RESUMO
A putative ß-glucosidase gene, BglAc, was amplified from Acidilobus sp. through metagenome database sampling from a hot spring in Yellowstone National Park. BglAc is composed of 485 amino acid residues and bioinformatics analysis showed that it belongs to the GH1 family of ß-glucosidases. The gene was successfully expressed in Escherichia coli with a molecular weight of approximately 55.3 kDa. The purified recombinant enzyme showed the maximum activity using p-nitrophenyl-ß-D-glucopyranoside (pNPG) as the substrate at optimal pH 5.0 and 100 °C. BglAc exhibited extraordinary thermostability, and its half-life at 90 °C was 6 h. The specific activity, Km, Vmax, and Kcat/Km of BglAc toward pNPG were 357.62 U mg-1, 3.41 mM, 474.0 µmol min-1·mg-1, and 122.7 s-1mM-1. BglAc exhibited the characteristic of glucose tolerance, and the inhibition constant Ki was 180.0 mM. Furthermore, a significant ethanol tolerance was observed, retaining 96% relative activity at 10% ethanol, and even 78% at 20% ethanol, suggesting BglAc as a promising enzyme for cellulose saccharification. BglAc also had a strong ability to convert the major soybean isoflavone glycosides (daidzin, genistin, and glycitin) into their corresponding aglycones. Overall, BglAc was actually a new ß-glucosidase with excellent thermostability, ethanol tolerance, and glycoside hydrolysis ability, indicating its wide prospects for applications in the food industry, animal feed, and lignocellulosic biomass degradation.
RESUMO
Melatonin appears to be a promising supplement for obesity treatment. The antiobesity effects of melatonin on obese rodents are influenced by various factors, including the species, sex, the dosage of melatonin, treatment duration, administration via, daily treatment time, and initial body weight (IBW). Therefore, we conducted a meta-analysis and machine learning study to evaluate the antiobesity effect of melatonin on obese mice or rats from 31 publications. The results showed that melatonin significantly reduced body weight, serum glucose (GLU), triglycerides (TGs), low-density lipoprotein (LDL), and cholesterol (TC) levels in obese mice or rats but increased high-density lipoprotein (HDL) levels. Melatonin showed a slight positive effect on clock-related genes, although the number of studies was limited. Meta-regression analysis and machine learning indicated that the dosage of melatonin was the primary factor influencing body weight, with higher melatonin dosages leading to a stronger weight reduction effect. Together, male obese C57BL/6 mice and Sprague-Dawley rats with an IBW of 100-200 g showed better body weight reduction when supplemented with a dose of 10-30 mg/kg melatonin administered at night via injection for 5-8 weeks.
