Article
Chemistry, Multidisciplinary
Yiyin Xia, Janet To, Ning-Yu Chan, Side Hu, Heng Tai Liew, Seetharamsing Balamkundu, Xiaohong Zhang, Julien Lescar, Surajit Bhattacharjya, James P. Tam, Chuan-Fa Liu
Summary: This study found that Asn(OH) is an unnatural substrate for PALs, and successfully synthesized a new MMP2 inhibitor cyclic peptide using Asn(OH)-mediated cyclization, with the hydroxamic acid moiety as the key pharmacophore. Several bioactive Asp-containing cyclic peptides were also synthesized using this approach, demonstrating the effectiveness of substrate engineering in expanding the application of PAL ligation in the synthesis of therapeutic cyclic peptides.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Organic
Jose A. C. Delgado, Jose T. M. Correia, Emanuele F. Pissinati, Marcio W. Paixao
Summary: This technology utilizes alkyl radicals to selectively alkylate dehydroalanine, offering a convenient method for the synthesis of unnatural amino acids and late-stage functionalization of pharmaceuticals.
Article
Chemistry, Applied
Alemayehu Gashaw Woldegiorgis, Zhao Han, Xufeng Lin
Summary: An enantioselective synthesis of unnatural pyrazole-based alpha-chiral amino acid derivatives was developed using a chiral spirocyclic phosphoric acid catalyst, with yields ranging from 67-98% and enantioselectivities of 73-99%. The NH2 functionality in the products enables further transformations to a chiral thiourea and a lactam, providing a versatile synthetic route for obtaining tetrasubstituted carbon stereocenters in pyrazole-based alpha-amino acid derivatives.
ADVANCED SYNTHESIS & CATALYSIS
(2022)
Article
Chemistry, Multidisciplinary
Yujun Li, Jie Yang, Xinxin Geng, Pan Tao, Yanling Shen, Zhishan Su, Ke Zheng
Summary: This article presents a single-step radical approach for the modular synthesis of functionally diverse alpha-tertiary amino acids (ATAAs). The synthesis takes place under mild conditions without the use of metals, photocatalysts, or other additives. The method demonstrates broad functional group tolerance and late-stage applicability, as well as gram-scale synthesis via flow chemistry. Mechanistic studies reveal the key intermediate in the reaction.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Yingwei Wang, Li-Fan Deng, Xia Zhang, Ze-Dong Mou, Dawen Niu
Summary: A general approach for making unnatural amino acids from cysteine derivatives was reported, utilizing an intramolecular radical substitution process to generate alkyl radicals. The generated alkyl radicals participated in diverse C-C bond forming events under mild, photocatalytic conditions at room temperature, and could be performed open to air. The utility of these transformations was further demonstrated in the straightforward synthesis of various previously inaccessible unnatural amino acids and peptides.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Organic
Narendra Dinkar Kharat, Chikkagundagal K. Mahesha, Kiran Bajaj, Rajeev Sakhuja
Summary: A Rh(III)-catalyzed [5+2] annulation reaction was performed to successfully synthesize oxepine-mounted tyrosine-based unnatural amino acids by reacting vinyl tyrosines with symmetrical and unsymmetrical internal alkynes. The chemical applicability of this strategy was demonstrated through the stapling of amino acid/peptide-appended alkynes with vinyl tyrosines, as well as the late stage functionalization of tyrosine-containing dipeptides and tripeptides with internal alkynes.
Article
Biochemistry & Molecular Biology
Pamela Moleri, Bryan J. Wilkins
Summary: The utilization of an expanded genetic code and in vivo unnatural amino acid crosslinking has become a reliable system for studying protein-protein interactions. The pBPA crosslinker, activated by low energy radiation, has provided extensive structural and mechanistic data, making it a valuable tool in protein analysis. By combining the expanded genetic code system with UV activation, spatial control and spatiotemporal understanding of protein-protein dynamics can be achieved.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2023)
Article
Chemistry, Applied
Tomer M. Faraggi, Caroline Rouget-Virbel, Juan A. Rincon, Mario Barberis, Carlos Mateos, Susana Garcia-Cerrada, Javier Agejas, Oscar de Frutos, David W. C. MacMillan
Summary: The conversion of serine to optically pure unnatural amino acids can be achieved through a two-step process utilizing a photocatalytic cross-electrophile coupling. This method produces artificial analogues of phenylalanine, tryptophan, and histidine, and is tolerant of a broad range of functionalities. It can also be leveraged for the scalable synthesis of valuable pharmaceutical scaffolds via flow technology.
