Fermentative oxidation of butane in bubble column reactors

To date the use of alkanes as starting materials for selective activation in chemical industry is very challenging. For this task the biocatalytic selective activation offers a number of advantages. The activation starts with C-H functionalization by a sequence of oxidation steps via alcohols, aldehydes/ ketones and carboxylic acids. All these derivatives are bulk-scale products, which are produced with standard chemical methods using high pressures and temperatures. In contrast, microorganisms are able to convert alkanes to various organic compounds at ambient pressure and temperature.[1] For the selective and efficient functionalization of alkanes appropriate fermentation of cells is required. Process engineering is required for a high yielding butane oxidation as well as reactor design. In this context it is essential to investigate the parameters of cell growth and to establish control of the fermentation conditions for production of the hydroxylated target compounds. At first a suitable reactor set up in accordance to the safety regulations required for handling a flammable gas like butane had to be installed to enable reaction engineering studies of the cell and reactor system. Specialized bubble column reactors are developed on lab scale and characterized in view of the implementation at industrial scale.[2] Additionally, a suitable control system was designed to monitor as well as control standard parameters and to simplify the implementation of further equipment. The mass transfer of the gaseous starting materials into the fermentation media is the key limiting factor for reaching sufficient productivities. The process window is mainly restricted by the requirements of the microorganisms and the flammability region of the substrates. Please click Additional Files below to see the full abstract

Human Prolactin Point Mutations and Their Projected Effect on Vasoinhibin Generation and Vasoinhibin-Related Diseases

BackgroundA dysregulation of the generation of vasoinhibin hormones by proteolytic cleavage of prolactin (PRL) has been brought into context with diabetic retinopathy, retinopathy of prematurity, preeclampsia, pregnancy-induced hypertension, and peripartum cardiomyopathy. Factors governing vasoinhibin generation are incompletely characterized, and the composition of vasoinhibin isoforms in human tissues or compartments, such as the circulation, is unknown. The aim of this study was to determine the possible contribution of PRL point mutations to the generation of vasoinhibins as well as to project their role in vasoinhibin-related diseases.MethodsProlactin sequences, point mutations, and substrate specificity information about the PRL cleaving enzymes cathepsin D, matrix metalloproteinases 8 and 13, and bone-morphogenetic protein 1 were retrieved from public databases. The consequences of point mutations in regard to their possible effect on vasoinhibin levels were projected on the basis of a score indicating the suitability of a particular sequence for enzymatic cleavage that result in vasoinhibin generation. The relative abundance and type of vasoinhibin isoforms were estimated by comparing the relative cleavage efficiency of vasoinhibin-generating enzymes.ResultsSix point mutations leading to amino acid substitutions in vasoinhibin-generating cleavage sites were found and projected to either facilitate or inhibit vasoinhibin generation. Four mutations affecting vasoinhibin generation in cancer tissues were found. The most likely composition of the relative abundance of vasoinhibin isoforms is projected to be 15 > 17.2 > 16.8 > 17.7 > 18 kDa vasoinhibin.ConclusionProlactin point mutations are likely to influence vasoinhibin levels by affecting the proteolysis efficiency of vasoinhibin-generating enzymes and should be monitored in patients with vasoinhibin-related diseases. Attempts to characterize vasoinhibin-related diseases should include the 15, 17.2, 16.8, 17.7, and 18 kDa vasoinhibin isoforms