Progress in bacterial urease complexes and their activation mechanisms / 生物工程学报

Urease decomposes urea to ammonia, and has application potential in agriculture and medical treatment. Urease proteins include structural proteins (UreA, UreB and UreC) and accessory proteins (UreD/UreH, UreE, UreF and UreG), each of them has its own unique role in urease maturation. The structural proteins form the active center of urease, and the accessory proteins are responsible for the delivery of nickel. We review here the structure and function of bacterial urease complexes, and how each protein interacts to complete the activation process. We hope to provide theoretical basis for the regulation of urease activity and the development of urease inhibitors.

Analysis of physiological and biochemical characteristics of SPF Yorkshire and Landrace swine / 中国实验动物学报

Objective To determine the reproductive physiology and blood physiological and biochemical characteristics of SPF Yorkshire and Landrace swine.Methods Ten reproductive physiology parameters,19 blood physiological parameters and 18 blood biochemical parameters in SPF Yorkshire and Landrace swine were measured using conventional methods and the differences between population,between age groups and between both sexes were analyzed.Results There were no significant differences(P>0.05) in reproductive physiology parameters and most blood physiological and biochemical parameters of the SPF Yorkshire and Landrace swine.A few of parameters,such as blood physiological indices GRAN,HGB,RDW,PLT,PCT,and blood biochemical indices ALKP,CHOL,TBIL,BUN,showed significant difference(P<0.05) between populations,between age groups and between both sexes,however,the values of difference were rather small,deviated from the normal range.Conclusion The physiological and biochemical characteristics of SPF Yorkshire and Landrace swine are basically stable and there is no significant difference compared with other laboratory miniature pigs.This study will provide valuable basic data for raising velvet yield,establishment of animal models and evaluating the genetic quality of closed colony.

Screening and characterization of lipase from a metagenome library of dairy rumen microflora / 生物工程学报

Using lipase segregation agar containing trioleoylglycerol, we obtained 18 lipase positive clones by screening from a metagenome library of dairy rumen microflora containing 15,360 clones. The average insert size of lipase positive clones was about 60 kb. Lipase enzyme activity analysis by p-NPP method indicated that Lipase6, Lipase7 and Lipase8 had higher lipolytic activities to substrates of p-nitrophenyl palmitate (C16), p-nitrophenyl alaurate (C12) and p-nitrophenyl palmitate (C16) respectively. The optimum pH of Lipase 6, Lipase 7 and Lipase 8 were 7.5. The halflife period of Lipase 8 with the value of 15 min in 70 degrees C decreased with the increase of temperature. In conclusion, the lipases screened in this study had different substrates specificity and good thermo stability, which laid a basis for large-scale industrial application.