菌酶联合制备猪血抗氧化低聚肽

以猪血为原料,依次采用枯草芽孢杆菌发酵和碱性蛋白酶水解制备猪血抗氧化低聚肽,通过响应面试验优化发酵工艺和酶解工艺,最佳发酵参数为:底物浓度59.0 g/L、发酵时间56.5 h、接种量3.22∶100(体积比),此时多肽含量为2.31 mg/mL,·OH清除率为78.94%;最佳酶解参数为:酶解时间3.0 h、pH 9.5、酶解温度60℃、酶底比390 U/g,此条件下制备得到酶解液的多肽含量5.48 mg/mL,多肽含量较单一发酵提高2.39倍,·OH清除率为93.62%。采用超滤分离法,获得分子量分别为0~1 kDa、1 k Da^5 kDa和0~5 kDa的猪血抗氧化低聚肽,采用7种体外抗氧化指标(·OH清除率、·O^(2-)清除率,抑制脂质过氧化能力、还原力、ABTS^+·清除率、DPPH·清除率、总抗氧化力)评价3种不同分子量段的猪血低聚肽的抗氧化活性,结果表明:3种不同分子量段抗氧化肽活性大小为0~1 kDa>0~5 kDa>1 kDa^5 kDa,提示高抗氧化活性的猪血低聚肽的分子量集中在1 kDa以下。

酶解牦牛血发酵液制备抗氧化肽工艺优化

为进一步提高牦牛血枯草芽胞杆菌发酵液多肽含量,对牦牛血发酵液进行酶解,以酶解液的·OH清除率、多肽含量为主要指标,筛选酶解发酵液的最适蛋白酶,通过单因素和响应面试验优化酶解工艺,并对比菌酶联合制备产物与发酵液体外抗氧化活性。结果表明,碱性蛋白酶酶解发酵液最佳条件为:酶解时间3 h、p H值9.5、酶解温度60℃和酶底比190 U·g-1,此条件下制备得到酶解液多肽含量为5.52mg·mL^(-1),较发酵液提高2.39倍。菌酶联合制备产物对·O2-及脂质过氧化的IC50分别为6.22、4.87mg·mL^(-1),发酵法制备产物对·O2-及脂质过氧化的IC50分别为8.42、11.71 mg·mL^(-1),且菌酶联合制备产物的还原力优于发酵制备产物。因此,菌酶联合制备牦牛血抗氧化肽法优于传统单一发酵法。本研究结果对提高牦牛血抗氧化肽得率,增加牦牛产品附加值具有重要的意义。

Structure analysis and expressions of a novel tetratransmembrane protein,lysosoma-associated protein transmembrane 4β associated with hepatocellular carcinoma

AIM: To analyze the structure and expressions of the protein encoded by an HCC-associated novel gene, lysosomeassociated protein transmembrane 4 β (LAPTM4B). METHODS: Primary structure and fundamental characteristics of LAPTM4B protein were analysed with bioinformatics. Expressions of LAPTM4B in HCC tissues and various cell lines were detected using polyclonal antibodies and Western blot. RESULTS: LAPTM4B encoded two isoforms of proteins with molecular masses 35-ku and 24-ku, respectively. The expression level of LAPTM4B-35 protein in HCC tissues was dramatically upregulated and related to the differentiation status of HCC tissues, and it was also high in some cancer cell lines. Computer analysis showed LAPTM4B was an integral membrane protein with four transmembrane domains. LAPTM4B showed relatively high homology to LAPTM4A and LAPTM5 in various species. CONCLUSION: LAPTM4B gene encoded two isoforms of tetratansmembrane proteins, LAPTM4B-35 and LAPTM4B-24. The expression of LAPTM4B-35 protein is upregulated and associated with poor differentiation in human HCC tissues, and also at high levels in some cancer cell lines. LAPTM4B is an original and conserved protein.

Gastric juice for the diagnosis of H pylori infection in patients on proton pump inhibitors

AIM: To determine the efficacy of gastric juice polymerase chain reaction (PCR) for the detection of H pylori infection in comparison with histology and gastric antral biopsy PCR in patients on a proton pump inhibitor (PPI). METHODS: Eighty-five consecutive patients with dyspeptic symptoms were enrolled. Gastric biopsies for histology, PCR and gastric juice were collected at endoscopy for PCR of the H pylori urease C gene (ure C). Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, positive and negative likelihood ratio for PCR of gastric juice for the H pylori ure C gene was compared to histology and gastric antral biopsy H pylori ure C PCR in patients with and without PPI. RESULTS: Gastric juice PCR was positive in 66 (78%) patients. Histology showed H pylori associated gastritis in 57 (67%). Gastric biopsy PCR was positive in 72 (85%). In patients not taking PPI, the sensitivity, specificity, PPV, NPV, accuracy and positive and negative likelihood ratio for gastric juice PCR were 89%, 72%, 91%, 67%, 90%, 85%, 3.1 and 0.1 respectively. In patients on PPI these values were 86%, 100%%, 100%, 29%, 86%, 9.5 and 1.4, respectively. CONCLUSION: Gastric juice PCR for the diagnosis of H pylori infection has increased sensitivity compared to histology with PPI. The use of gastric juice PCR is recommended to confirm H pylori status in patients taking PPIs.