No abstract

The molecular dissociation constant, Kd, is a well-established parameter to quantitate the affinity of protein-protein or other molecular interactions. Recently, we reported the theoretical basis and experimental procedure for Kd determination using a quantitative FRET method. Here we report a new development of Kd determination by measuring the reduction in donor fluorescence due to acceptor quenching in FRET. A new method of Kd determination was developed from the quantitative measurement of donor fluorescence quenching. The estimated Kd values of SUMO1-Ubc9 interaction based on this method are in good agreement with those determined by other technologies, including FRET acceptor emission. Thus, the acceptor-quenched approach can be used as a complement to the previously developed acceptor excitation method. The new methodology has more general applications regardless whether the acceptor is an excitable fluorophore or a quencher. Thus, these developments provide a complete methodology for protein or other molecule interaction affinity determinations in solution.

Water-flow-regulating ecosystem services (ESs) determine the regulation of hydrological flows on the ground’s surface. A lack of water-flow-regulating ESs would cause environmental problems such as heavy rainfall runoff and urban water logging, leading to floods affecting well-being, especially in dense urban areas. Research on water-flow-regulating ES supply–demand relationships in urban areas is urgently needed to better support the management of urban surface runoff. However, matching the supply–demand relationships of water-flow-regulating ESs remains challenging. In this contribution, a cross-scale approach linking the supply–demand assessment of water-flow-regulating ESs on a macroscale and the evaluation of the constructed urban environment on a microscale was developed. The approach was applied in the city of Bochum, Germany, as a trial of bridging the “science–practice gap”. Our findings show that the supply–demand budget of water-flow-regulating ESs in Bochum exhibits an urban–rural difference and is also partially influenced by land cover transformations such as vegetation degradation. In addition, further assessment of the constructed urban environment confirmed the result from the assessment of water-flow-regulating ESs based on the understanding of the urban hydrological cycle in Bochum. To account for the mismatch in the supply–demand budget, we classified the typical superior and inferior forms of urban water-flow-regulating ESs through field research on the same extreme areas to summarize the operable optimization, enhancement, and protection suggestions for urban construction decision makers. Finally, the cross-scale approach was approved as a possible way to bridge the “science–practice” gap for water-flow-regulating ES research in urban areas.