In order to obtain a readily derivatized analog of the ionophore antibiotic valinomycin, [1-lysine] valinomycin (Lys-VAL) was synthesized. The compound was built up on a polystyrene support by stepwise segment condensation and was cyclized in solution. The segments used were didepsipeptides protected by the t-butyloxycarbonyl and p-nitrobenzyloxycarbonyl groups. Derivatives prepared by acylation of the epsilon-amino group of Lys-VAL included [14C]acetyl-Lys-VAL, dansyl-Lys-VAL, palmitoyl-Lys-VAL and dithiodiglycoyl-bis-Lys-VAL. These derivatives had a high potassium binding capacity but were in general much less active than VAL in mediating ion transport in membranes.
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http://dx.doi.org/10.1111/j.1399-3011.1979.tb01944.x | DOI Listing |
ChemSusChem
January 2025
Forestry and Forest Products Research Institute: Shinrin Sogo Kenkyujo, Center for Advanced Materials, 1 Matsunosato, 305-8687, JAPAN.
Although microporous carbons can perform well for CO2 separations under high pressure conditions, their energy-demanding regeneration may render them a less attractive material option. Here, we developed a large-pore mesoporous carbon with pore sizes centered around 20-30 nm using a templated technical lignin. During the soft-templating process, unique cylindrical supramolecular assemblies form from the copolymer template.
View Article and Find Full Text PDFPRX Life
June 2024
Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA.
Biomolecular condensates are dynamic intracellular entities defined by their sequence- and composition-encoded material properties. During aging, these properties can change dramatically, potentially leading to pathological solidlike states, the mechanisms of which remain poorly understood. Recent experiments reveal that the aging of condensates involves a complex interplay of solvent depletion, strengthening of sticker links, and the formation of rigid structural segments such as beta fibrils.
View Article and Find Full Text PDFSci Adv
January 2025
The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
Controlling the reactivity of bonds along polymer chains enables both functionalization and deconstruction with relevance to chemical recycling and circularity. Because the substrate is a macromolecule, however, understanding the effects of chain conformation on the reactivity of polymer bonds emerges as important yet underexplored. Here, we show how oxy-functionalization of chemically recyclable condensation polymers affects acidolysis to monomers through control over distortion and interaction energies in the rate-limiting transition states.
View Article and Find Full Text PDFExp Eye Res
January 2025
Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India. Electronic address:
Autophagy is common in the aging retinal pigment epithelium (RPE). A dysfunctional autophagy in aged RPE is implicated in the pathogenesis of age-related macular degeneration. Aging human retina accompanies degenerative changes in photoreceptor mitochondria.
View Article and Find Full Text PDFTurk J Ophthalmol
December 2024
Kastamonu Training and Research Hospital, Clinic of Ophthalmology, Kastamonu, Türkiye.
We present the case of a patient who came to the emergency department with a significant decrease in vision and dilated pupil in the left eye. Since neurological pathologies were primarily considered, diffusion brain magnetic resonance imaging (MRI) and brain computed tomography (CT) were requested. After the results were reported as normal, we were consulted.
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