Effect of Solvent Choice on the Self-Assembly Properties of a Diphenylalanine Amphiphile Stabilized by an Ion Pair

A diphenylalanine (FF) amphiphile blocked at the C terminus with a benzyl ester (OBzl) and stabilized at the N terminus with a trifluoroacetate (TFA) anion was synthetized and characterized. Aggregation of peptide molecules was studied by considering a peptide solution in an organic solvent and adding pure water, a KCl solution, or another organic solvent as co-solvent. The choice of the organic solvent and co-solvent and the solvent/co-solvent ratio allowed the mixture to be tuned by modulating the polarity, the ionic strength, and the peptide concentration. Differences in the properties of the media used to dissolve the peptides resulted in the formation of different self-assembled microstructures (e.g. fibers, branched-like structures, plates, and spherulites). Furthermore, crystals of TFAFF-OBzl were obtained from the aqueous peptide solutions for X-ray diffraction analysis. The results revealed a hydrophilic core constituted by carboxylate (from TFA), ester, and amide groups, and the core was found to be surrounded by a hydrophobic crown with ten aromatic rings. This segregated organization explains the assemblies observed in the different solvent mixtures as a function of the environmental polarity, ionic strength, and peptide concentration

Discovery and mass measurement of the hot, transiting, Earth-sized planet, GJ 3929 b

Full list of authors: Kemmer, J.; Dreizler, S.; Kossakowski, D.; Stock, S.; Quirrenbach, A.; Caballero, J. A.; Amado, P. J.; Collins, K. A.; Espinoza, N.; Herrero, E.; Jenkins, J. M.; Latham, D. W.; Lillo-Box, J.; Narita, N.; Pallé, E.; Reiners, A.; Ribas, I.; Ricker, G.; Rodríguez, E.; Seager, S.; Vanderspek, R.; Wells, R.; Winn, J.; Aceituno, F. J.; Béjar, V. J. S.; Barclay, T.; Bluhm, P.; Chaturvedi, P.; Cifuentes, C.; Collins, K. I.; Cortés-Contreras, M.; Demory, B. -O.; Fausnaugh, M. M.; Fukui, A.; Gómez Maqueo Chew, Y.; Galadí-Enríquez, D.; Gan, T.; Gillon, M.; Golovin, A.; Hatzes, A. P.; Henning, Th.; Huang, C.; Jeffers, S. V.; Kaminski, A.; Kunimoto, M.; Kürster, M.; López-González, M. J.; Lafarga, M.; Luque, R.; McCormac, J.; Molaverdikhani, K.; Montes, D.; Morales, J. C.; Passegger, V. M.; Reffert, S.; Sabin, L.; Schöfer, P.; Schanche, N.; Schlecker, M.; Schroffenegger, U.; Schwarz, R. P.; Schweitzer, A.; Sota, A.; Tenenbaum, P.; Trifonov, T.; Vanaverbeke, S.; Zechmeister, M.We report the discovery of GJ 3929 b, a hot Earth-sized planet orbiting the nearby M3.5 V dwarf star, GJ 3929 (G 180-18, TOI-2013). Joint modelling of photometric observations from TESS sectors 24 and 25 together with 73 spectroscopic observations from CARMENES and follow-up transit observations from SAINT-EX, LCOGT, and OSN yields a planet radius of Rb = 1.150 ± 0.040 R⊕, a mass of Mb = 1.21 ± 0.42 M⊕, and an orbital period of Pb = 2.6162745 ± 0.0000030 d. The resulting density of ρb = 4.4 ± 1.6 g cm−3 is compatible with the Earth’s mean density of about 5.5 g cm−3. Due to the apparent brightness of the host star (J = 8.7 mag) and its small size, GJ 3929 b is a promising target for atmospheric characterisation with the JWST. Additionally, the radial velocity data show evidence for another planet candidate with P[c] = 14.303 ± 0.035 d, which is likely unrelated to the stellar rotation period, Prot = 122 ± 13 d, which we determined from archival HATNet and ASAS-SN photometry combined with newly obtained TJO data. © ESO 2022.This paper is based on observations made with the MuSCAT3 instrument, developed by the Astrobiology Center and under financial supports by JSPS KAKENHI (JP18H05439) and JST PRESTO (JPMJPR1775), at Faulkes Telescope North on Maui, HI, operated by the Las Cumbres Observatory. This work includes observationscarried out at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir (OAN-SPM), Baja California, México. We acknowledge financial support from the Agencia Estatal de Investigación of the Ministerio de Ciencia, Innovación y Universidades and the ERDF through projects PID2019-109522GB-C5[1:4], PID2019-107061GB-C64, PID2019-110689RB-100, ESP2017-87676-C5-1-R, and the Centre of Excellence “Severo Ochoa” and “María de Maeztu” awards to the Instituto de Astrofísica de Canarias (CEX2019-000920-S), Instituto de Astrofísica de Andalucía (SEV-2017-0709), and Centro de Astrobiología (MDM-2017-0737), the Swiss National Science Foundation (PP00P2-163967 and PP00P2-190080), the Centre for Space and Habitability of the University of Bern, the National Centre for Competence in Research PlanetS, supported by the Swiss National Science Foundation, the Deutsche Forschungsgemeinschaft priority program SPP 1992 “Exploring the Diversity of Extrasolar Planets” (JE 701/5-1), the Excellence Cluster ORIGINS, which is funded by the Deutsche Forschungsgemeinschaft under Germany’s Excellence Strategy (EXC-2094 – 390783311), NASA (NNX17AG24G), JSPS KAKENHI Grant Number JP18H05439, JST CREST Grant Number JPMJCR1761, the Astrobiology Center of National Institutes of Natural Sciences (NINS) (Grant Number AB031010), the UNAM-DGAPA PAPIIT (BG-101321), the “la Caixa” Foundation (100010434), the European Union Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie (No. 847648, fellowship code LCF/BQ/PI20/11760023), and the Generalitat de Catalunya/CERCA programme. Data were partly collected with the 90-cm telescope at Observatorio de Sierra Nevada (OSN), operated by the Instituto de Astrofísica de Andalucí a (IAA, CSIC). We deeply acknowledge the OSN telescope operators for their very appreciable support.Peer reviewe

