Stabilization of Insoluble Discharge Products by Facile Aniline Modification for High Performance Li‐S Batteries

Continuous efforts have been made to attain high performance Li‐S batteries by preventing loss of soluble polysulfides, whereas issues related to insoluble discharge products, Li₂S₂ and Li₂S, have been underestimated. A facile and mild method, diazotization, that enables uniform functionalization on the surface of ordered mesoporous carbon (CMK‐3) with aniline functional groups while not deteriorating the original CMK‐3 microstructure is demonstrated. The aniline groups possess favorable interactions with insoluble discharge products. Thus, they homogeneously distribute the insoluble discharge products during cycling. The proposed materials exhibit outstanding electrochemical properties with regard to stability (920 mAh g^?1 at 0.2 C after 100 cycles) and rate capability (814 mAh g^?1 at 1 C) when evaluated as a cathode material for Li‐S batteries.     

Immobilization of alliinase with a water soluble–insoluble reversible N-succinyl-chitosan for allicin production

N-Succinyl-chitosan (NSC), a pH-sensitive polymer of reversibly soluble–insoluble characteristics with pH change, was prepared by modification of the chitosan backbone with succinic anhydride and employed as carrier for alliinase immobilization. The obtained NSC is soluble at pH above 4.8 and insoluble at pH below 4.4. The characteristics of NSC were evaluated using Fourier transform IR spectrophotometer, the X-ray diffraction spectrometry and thermogravimetric analyzer. Under an optimized condition (glutaraldehyde 0.8% (v/v), 31.2 U alliinase), the enzyme immobilization yield was 75.6%. The maximum activity of NSCA was achieved at 40 °C, pH 7, while the free enzyme exhibited maximum activity at 30 °C, pH 6. The Michaelis–Menten constant of NSCA was lower than that of free alliinase, indicating higher affinity of immobilized enzyme toward its substrate. The NSCA retained 85% of its initial activity even after being recycled 5 times. The immobilized alliinase in reversibly soluble NSC is suitable to catalyze the conversion of alliin to allicin, as active ingredient of pharmaceutical compositions and food additive.     

The multisubunit acetyl-CoA carboxylase is strongly associated with the chloroplast envelope through non-ionic interactions to the carboxyltransferase subunits

The committed step for de novo fatty acid biosynthesis is the carboxylation of acetyl-CoA catalyzed by acetyl-CoA carboxylase (ACCase). Plastidial ACCase from most plants is a multisubunit complex composed of multiple copies of four different polypeptides, biotin carboxyl carrier protein (BCCP), biotin carboxylase (BC), and carboxyltransferase (alpha-CT and beta-CT). Immunoblot analyses revealed these four proteins were mostly (69% of total) associated with a 17,000 g insoluble fraction from lysed pea chloroplasts. Under the same conditions only 8% of ribulose-1,5-bisphosphate carboxylase was associated with this insoluble fraction. BCCP and biotin carboxylase BC subunits freely dissociated from 17 kg insoluble fractions under high ionic strength conditions, whereas alpha-CT and beta-CT subunits remained tightly associated. Both CT subunits were highly enriched in envelope versus stroma and thylakoid preparations whereas BC and BCCP subunits were predominantly stromal-localized due to partial dissociation. Rapid solubilization of intact chloroplasts with Triton X-100 followed by centrifugation at 30 kg resulted in a pellet that was up to 8-fold enriched in ACCase activity and 21-fold enriched in BC activity. Triton-insoluble 30 kg pellets were reduced in lipid and chlorophyll content but enriched in chloroplast DNA due to the isolation of nucleoid particles. However, ACCase was not directly associated with nucleoids since enzymatic digestion of DNA or RNA had no effect on the association with Triton-insoluble matter. The amount of Triton-insoluble ACCase was similar in chloroplasts isolated from dark- or light-adapted leaves suggesting transitory starch granules were also not involved in this association. It is proposed that ACCase is associated with envelope membranes through interactions with an unidentified integral membrane protein.     

