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Xanthine oxidoreductase (XOR), the key enzyme catalyzing purine to produce uric acid, including two subtypes, xanthine dehydrogenase (XDH) and xanthine oxidase (XO), respectively, in vivo. Usually, XDH and XO can transform to each other. In this study, based on the principle that the subtype XO or XDH uses different electron acceptors, the methods for the measuring the activities of bovine milk XOR (pure enzyme) and its subtypes were established. The optimal concentrations of substrate xanthine (50 μmol·L-1) and electron acceptor NAD+ (50 μmol·L-1), pH value (7.80) were investigated. The ranges of the XOR, XO, XDH activity which could be determined were 0.97-17.5 U·L-1, 1-9 U·L-1, and 66-1 191 mU·L-1, respectively. Furthermore, the methods for determining the activities of XOR and its subtypes in mouse liver were established. The preparation of liver samples, the optimal concentrations of xanthine (100 μmol·L-1) and NAD+ (100 μmol·L-1) were researched. And the activity ranges of XOR, XO and XDH in mouse liver which could be determined were 0.67-3.98, 0.19-1.08, and 0.52-3.55 U·gprot-1, respectively. With the methods above, the effects of classic XOR inhibitor allopurinal (Allo) on XOR, XO and XDH from both milk and mouse liver were determined. All animal experiments have been approved by the Animal Experimental Center, Institute of Materia Medica, Chinese Academy of Medical Science and Peking Union Medical College (00003346). This study established new methods for the determination of XOR and its subtypes activity in pure enzyme system and in mouse liver, respectively, which were accurate and convenient. It laid the experimental foundation for exploring the different pathophysiological effects of XOR in the body and developing new XOR inhibitors.
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Acetylcholinesterase (AChE) is a key enzyme used to detect organophosphorus pesticide residues by the enzyme inhibition method. An accidental discovery of a mutant strain with AChE activity was made in our laboratory during the process of AChE expression by
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@#To investigate the freshness, high molecular weight substances, the determination of polypeptide, haemolysis and agglomeration, biological activity of Cervus and Cucumis polypeptide injection; to provide the direction for improving the quality of products for enterprises; furthermore, to provide reference for the revision of the quality standards of Cervus and Cucumis polypeptide injection. Firstly, we investigated the factors affecting the freshness of the injection, including biogenic amines, aflatoxins, the acid value and peroxide value of the melon seeds. The method of dansyl chloride pre-column derivatization-HPLC was used to determine the content of 8 biogenic amines in Cervus and Cucumis polypeptide injection. The method validation results showed good specificity, precision, linearity and recovery rates, which was suitable for the determination of biogenic amines in Cervus and Cucumis polypeptide injection. The results of sample determination showed that relatively higher concentrations of cadaverine were detected in the products from company B. The results of aflatoxins, acid value and peroxide value showed that the melon seeds from some companies had rancidity, mildew and other problems, indicating that the quality standards of multi-component biochemical drugs containing animal- and plant-derived components should be controlled in terms of freshness. Secondly, the methods for the determination of high molecular weight substances and polypeptides in the quality standard were improved. Tricine-SDS-PAGE electrophoresis was used instead of gel chromatography to determine the high molecular weight substances, which improved the accuracy of determination. The kits were used instead of folin-phenol for the determination of peptide content, which is easy to operate, specific and suitable for high-throughput sample determination. Finally, the haemolysis, agglomeration, and biological activity of Cervus and Cucumis polypeptide injection were studied. The results showed that no haemolysis and agglomeration were found in all samples, and the inhibitory effect of samples on THP-1 proliferation in vitro from different companies was different to some extent. In conclusion, the optimized quality standard is more suitable for the detection of Cervus and Cucumis polypeptide injection, and can lay the foundation for improving the safety of multi-component biochemical drugs.
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OBJECTIVE: To evaluate the quality status and current standard of cytochrome C injection and to carry out exploratory research on its standard. METHODS: Samples were tested according to the current quality standard in the Pharmacopoeia of the People's Republic of China (2010) Volume II- Exploratory researches including peptide mapping analysis, activity determination by TMB substrate ehromogenic method, and related substances detection by HPLC were carried out. RESULTS: The passing rate of cytochrome C injection was 100%, and that of freeze-dried cytochrome C powder for injections was 50%. CONCLUSION: There existed some problems with both the quality status and current standard of cytochrome C injection. The exploratory researches indicate that it is necessary to improve the statutory standard of cytochrome C.