Methane monooxygenases (MMO), regarded as "an amazing biomolecular machine", catalyze the oxidation of methane to methanol under aerobic conditions. MMO catalyze the oxidation of methane elaborately, which is a novel way to catalyze methane to methanol. Furthermore, MMO can inspire the biomolecular machine design. In this review, we introduced MMO including structure, gene and catalytic mechanism. The history and the taxonomy of MMO were also introduced.
Catalysis ; Methane ; metabolism ; Methanol ; metabolism ; Oxygenases ; metabolism

Objective: To investigate the association of sugar sweetened beverage (SSB) consumption with insomnia and depressive symptoms among first grade middle school students from Yunnan Province, so as to provide evidence to guide interventions for the treatment of these symptoms in this population. Methods: From October to December 2022, 8 500 firstgrade middle school students from 11 counties in Yunnan Province were selected by cluster random sampling. Depressive symptoms, SSB consumption, and insomnia symptoms among students were evaluated by the Child Depression Scale (CDI), dietary frequency questionnaire, and Insomnia Severity Index (ISI). A Logistic regression model was employed to analyze the relationship between SSB consumption, insomnia, depressive symptoms, and their interaction effects among students. Results: The detection rate of depressive symptoms was 28.3%, and having insomnia symptoms ( OR=6.07, 95%CI =5.46-6.75), consuming carbonated beverages ( OR=1.20, 95%CI =1.08-1.34), tea ( OR=1.13, 95%CI =1.02-1.25), energy drinks ( OR=1.36, 95%CI =1.23-1.50), and other beverages ( OR=1.32, 95%CI =1.19-1.45) were positively correlated with depressive symptoms among first grade middle school students ( P < 0.05). Carbonated beverages (additive effect: OR=2.96, 95%CI =2.72-3.22, multiplicative effect: OR=4.75, 95%CI =4.25- 5.32 ), fruit drinks (additive effect: OR=2.61, 95%CI =2.40-2.82; multiplicative effect: OR=4.43, 95%CI =3.94-4.97), tea (additive effect: OR=2.70, 95%CI =2.47-2.89; multiplicative effect: OR=4.34, 95%CI =3.86-4.89), energy drinks (additive effect: OR=2.82, 95%CI =2.61-3.05; multiplicative effect: OR=4.48, 95%CI =3.92-5.12), sweetened milk (additive effect: OR= 2.73, 95%CI =2.06-2.96; multiplicative effect: OR=4.61, 95%CI =4.12-5.17) and other beverages (additive effect: OR= 2.73 , 95%CI =2.53-2.95; multiplicative effect: OR=4.56, 95%CI =4.00-5.20) had both additive and multiplicative effects with insomnia, and increased the risk of depressive symptoms in first grade middle school students ( P <0.01). Conclusions The interaction between the consumption of SSB and insomnia symptoms may increase the risk of depressive symptoms among first grade middle school students in Yunnan Province. It is necessary to advocate middle school students to reduce SSB intake, in order to decrease the occurrence of depressive symptoms among this population.