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An extraction and purification method for soluble polyphenol oxidase (sPPO) and membrane-bound polyphenol oxidases (mPPO) from Agaricus bisporus was developed involving temperature-induced phase partitioning, fractional precipitation with ammonium sulfate, and DEAE anion exchange chromatography. The purity, molecular mass and enzymatic reaction kinetics of purified PPO were investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Native-PAGE and Michaelis-Menten equation. The specific activities of sPPO and mPPO toward catechol were 6 912.88 and 19 092.94 U/mg, and increased by 12.20 and 10.86 times, respectively, compared with that of crude PPO. The results of enzymatic reaction kinetics showed that the catalytic activities of sPPO and mPPO toward different substrates were greatly different and were higher toward catechol. mPPO had a stronger affinity to the substrate catechol and a higher reaction rate than sPPO. The optimum pH and temperature for both PPO enzymes were 6.8 and 30 ℃, respectively. This study may lay a foundation for future research on mass spectrometry identification and enzymatic properties two forms of PPOs from A. bisporu and inhibition of enzymatic browning caused by PPO.

Objective: To explore the eradication efficacies of triple versus quadruple furazolidone-based regimens for Helicobacter pylori (H. pylori) infection., Methods: A total of 357 outpatients with H. pylori infection were enrolled from June to December 2010. There were 200 males and 157 females with an average age of (42 ± 12) years. A diagnosis of duodenal ulcer was made according to their endoscopic examination results. They were randomly assigned into 4 treatment groups: 7-day triple (n = 89) and 10-day triple (n = 91), rabeprazole 10 mg, amoxicillin 1 000 mg and furazolidone 100 mg twice daily for 7 and 10 days respectively. 7-day quadruple (n = 88) and 10-day quadruple (n = 89), rabeprazole 10 mg, bismuth 220 mg, amoxicillin 1 000 mg and furazolidone 100 mg twice daily for 7 and 10 days respectively.H. pylori status was re-assessed with (14)C-urea breath test after 4-week therapy., Results: Among them, 323 cases completed the study. According to the analysis of intention-to-treat (ITT), the H. pylori eradication rates were 71.91% (64/89) in 7-day triple, 81.32% (74/91) in 10-day triple, 78.41% (69/88) in 7-day quadruple and 83.15% (74/89) in 10-day quadruple groups. No significant deviation existed among all groups (P > 0.05). According the per-protocol (PP) analysis, H. pylori eradication rates were 78.05% (64/82) in 7-day triple, 88.10% (74/84) in 10-day triple, 87.34% (69/79) in 7-day quadruple and 94.87% (74/78) in 10-day quadruple groups. Significant deviation existed among all groups (P = 0.017). The H. pylori eradication rate in 10-day quadruple group was significantly higher than that in 7-day triple group (P = 0.002). The total adverse reaction rate was 7.00% (25/357). No significant difference existed among all groups (P > 0.05)., Conclusions: Quadruple treatments provide higher H. pylori eradication rates than triple therapies. A 10-day treatment may improve H. pylori eradication rate. And 10-day quadruple regimen with furazolidone and bismuth may be effective for H. pylori infection.