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ATP-sensitive potassium (KATP) channels couple the intracellular ATP concentration to insulin secretion. KATP channel activity is inhibited by ATP binding to the Kir6.2 tetramer and activated by phosphatidylinositol 4,5-bisphosphate (PIP2). Here, we use molecular dynamics simulation, electrophysiology and fluorescence spectroscopy to show that ATP and PIP2 occupy different binding pockets that share a single amino acid residue, K39. When both ligands are present, simulations suggest that K39 shows a greater preference to co-ordinate with PIP2 than with ATP. They also predict that a neonatal diabetes mutation at K39 (K39R) increases the number of hydrogen bonds formed between K39 and PIP2, potentially accounting for the reduced ATP inhibition observed in electrophysiological experiments. Our work suggests that PIP2 and ATP interact allosterically to regulate KATP channel activity. (Figure presented.). Key points: The KATP channel is activated by the binding of phosphatidylinositol 4,5-bisphosphate (PIP2) lipids and inactivated by the binding of ATP. K39 has the potential to bind to both PIP2 and ATP. A mutation to this residue (K39R) results in neonatal diabetes. This study uses patch-clamp fluorometry, electrophysiology and molecular dynamics simulation. We show that PIP2 competes with ATP for K39, and this reduces channel inhibition by ATP. We show that K39R increases channel affinity to PIP2 by increasing the number of hydrogen bonds with PIP2, when compared with the wild-type K39. This therefore decreases KATP channel inhibition by ATP., QC 20230524

The use of 1-D computational models has enabled dewatering performance to be accurately predicted in sedimentation, centrifugation and filtration processes in the laboratory and industry, but for processes involving shear, such as gravity thickening, performance significantly exceeds predictions by up to a factor of 100 for a given underflow solids concentration and bed height. The improvement is attributed to shear-induced structural changes which affect the material properties that describe dewatering. A phenomenon that can account for the changes is particulate network densification, and a theory of aggregate densification has been developed. A pilot thickening column was used to test dewatering under continuous operating conditions at bed heights of 1, 2 and 3 m using calcite flocculated with a high molecular weight polyacrylamide. The hindered settling function as determined from the solids concentration profile within the column was compared to that of an unsheared sample from the column feed. There was a significant decrease in the hindered settling function and therefore an increase in the permeability of the suspension. The hindered settling function results were analysed with aggregate densification theory to infer the extent of aggregate densification, quantified as the ratio of the aggregate diameter relative to the original aggregate size. The aggregates appeared to continue densifying throughout the column until they were removed from the underflow for both the 1 m and 2 m bed heights. For the 1m bed height the aggregates will densify to 92% of the original aggregate size for a residence time up to 1 500 s, whereas for the 2 m bed the aggregates will densify to 88% in 3 500 s. The aggregates appear to densify to 88% of the original aggregate size for the 3 m bed. The results show that aggregate densification is capable of enabling performance enhancement which matches the pilot column observations and can account for some of the discrepancy between obs, The use of 1-D computational models has enabled dewatering performance to be accurately predicted in sedimentation, centrifugation and filtration processes in the laboratory and industry, but for processes involving shear, such as gravity thickening, performance significantly exceeds predictions by up to a factor of 100 for a given underflow solids concentration and bed height. The improvement is attributed to shear-induced structural changes which affect the material properties that describe dewatering. A phenomenon that can account for the changes is particulate network densification, and a theory of aggregate densification has been developed. A pilot thickening column was used to test dewatering under continuous operating conditions at bed heights of 1, 2 and 3 m using calcite flocculated with a high molecular weight polyacrylamide. The hindered settling function as determined from the solids concentration profile within the column was compared to that of an unsheared sample from the column feed. There was a significant decrease in the hindered settling function and therefore an increase in the permeability of the suspension. The hindered settling function results were analysed with aggregate densification theory to infer the extent of aggregate densification, quantified as the ratio of the aggregate diameter relative to the original aggregate size. The aggregates appeared to continue densifying throughout the column until they were removed from the underflow for both the 1 m and 2 m bed heights. For the 1m bed height the aggregates will densify to 92% of the original aggregate size for a residence time up to 1 500 s, whereas for the 2 m bed the aggregates will densify to 88% in 3 500 s. The aggregates appear to densify to 88% of the original aggregate size for the 3 m bed. The results show that aggregate densification is capable of enabling performance enhancement which matches the pilot column observations and can account for some of the discrepancy between obs