Young Exoplanet Transit Initiative follow-up observations of the T Tauri star CVSO 30 with transit-like dips

The T Tauri star CVSO 30, also known as PTFO 8-8695, was studied intensively with ground-based telescopes as well as with satellites over the last decade. It showed a variable light curve with additional repeating planetary transit-like dips every ∼10.8 h. However, these dimming events changed in depth and duration since their discovery and from autumn 2018 on, they were not even present or near the predicted observing times. As reason for the detected dips and their changes within the complex light curve, e.g. a disintegrating planet, a circumstellar dust clump, stellar spots, possible multiplicity, and orbiting clouds at a Keplerian co-rotating radius were discussed and are still under debate. In this paper, we present additional optical monitoring of CVSO 30 with the meter class telescopes of the Young Exoplanet Transit Initiative in Asia and Europe over the last 7 yr and characterize CVSO 30 with the new Early Data Release 3 of the European Space Agency-Gaia mission. As a result, we describe the evolution of the dimming events in the optical wavelength range since 2014 and present explanatory approaches for the observed variabilities. We conclude that orbiting clouds of gas at a Keplerian co-rotating radius are the most promising scenario to explain most changes in CVSO 30’s light curve. © 2022 The Author(s).This work is based on observations obtained with telescopes of the University Observatory Jena, operated by the Astrophysical Institute of the Friedrich-Schiller-Universität Jena. We thank B. Baghdasaryan, N. Belko, S. Buder, M. Dadalauri, M. Geymeier, H. Gilbert, A. Gonzalez, F. Hildebrandt, H. Keppler, O. Lux, S. Masda, P. Protte, J. Trautmann, A. Trepanowski, and S. Schlagenhauf, who have been involved in some observations of this project, obtained at the University Observatory Jena. This research was partly based on data obtained at the 1.5 m telescope of the Sierra Nevada Observatory (Spain), which is operated by the Consejo Superior de Investigaciones Científicas (CSIC) through the Instituto de Astrofísica de Andalucía. We thank J.F. Aceituno and V. Casanova for their help with the observations. This publication is partly based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 090.C-0448(A). RB, RN, and MM acknowledge the support of the DFG priority programme SPP 1992 ‘Exploring the Diversity of Extrasolar Planets’ in projects NE 515/58-1 and MU 2695/27-1. We acknowledge financial support from the Spanish Agencia Estatal de Investigación of the Ministerio de Ciencia, Innovación y Universidades and the ERDF through projects PID2019-109522GB-C52 and AYA2016-79425-C3-3-P, and the Centre of Excellence ‘Severo Ochoa’ award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709). We thank R. Errmann for developing and providing the photometry routine ‘AUTOMAT.PY’ and also C. Broeg for his program ‘PHOTOMETRY’. This publication makes use of data products of the SIMBAD and VizieR data bases, operated at CDS, Strasbourg, France. We also thank the Gaia Data Processing and Analysis Consortium of the ESA for processing and providing the data of the Gaia mission. We thank the MAST portal for providing the TESS photometric results and the MESA Isochrones & Stellar Tracks website for the bolometric correction tables.Peer reviewe

