RESUMO
The effect of methanol addition on the heterologous expression of isoprenyl transferase NovQ was studied in Pichia pastoris Gpn12, with menadione and isopentenol as precursors to catalyze vitamin K2 (MK-3) synthesis. The expression of NovQ increased by 36% when 2% methanol was added every 24 h. The influence of initial pH, temperature, methanol addition, precursors (menadione, isopentenol) addition, catalytic time and cetyltrimethyl-ammonium bromide (CTAB) addition were explored in the P. pastoris whole-cell catalytic synthesis process of MK-3 in shaking flask. Three significant factors were then studied by response surface method. The optimal catalytic conditions obtained were as follows: catalytic temperature 31.56 ℃, menadione 295.54 mg/L, catalytic time 15.87 h. Consistent with the response surface prediction results, the optimized yield of MK-3 reached 98.47 mg/L in shaking flask, 35% higher than that of the control group. On this basis, the production in a 30-L fermenter reached 189.67 mg/L when the cell catalyst of 220 g/L (dry weight) was used to catalyze the synthesis for 24 h. This method laid the foundation for the large-scale production of MK-3 by P. pastoris Gpn12.
RESUMO
AIM: To observe the effects of polysaccharides-2b from mudan cortex of Paeonia Suffruticosa Andr on glycocylation hemoglobion(GHb),blood glucose(BG),superoxide dismutase(SOD),the content of malonaldehyde(MDA) in serum and blood rheology of diabetic rats. METHODS: Diabetic rats were induced by associating streptozotocin(STZ) with freund's adjuvant complete(CFA),and then the diabetic rats were divided randomly into five groups: model group,polysaccharides-2b lower dose group(30 mg/kg),middle dose group(60 mg/kg),high dose group(120 mg/kg),positive group.Normal group was established additionally.PSM2b was perfused into stomach in diabatic rats for 60 days.The blood glucose was measured on the 10 th,30 th and 60 th days.The rehologic indexes,GHb,SOD and MDA were measured on the 60 th days. RESULTS: Compared with model group,every administrative group of PSM2b were able to apparently reduce high blood glucose and GHb(P