Formal [3+2] Cycloaddition of Nitrosoallenes with Carbonyl and Nitrile Compounds to Form Functional Cyclic Nitrones

The synthesis of functional cyclic nitrones via [3+2] cycloadditions of allenamide-derived nitrosoallenes with carbonyl/nitrile compounds, including ketones, esters, and nitriles, is presented herein. Rapid carbon–carbon, carbon–oxygen, and carbon–nitrogen bond formations were achieved with <i>in situ</i> prepared nitrosoallenes, and densely substituted oxacyclic and carbocyclic nitrones containing tetrasubstituted carbon centers were successfully synthesized. The spirocyclic nitrone products synthesized from cyclic dicarbonyl compounds underwent the unique skeletal rearrangements to cyclic α-ketonitrones

A Back Hydrogen Exchange Procedure via the Acid-Unfolded State for a Large Protein

A deuterated protein sample is required for nuclear magnetic resonance (NMR) measurements of a large protein because severe signal broadenings occur because of the high molecular weight. The deuterated sample expressed in ²H₂O should subsequently be subjected to a back hydrogen exchange at amide groups. To perform the back exchange, the protein molecule is unfolded or destabilized so that internal residues become accessible to the solvent. However, the refolding yield from the destabilized or unfolded state of a large protein is usually low, leading to a dilemma in NMR measurements of large proteins. In our previous paper [Suzuki, M., et al. (2011) <i>Biochemistry</i> <i>50</i>, 10390–10398], we suggested that an acid-denatured microbial transglutaminase (MTG) consisting of 331 amino acid residues can be recovered effectively under low-salt conditions, escaping from the aggregation-prone intermediate. Here, we demonstrate that proMTG, the pro form of MTG consisting of 376 amino acid residues, can be refolded perfectly from the acid-unfolded state under low-salt conditions, as confirmed by circular dichroism and NMR spectroscopies. By performing the same procedure with a deuterated proMTG expressed in ²H₂O, we observed complete back exchanges for internal residues by NMR spectroscopy. Our procedure has potential applications to the back hydrogen exchange of large proteins for NMR measurements

Synthesis of α‑Substituted Enoximes with Nucleophiles via Nitrosoallenes

This paper reports nitrosoallene-mediated synthesis of α-substituted enoximes. Nucleophilic substitution of nitrosoallenes, a novel chemical species prepared from allenyl <i>N</i>-hydroxysulfonamides, afforded α-functionalized enoximes. Introduction of various nucleophiles proceeded smoothly to form C–N, C–O, C–S, C–F, and C–C bonds in the presence of azodicarboxylates

Synthesis of α‑Substituted Enoximes with Nucleophiles via Nitrosoallenes

This paper reports nitrosoallene-mediated synthesis of α-substituted enoximes. Nucleophilic substitution of nitrosoallenes, a novel chemical species prepared from allenyl <i>N</i>-hydroxysulfonamides, afforded α-functionalized enoximes. Introduction of various nucleophiles proceeded smoothly to form C–N, C–O, C–S, C–F, and C–C bonds in the presence of azodicarboxylates

Incorporation of ¹⁵N-Labeled Ammonia into Glutamine Amide Groups by Protein-Glutaminase and Analysis of the Reactivity for α-Lactalbumin

Protein-glutaminase (PG) is an enzyme that catalyzes the deamidation of protein-bound glutamine residues. We found that an enzyme labeling technique (ELT), which is a stable isotope labeling method based on transglutaminase (TGase) reaction, is applicable for PG. PG catalyzed incorporation of ¹⁵N-labeled ammonium ions into reactive glutamine amide groups in α-lactalbumin similarly to TGase and deamidated the most reactive glutamine amide group once labeled with ¹⁵N. Furthermore, we investigated the effect of ammonium ions on the PG activity by peptide mapping, and more reactive glutamine residues were detected than were detected by the ELT in the presence of ammonium ions. This is probably because ammonium ions are competitive inhibitors, causing decreased reactivity for glutamine residues. We propose the reaction scheme of PG in the presence of the ¹⁵N-labeled ammonium ions and show that the ELT method with PG is useful for evaluating the activity of PG

Additional file 2 of Sociodemographic and physical predictors of non-participation in community based physical checkup among older neighbors: a case-control study from the Kyoto-Kameoka longitudinal study, Japan

Table S2. The Kihon-Checklist with 25 questions. (DOCX 20 kb