Identification of a Cytoskeleton-bound Form of Phospholemman with Unique C-Terminal Immunoreactivity

Phospholemman (PLM) is a 72-amino acid transmembrane protein thought to function in Na,K-ATPase regulation or assembly, similar to other members of the FXYD family of proteins. Unique to PLM among these regulatory proteins are sites for C-terminal phosphorylation by PKA and PKC, although a role for phosphorylation in PLM function remains unclear. To study PLM phosphorylation, we used PLM phosphopeptides to generate antibodies to specifically detect phosphorylated PLM. Peptide affinity chromatography isolated two populations of antibodies: one reacting with standard PLM, a collection of closely-spaced 15-kDa protein bands by SDS-PAGE. About 20% of PLM antibodies reacted specifically with a single distinct form of PLM. Levels of this second immunological form (PLM-b) were increased with overexpression of PLM cDNA, and also reacted with a monoclonal antibody against the PLM N-terminus. In complete contrast to standard PLM, however, PLM-b was quantitatively insoluble in nonionic detergents and was released from tight binding by colchicine. Antibodies to PLM-b were present in two different antisera raised to the phosphorylated C-terminal peptide (residues 57-70), but not in antiserum raised to the non-phosphorylated C-terminal peptide. Despite an apparent relationship between PLM-b and phosphorylated PLM, PLM-b levels were not affected by treatment of heart cells with isoproterenol. PLM-b appears to represent a cytoskeleton-attached detergent-insoluble form of PLM with distinctive C-terminal immunoreactivity that might have implications for PLM structure and function.     

The Enzymic Preparation of Diphosphoinositides

A procedure for the preparation of diphosphoinositides is described. Triphosphoinositides isolated from bovine brain are hydro-lysed by the triphosphoinositide phosphatase (EC 3.1.3.36) from Crithidia fasciculata in the presence of MgCl₂ and cetyltrimethyl-ammonium bromide. The diphosphoinositides produced are not degraded further and can be recovered from the reaction mixture in greater than 80% yield. The product is chromatographically pure and has the same structure (1-phosphatidylinositol 4-phosphate) as naturally occurring diphosphoinositides.     

Efficiency of pretreatments for optimal enzymatic saccharification of soybean fiber

The effectiveness of several pretreatments [high-power ultrasound, sulfuric acid (H₂SO₄), sodium hydroxide (NaOH), and ammonium hydroxide (NH₃OH)] to enhance glucose production from insoluble fractions recovered from enzyme-assisted aqueous extraction processing of extruded full-fat soybean flakes (FFSF) was investigated. Sonication of the insoluble fraction at 144 μm_{pp (peak-to-peak)} for 30 and 60 s did not improve the saccharification yield. The solid fractions recovered after pretreatment with H₂SO₄ [1% (w/w), 90 °C, 1.5 h], NaOH [15% (w/w), 65 °C, 17 h], and NH₃OH [15% (w/w), 65 °C, 17 h] showed significant lignin degradation, i.e., 81.9%, 71.2%, and 75.4%, respectively, when compared to the control (7.4%). NH₃OH pretreatment resulted in the highest saccharification yield (63%) after 48 h of enzymatic saccharification. A treatment combining the extraction and saccharification steps and applied directly to the extruded FFSF, where oil extraction yield and saccharification yield reached 98% and 43%, respectively, was identified.     

Major changes in the cell wall during silique development in Arabidopsis thaliana

Fruit development is a highly complex process, which involves major changes in plant metabolism leading to cell growth and differentiation. Changes in cell wall composition and structure play a major role in modulating cell growth. We investigated the changes in cell wall composition and the activities of associated enzymes during the dry fruit development of the model plant Arabidopsis thaliana. Silique development is characterized by several specific phases leading to fruit dehiscence and seed dispersal. We showed that early phases of silique growth were characterized by specific changes in non-cellulosic sugar content (rhamnose, arabinose, xylose, galactose and galacturonic acid). Xyloglucan oligosaccharide mass profiling further showed a strong increase in O-acetylated xyloglucans over the course of silique development, which could suggest a decreased capacity of xyloglucans to be associated with each other or to cellulose. The degree of methylesterification, mediated by the activity of pectin methylesterases (PMEs), decreased over the course of silique growth and dehiscence. The major changes in cell wall composition revealed by our analysis suggest that it could be major determinants in modulating cell wall rheology leading to growth or growth arrest.     

Starch turnover in shoot-forming tobacco callus

Tobacco callus grown under shoot-forming conditions or in the presence of gibberellic acid, which inhibits shoot formation, was incubated in [¹⁴C]-sucrose at three different periods in culture and then replanted. Evolution of ¹⁴CO₂ occurred during the 10 day post-incubation period. Most of the radioactivity was incorporated into the ethanol-soluble fraction, which lost most of its label after 24 h. Starch was the major ethanol-insoluble component and post-incubation synthesis occurred in this fraction for 24 h or longer. Greater net synthesis of starch occurred in shoot-forming tissue and the loss of label from starch began later than in tissue cultured in the presence of gibbe-rellic acid. Newly synthesized starch was not immediately utilised in the organogenic process, but its utilization could be correlated with the shoot-forming process.