A note on geometrical properties of Banach spaces using ψ-direct sums

Let X be a Banach space and ψ a continuous convex function on [0,1] satisfying certain conditions. Let Xψ_⊕X be the ψ-direct sum of X. In this note, we characterize the strict convexity, uniform convexity and uniformly non-squareness of Banach spaces using ψ-direct sums, which extends the well-known characterization of these spaces.     

ATPase-coupled release control from polyion complex capsules encapsulating muscle proteins

In the present study, a muscle contractile protein complex, actomyosin, has been successfully encapsulated into gellan-chitosan polyion complex (PIC) capsules. The recovery of the myosin-ATPase activity is approximately 50% and the Mg2+-ATPase activity is stimulated by the presence of F-actin, which implies the formation of the actomyosin complex inside the capsule. Furthermore, encapsulation could protect the myosin, F-actin, and actomyosin inside from hydrolysis by proteases. Two small proteins, myoglobin and cytochrome c, have been used in the release tests. The release of myoglobin is not affected by the ionic strength of the external solution, while the release of cytochrome c increases with increasing ionic strength. The maximal releases are found in the external pH solution close to the isoelectric points of each protein. The Mg2+-ATP complex itself reduces the release percentages of the small proteins from the PIC capsule. The release amounts further decrease when coexisting with Mg2+-ATP and the encapsulated actomyosin, which indicates the release regulation by actomyosin. The present study suggests that the ATPase-coupled sliding motion of the myosin-F-actin filaments modifies the pore size of the polymer networks in the PIC capsule membranes.     

Realizing a two-dimensional ordered array of ferritin molecules directly on a solid surface utilizing carbonaceous material affinity peptides

A two-dimensional hexagonally close-packed (2D-HCP) array of ferritin molecules with a nanoparticle core was fabricated directly on a carbonaceous solid substrate by genetically modifying the outer surface of the ferritin with carbonaceous materials-specific binding peptides. The displayed peptides endowed ferritins with a specific protein-substrate interaction and masked the strong nonspecific interaction. The specific interaction was weak enough to allow ferritins to be rearranged as well as an attractive protein-protein interaction that could be adjusted by selecting the buffer conditions. This method not only produced 2D-HCP arrays of ferritin but also 2D-ordered arrays of independent inorganic nanoparticles after protein elimination that can be applied to floating gate memories.     

Variants of photosystem II D1 protein in Thermosynechococcus elongatus

Cyanobacteria have several psbA genes encoding PsbA, the D1 reaction center protein of the photosystem II (PSII) complex which bears, with PsbD, the D2 protein, most of the cofactors involved in electron-transfer reactions. The thermophilic cyanobacterium Thermosynechococcus elongatus has three psbA genes differently expressed depending on the environmental conditions. Among the 344 residues constituting each of the three possible PsbA variants there are 21 substitutions between PsbA1 and PsbA3, 31 between PsbA1 and PsbA2, and 27 between PsbA2 and PsbA3. In this review, we briefly summarize the changes already identified in the properties of the redox cofactors depending on the D1 variant constituting PSII in T. elongatus.     

Enantioselective aldol reaction of silyl ketene acetals promoted by a Lewis base-activated Lewis acid catalyst

The enantioselective aldol reaction of a silyl ketene acetal was promoted by chiral phosphine oxide-activated tetrachlorosilane to afford the corresponding adduct in high yield with moderate enantioselectivity.