340-90-9Relevant articles and documents
Investigations of the Alignment Process of PBPMLG: 2H NMR Analysis Reveals a Thermoresponsive 90° Flip of the Polymer
Schirra, Dominic S.,Hirschmann, Max,Radulov, Iliya A.,Lehmann, Matthias,Thiele, Christina M.
supporting information, p. 21040 - 21046 (2021/08/23)
The application of anisotropic parameters in NMR-spectroscopy enables the acquisition of spatial and angular information, complementary to those from conventional isotropic NMR-measurements. The use of alignment media is a well-established method for inducing anisotropy. PBPMLG is a recently discovered polyglutamate-based alignment medium, exhibiting thermoresponsive behavior in the lyotropic liquid crystalline (LLC) phase, thus offering potential for deeper understanding of the alignment process. We present one approach for investigating the thermoresponsive behavior by synthesizing specifically deuterated PBPMLG-isotopologues and their subsequent analyses using 2H NMR-spectroscopy. It was possible to relate the observed thermoresponsive behavior to a flip of the polymer with respect to the external magnetic field—an effect never observed before in glutamate-based polymeric alignment media. Furthermore, a solvent-induced temperature dependent gelation was verified in THF, which might provide yet another opportunity to manipulate the properties of this alignment medium in the future.
Light-Triggered Transformation of Molecular Baskets into Organic Nanoparticles
Border, Sarah E.,Pavlovi?, Radoslav Z.,Zhiquan, Lei,Gunther, Michael J.,Wang, Han,Cui, Honggang,Badji?, Jovica D.
, p. 273 - 279 (2018/10/24)
Discovering novel and functional photoresponsive materials is of interest for improving controlled release of molecules and scavenging toxic compounds for cleaning our environment or designing chemosensors. In this study, we report on the photoinduced decarboxylation of basket 16?, containing three glutamic acids at its rim. This concave compound is, in an aqueous environment (30 mm phosphate buffer at pH 7.0), monomeric (1H NMR DOSY, DLS) with glutamic acid residues randomly oriented about its rim (1H NMR and MM-OPLS3). The irradiation (300 nm) of 16? leads to the exclusive removal of its α-carboxylates to give amphiphilic 23? possessing γ-carboxylates. The photochemical transformation is a consecutive reaction with mono- and bis-decarboxylated products observed with 1H NMR spectroscopy and ESI mass spectrometry. Amphiphilic 23? is a preorganized molecule (MM-OPLS3) that, in water, aggregates into organic nanoparticles (ca. 50–200 nm in diameter; DLS, TEM and cryo-TEM) having a critical aggregation concentration of 12 μm (UV/Vis). As the transition of monomeric 16? into nanoparticulate 23? is triggered with light, we reasoned that stimuli-responsive formation of the soft material lends itself to nanotechnology applications such as controlled release or scavenging of targeted compounds.
A Genetically Encoded Allysine for the Synthesis of Proteins with Site-Specific Lysine Dimethylation
Wang, Zhipeng A.,Zeng, Yu,Kurra, Yadagiri,Wang, Xin,Tharp, Jeffery M.,Vatansever, Erol C.,Hsu, Willie W.,Dai, Susie,Fang, Xinqiang,Liu, Wenshe R.
supporting information, p. 212 - 216 (2016/12/30)
Using the amber suppression approach, N?-(4-azidobenzoxycarbonyl)-δ,?-dehydrolysine, an allysine precursor is genetically encoded in E. coli. Its genetic incorporation followed by two sequential biocompatible reactions allows convenient synthesis of proteins with site-specific lysine dimethylation. Using this approach, dimethyl-histone H3 and p53 proteins have been synthesized and used to probe functions of epigenetic enzymes including histone demethylase LSD1 and histone acetyltransferase Tip60. We confirmed that LSD1 is catalytically active toward H3K4me2 and H3K9me2 but inert toward H3K36me2, and methylation at p53 K372 directly activates Tip60 for its catalyzed acetylation at p53 K120.
