Recent advances in enzymatic properties, preparation methods, and functions of glycoside hydrolase from Bifidobacterium: a review.

Bifidobacterium is a major probiotic of intestinal gut flora and exerts many physiological activities, and it is widely applied in the fields of food and medicine. As an important part of Bifidobacterium, glycoside hydrolase plays a role in its physiological activity. With the continuous development and improvement of genetic engineering technology, research on this type of enzyme will play a crucial role in promoting the further development of Bifidobacterium in the field of probiotics. In this review, the preparation methods, enzymatic properties, and functions of glycoside hydrolase extracted from Bifidobacterium are described and summarized. The common method for preparing glycoside hydrolase derived from Bifidobacterium is heterologous expression in Escherichia coli BL21. The optimal pH range for these glycoside hydrolase enzymes is between 4.5 and 7.5; the optimal temperature is between 30 and 50 °C, which is close to the optimal growth condition of Bifidobacterium. Based on substrate specificity, these glycoside hydrolase could hydrolyze synthetic substrates and natural oligosaccharides, including a series of pNP artificial substrates, disaccharide, and trisaccharides, while they have little ability to hydrolyze polysaccharide substrates. This review will be expected to provide a basis for the development of Bifidobacterium as a probiotic element.

Study on the Biochemical Characterization and Selectivity of Three ß-Glucosidases From Bifidobacterium adolescentis ATCC15703.

Three ß-glucosidases from Bifidobacterium adolescentis ATCC15703, namely, BaBgl1A, BaBgl3A, and BaBgl3B, were overexpressed in Escherichia coli. The recombinant ß-glucosidases were sufficiently purified using Ni2+ affinity chromatography, and BaBgl1A exhibited the best purification efficiency with a purification factor of 2.3-fold and specific activity of 71.2 U/mg. Three recombinant ß-glucosidases acted on p-nitrophenyl-ß-glucopyranoside (pNPßGlc) at around pH 7.0 and 30-50°C. The results of the substrate specificity assay suggested that BaBgl1A acted exclusively as ß-1,2-glucosidase, while BaBgl3A and BaBgl3B acted mostly as ß-1,3-glucosidase and ß-1,4-glucosidase, respectively. The substrate specificity of the three recombinant enzymes was further studied using the ginsenosides Rb1 and Rd as substrates. The results of thin-layer chromatography and high-performance liquid chromatography analyses showed that BaBgl1A exhibited the highest bioconversion ability on Rb1 and Rd, where it hydrolyzed the outer C-3 glucose moieties of Rb1 and Rd into the rare ginsenosides Gypenoside XVII and F2; BaBgl3A exhibited medium bioconversion ability on Rb1, where it hydrolyzed both the outer C-3 and C-20 glucose moieties of Rb1 into Gyp XVII and Rd; and BaBgl3B was not active on Rb1 and Rd. These ß-glucosidases will act as new biocatalytic tools for transforming ginsenosides and preparing active glycosides and aglycone.

Analysis of Structure and Antioxidant Activity of Polysaccharides from Aralia continentalis.

We extracted, purified, and characterized three neutral and three acidic polysaccharides from the roots, stems, and leaves of Aralia continentalis Kitigawa. The results of the analysis of monosaccharide composition indicated that the polysaccharides from the roots and stems were more similar to each other than they were to the polysaccharides from the leaves. The in vitro antioxidant results demonstrated that the acidic polysaccharides had stronger antioxidant activity than the neutral fractions. Therefore, we investigated the primary purified acidic polysaccharide fractions (WACP(R)-A-c, WACP(S)-A-c, and WACP(L)-A-d) by NMR and enzymatic analysis. The structural analytical results indicated that WACP(R)-A-c contained homogalacturonan (HG); WACP(S)-A-c contained HG and rhamnogalacturonan II (RG-II), and WACP(L)-A-d contained HG, RG-II, and rhamnogalacturonan I (RG-I) domains. Our findings offer insights into the screening of natural polysaccharide-based antioxidants and provide a theoretical basis for the application of A. continentalis.

[Expressions of bFGF and PTEN in cervical carcinoma and their clinical significance].

OBJECTIVE: To investigate the expressions of bFGF and PTEN in cervical carcinoma and their clinical significance. METHODS: Tissue microarray technique and immunohistochemistry SP method were used to detect the expressions of bFGF and PTEN in 143 cases of invasive carcinoma of cervix (ICC) and 20 cases of normal cervical epithelium remote from tumor (NCE). The relationship between the expressions of bFGF and PTEN in ICC and some factors relating to clinical pathology of cervical carcinoma such as histopathological grading, lymph node metastasis, stroma involvement and FIGO staging were analyzed. RESULTS: The rate of the positive expression of bFGF in ICC was significantly higher than that in NCE 88.8% (127/143) vs. 25.0% (5/20, P = 0.000). The rate of positive expression of PTEN in ICC was significantly lower than that in NCE 67.1% (96/143) vs. 100.0% (20/20, P = 0.000). The expression of bFGF was positively correlated with lymph node metastasis and histopathological grading (r = 0.239, P = 0.004 and r = 0.369, P = 0.000, respectively). The expression of PTEN was negatively correlated with FIGO staging, histopathological grading and lymph node metastasis (r = -0.189, P = 0.024; r = -0.211, P = 0.011; r = -0.321, P = 0.000, respectively). The expression of bFGF was negatively correlated with the expression of PTEN in ICC (r = -0.261, P = 0.002). CONCLUSION: The overexpression of bFGF and underexpression of PTEN are closely related to the invasion and growth of cervical carcinoma. Detection of the expression of both bFGF and PTEN may be of value in further understanding the biological behavior and predicting the prognosis of cervical carcinoma.