On the Measurement of Intermediate Inequality: A Dominance Criterion for a Ray-Invariant Notion

This paper introduces a unit-consistent Lorenz dominance criterion that allows ranking income distributions according to centrist measures a` la Seidl and Pfingsten (1997). In doing so, it defines α-Lorenz curves that generalize the absolute Lorenz curve. These curves allow implementing unanimous rankings for a broad set of centrist inequality notions, whereas they become closer and closer to the absolute curve when α approaches equity. In addition, this paper provides an empirical illustration of these tools using Australian income data. The results suggest that despite the reduction of relative inequality for Australian-born people between 1999 and 2003, their inequality increased for most centrist value judgments

13C=18O/15N isotope dependence of the amide-I/II 2D IR cross peaks for the fully extended peptides

We have used a combination of 2D IR spectroscopy with 13C=18O labeled amide-I and 15N-labeled amide-II modes to reveal how vibrational coupling between labeled peptide units depends on secondary structure. Linear and 2D IR measurements and simulations of Cα,α-diethylglycine homotetrapeptide show that this compound adopts the fully extended (2.05-helical) conformation in CDCl3, consistent with previous work on the Ac-capped peptide. The amide-I/II cross peaks of isotopomers exhibit only a marginal isotope frequency shift between labeled modes that are separated by two peptide units, indicating a very weak coupling. This result is in sharp contrast with a large cross-peak shift observed in 310-helical peptides, in which the labeled amide-I and -II modes are connected through an inter-residue C=O···H-N hydrogen bond. The discovered 3D-structural dependence indicates that the 13C=18O/15N labeled amide-I/II cross peaks can distinguish the formation of a single 310-helical turn from the fully extended polypeptide chain and increase the versatility of 2D IR spectroscopy as a conformational analysis tool of biomolecules

Model Peptide Aggregates: the Role of Aromatic Interactions and Conformational Aspects

none5The aggregation propensities of two Ala-based pentapeptides [Py-CH2-CO-(L-Ala)5-OtBu (A5P) and Py-CH2-CO-(L-Ala)3- Aib-L-Ala-OtBu (A3UAP)], both functionalized with a pyrene (Py) aromatic chromophore at the N-terminus, have been investigated in methanol/water solvent mixtures by optical spectroscopies and in dried conditions by atomic force microscopy.noneM. Caruso;G. Ballano;F. Formaggio;C. Toniolo;M. VenanziM., Caruso; G., Ballano; Formaggio, Fernando; Toniolo, Claudio; M., Venanz

13C=18O/15N isotope dependence of the amide-I/II 2D IR cross peaks for the fully extended peptides

We have used a combination of 2D IR spectroscopy with 13C=18O labeled amide-I and 15N-labeled amide-II modes to reveal how vibrational coupling between labeled peptide units depends on secondary structure. Linear and 2D IR measurements and simulations of Cα,α-diethylglycine homotetrapeptide show that this compound adopts the fully extended (2.05-helical) conformation in CDCl3, consistent with previous work on the Ac-capped peptide. The amide-I/II cross peaks of isotopomers exhibit only a marginal isotope frequency shift between labeled modes that are separated by two peptide units, indicating a very weak coupling. This result is in sharp contrast with a large cross-peak shift observed in 310-helical peptides, in which the labeled amide-I and -II modes are connected through an inter-residue C=O···H-N hydrogen bond. The discovered 3D-structural dependence indicates that the 13C=18O/15N labeled amide-I/II cross peaks can distinguish the formation of a single 310-helical turn from the fully extended polypeptide chain and increase the versatility of 2D IR spectroscopy as a conformational analysis tool of biomolecules