31 research outputs found
N-linked oligosaccharide processing enzyme glucosidase II produces 1,5-anhydrofructose as a side product
α-1,4-Glucan lyase cleaves α-1,4-linkages of nonreducing termini of α-1,4-glucans to produce 1,5-anhydrofructose (1,5-AnFru). The enzymes isolated from fungi and algae show high homology with glycoside hydrolase family 31. Purification of α-1,4-glucan lyase from rat liver using DEAE Cellulose chromatography resulted in separation of two enzymatic active fractions, one was bound to the column and the other was in the flow-through. Partial amino acid sequence determined from the lyase, retained on the anion exchange column, were identical with that of the N-linked oligosaccharide processing enzyme glucosidase II. The lyase showed similar enzymatic properties as the microsomal glucosidase such as inhibition by 1-deoxynojirimycin and castanospermine. On the other hand, glucosidase II purified from rat liver microsomes produced not only glucose but also a small amount of 1,5-AnFru using maltose as substrate. Furthermore, CHO cells overexpressing pig liver glucosidase II showed a 1.5- to 2-fold higher lyase activity compared to the nontransfected CHO cells. Conversely, no lyase activity was detectable either in PHAR2.7, the glucosidase II-deficientmutant from a mouse lymphoma cell line, or in Saccharomyces cerevisiae strain YG427 having the glucosidase II gene disrupted. These data demonstrate that glucosidase II possesses an additional enzymatic activity of releasing 1,5-AnFru from maltos
Catalytic Cycle Employing a TEMPO–Anion Complex to Obtain a Secondary Mg–O<sub>2</sub> Battery
Nonaqueous Mg–O<sub>2</sub> batteries are suitable only
as primary cells because MgO precipitates formed during discharging
are not decomposed electrochemically at ambient temperatures. To address
this problem, the present study examined the ability of the 2,2,6,6-tetramethylpiperidine-oxyl
(TEMPO)–anion complex to catalyze the decomposition of MgO.
It was determined that this complex was capable of chemically decomposing
MgO at 60 °C. A catalytic cycle for the realization of a rechargeable
Mg–O<sub>2</sub> electrode was designed by combining the decomposition
of MgO via the TEMPO–anion complex and the TEMPO–redox
couple. This work also demonstrates that a nonaqueous Mg–O<sub>2</sub> battery incorporating acrylate polymer having TEMPO side
units in the cathode shows evidence of being rechargeable
Anode Material Associated with Polymeric Networking of Triflate Ions Formed on Mg
We have examined anode materials
with anions as an ion transport
species to solve metal deposition in rechargeable batteries intrinsically.
Mg deposition-dissolution tests were conducted using some ionic liquid
electrolytes at 60 °C, and a new electrochemical reaction was
observed in addition to Mg deposition and dissolution in an electrolyte
of Mg(CF<sub>3</sub>SO<sub>3</sub>)<sub>2</sub> and <i>N</i>-methyl-N-propylpiperidinium bis(trifluoromethane sulfonyl)amide.
The reaction was determined to be based on the formation and release
of a polymeric network of triflate ions (CF<sub>3</sub>SO<sub>3</sub><sup>–</sup>) on the Mg metal surface, which suggests a novel
anode material with anion carriers. An anion battery is also demonstrated
using this phenomenon and incorporating an acrylate polymer with 2,2,6,6-tetramethylpiperidine-oxyl
side units in the cathode to provide evidence of the rechargeability
by the intermediary anion carrier