-75 (Whatman) gel filtration, with an 23.2-fold increase in specific activity and 13.6% yield. The final enzyme preparation was nearly homogeneous on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and the molecular weight of the enzyme was estimated to be approximately 27 kDa by SDS-PAGE. Trypsin-like enzymes had maximal activities at around pH 9.0 and 60C for the hydrolysis of Nα-ρ-Tosyl–L–arginine methyl ester hydrochloride (TAME). Trypsin was unstable above 60C and below pH 4.0, and was stabilized by calcium ions. Purified trypsin had a Michaelis–Menten constant (Km) and catalytic constant (Kcat) of 0.53 mM and 206 s−1, respectively, when TAME was used as the substrate. The specific trypsin inhibitors, soybean trypsin inhibited, Nα-ρ-tosyl-L-lysine chloromethyl ketone and phenyl methyl sulfonyl fluoride, strongly inhibited the activity of trypsin, while other protease inhibitors exhibited negligible inhibition. The result suggests that major proteinase in the pancreas of Tibetan sheep was trypsin-like serine proteinase. PRACTICAL APPLICATIONS Tibetan sheep is one of the unique livestock resources in western China. It was found that the trypsin extraction and purification from waste pancreas have the biological characteristics of the heat resistance, alkali resistance, high specific activity and high hydrolysis efficiency. It does not only serve as a better research tool enzyme, but is also widely applied in the food, pharmaceutical, textile and other industries. This paper provides the scientific research basis of the development of the waste pancreas for the Tibetan sheep, therefore reducing environmental pollution.