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The “Histidine-brace” (His-brace) copper-binding site, composed of Cu(His)₂with a backbone amine, is found in metalloproteins with diverse functions. A primary example is lytic polysaccharide monooxygenase (LPMO), a class of enzymes that catalyze the oxidative depolymerization of polysaccharides, providing not only an energy source for native microorganisms but also a route to more effective industrial biomass conversion. Despite its importance, how the Cu His-brace site performs this unique and challenging oxidative depolymerization reaction remains to be understood. To answer this question, we have designed a biosynthetic model of LPMO by incorporating the Cu His-brace motif into azurin, an electron transfer protein. Spectroscopic studies, including ultraviolet-visible (UV–Vis) absorption and electron paramagnetic resonance, confirm copper binding at the designed His-brace site. Moreover, the designed protein is catalytically active towards both cellulose and starch, the native substrates of LPMO, generating degraded oligosaccharides with multiturnovers by C1 oxidation. It also performs oxidative cleavage of the model substrate 4-nitrophenyl-D-glucopyranoside, achieving a turnover number ~9% of that of a native LPMO assayed under identical conditions. This work presents a rationally designed artificial metalloenzyme that acts as a structural and functional mimic of LPMO, which provides a promising system for understanding the role of the Cu His-brace site in LPMO activity and potential application in polysaccharide degradation. 

NASA's New Horizons mission unveiled a diverse landscape of Pluto's surface with massive regions being neutral in color, while others like Cthulhu Macula range from golden-yellow to reddish comprising up to half of Pluto's carbon budget. Here, we demonstrate in laboratory experiments merged with electronic structure calculations that the photolysis of solid acetylene – the most abundant precipitate on Pluto's surface – by low energy ultraviolet photons efficiently synthesizes benzene and polycyclic aromatic hydrocarbons via excited state photochemistry thus providing critical molecular building blocks for the colored surface material. Since low energy photons deliver doses to Pluto's surface exceeding those from cosmic rays by six orders of magnitude, these processes may significantly contribute to the coloration of Pluto's surface and of hydrocarbon-covered surfaces of Solar System bodies such as Triton in general. This discovery critically enhances our perception of the distribution of aromatic molecules and carbon throughout our Solar System. 

The photophysical properties of naturally occurring chlorophylls depend on the regioisomeric nature of the β-pyrrolic substituents. Such systems are the “gold standard” by which such effects are judged. However, simple extrapolations from what has been learned with chlorophylls may not be appropriate for other partially reduced porphyrinoids. Here we report the synthesis of a series of cis / trans -porphodilactones ( cis / trans -1) and related derivatives ( cis / trans 2–5) designed to probe the effect of regioisomeric substitution in porphyrinoids that incorporate degrees of unsaturation through the β-pyrrolic periphery that exceed those of chlorophyll. These test systems were obtained through β-pyrrolic modifications of the tetrapyrrolic core, which included reduction of β-diazalone to the corresponding dilactol moieties and 1,3-dipolar cycloadditions. In the case of cis - vs. trans -3 bearing two pyrrolidine-fused β-rings we found an unprecedented Δ Q L up to ca. 71 nm (2086 cm −1 ), where Δ Q L ( Q L means the lowest energy transfer band, also the S 0 → S 1 transition band, which is often assigned as Q y (0,0) band) refers to the transition energy difference between the corresponding cis / trans -isomers. The Δ Q L values for these and other systems reported here were found to depend on the differences in the HOMO–LUMO energy gap and to be tied to the degeneracy and energy level splitting of the FMOs, as inferred from a combination of MCD spectral studies and DFT calculations. The aromaticity, estimated from the chemical shifts of the N–H protons and supported by theoretical calculations ( e.g. , AICD plots and NICS(1) values), was found to correlate with the extent of porphyrin periphery saturation resulting from the specific β-modifications. The aromaticity proved inversely proportional to the degree to which the regioisomerism affected the photophysical properties as noted from plots of Δ Q L s in cm −1 vs. the average NICS(1) values for 1–5. Such a finding is not something that can be easily interpolated from prior work and thus reveals how aromaticity may be used to fine-tune photophysical effects in reduced porphyrinoids. 

Measurements are presented of the cross-section for the central exclusive production ofJ/\psi\to\mu^+\mu^- $J/\psi \to {\mu }^{+}{\mu }^{-}$and\psi(2S)\to\mu^+\mu^- $\psi \left(2S\right)\to {\mu }^{+}{\mu }^{-}$processes in proton-proton collisions at\sqrt{s} = 13 \ \mathrm{TeV} $\sqrt{s}=13TeV$with 2016–2018 data. They are performed by requiring both muons to be in the LHCb acceptance (with pseudorapidity2<\eta_{\mu^±} < 4.5 $2<{\eta }_{{\mu }^{\pm }}<4.5$) and mesons in the rapidity range2.0 < y < 4.5 $2.0<y<4.5$. The integrated cross-section results are\sigma_{J/\psi\to\mu^+\mu^-}(2.0 ${\sigma }_{J/\psi \to {\mu }^{+}{\mu }^{-}}(2.0<y_{J/\psi }<4.5,2.0<{\eta }_{{\mu }^{\pm }}<4.5)=400\pm 2\pm 5\pm 12pb,{\sigma }_{\psi \left(2S\right)\to {\mu }^{+}{\mu }^{-}}(2.0<y_{\psi \left(2S\right)}<4.5,2.0<{\eta }_{{\mu }^{\pm }}<4.5)=9.40\pm 0.15\pm 0.13\pm 0.27pb,$where the uncertainties are statistical, systematic and due to the luminosity determination. In addition, a measurement of the ratio of\psi(2S) $\psi \left(2S\right)$andJ/\psi $J/\psi$cross-sections, at an average photon-proton centre-of-mass energy of1\ \mathrm{TeV} $1TeV$, is performed, giving$ = 0.1763 ± 0.0029 ± 0.0008 ± 0.0039,$$ where the first uncertainty is statistical, the second systematic and the third due to the knowledge of the involved branching fractions. For the first time, the dependence of theJ/\psi$ $J/\psi$and\psi(2S) $\psi \left(2S\right)$cross-sections on the total transverse momentum transfer is determined inpp $pp$collisions and is found consistent with the behaviour observed in electron-proton collisions.