ORGANIC PROCESS RESEARCH & DEVELOPMENT
(2021)
Article
Chemistry, Multidisciplinary
Wenbing Cao, Xuewen Qin, Yong Wang, Zhen Dai, Xianyin Dai, Haoyu Wang, Weimin Xuan, Yingming Zhang, Yu Liu, Tao Liu
Summary: A general host-guest molecular recognition approach involving modification of protein functional surfaces with genetically encoded unnatural amino acids has been developed in this study, which can reversibly regulate protein function through molecular recognition, providing valuable tools for studying protein functions.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Biochemistry & Molecular Biology
Hannae Lee, Dongchan Kim, Sooin Kim, Hyun Soo Lee
Summary: The study showed that converting UAAs into optically pure forms using two enzymes can increase protein yield in genetic code expansion. This method can be utilized for preparing optically pure UAAs and has broad substrate specificity for structurally diverse UAAs.
Review
Biochemistry & Molecular Biology
Ahmad Abuaisheh, Orwa Aboud
Summary: Gliomas are common primary brain tumors that arise from neuroglial cells or progenitor cells. They can be classified as low-grade or high-grade based on WHO classification. Despite extensive research, high-grade gliomas still have a poor prognosis. Biogenic amines, known for their toxic and carcinogenic properties, have not been fully studied in relation to gliomas. This review aims to investigate the roles of biogenic amines in glioma development, diagnostics, and potential treatments.
FRONTIERS IN BIOSCIENCE-LANDMARK
(2023)
Article
Chemistry, Multidisciplinary
Jun-Liang Zhou, Yun-Qi Liu, Zhan-Kui Sun
Summary: Unnatural amino acids (UAAs) play an important role in organic synthesis and drug discovery, as well as biological studies. However, their direct and simplified synthesis remains challenging. Moreover, current peptide modifications mostly rely on carbon-heteroatom bonds, lacking general methods for peptide modifications via C-C bond construction. To address this, we propose the LADA strategy, which involves selective labeling and activation of cysteine residues, desulfurization to generate carbon-centered radicals, and radical addition to alkenes for C-C bond formation. This one-pot protocol offers advantages such as good functional group tolerance, biocompatible reaction conditions, and retention of stereochemistry. It has been successfully applied for unnatural amino acid synthesis and direct peptide modifications.
SCIENCE CHINA-CHEMISTRY
(2023)
Article
Chemistry, Organic
Andrey Shatskiy, Markus D. Karkas
Summary: Recent progress has been made in accessing unnatural alpha-amino acids through photoredox-mediated synthetic methods with a focus on various decarboxylative radical-based strategies.
Article
Chemistry, Applied
Andrea Varga, Pal Csuka, Orlavanah Sonesouphap, Gergely Banoczi, Monica Ioana Tosa, Gabriel Katona, Zsofia Molnar, Laszlo Csaba Bencze, Laszlo Poppe, Csaba Paizs
Summary: A novel phenylalanine ammonia-lyase (PzaPAL) was identified from the psychrophilic yeast Pseudozyma antarctica, showing significantly different substrate binding pocket compared to known PALs. Recombinant PzaPAL exhibited higher turnover numbers than PcPAL and demonstrated enhanced enantiotope selectivity in both kinetic resolutions and ammonia addition reactions.
Article
Chemistry, Physical
Weidong Lin, Lijun You, Wei Yuan, Chuan He
Summary: A copper-catalyzed asymmetric synthesis method has been developed to efficiently prepare chiral beta-germyl alpha-amino acid derivatives, and mechanistic studies have revealed the reaction process. Subsequent transformations yielded a series of germanium-containing functional molecules with potential utility.
Article
Chemistry, Inorganic & Nuclear
R. Galea, K. Moore
Summary: In this study, the solution of 225Ac was standardized using the TDCR method. The counting efficiencies were calculated to be approximately 500% for the NRC TDCR system. The relative uncertainty for the activity concentration was determined to be 0.25%. The measured half-life of 225Ac was found to be consistent with previous measurements.
APPLIED RADIATION AND ISOTOPES
(2024)
Article
Chemistry, Inorganic & Nuclear
N. C. Ramirez, S. M. Collins
Summary: In this paper, the authors determined the half-life of 68Ga using ionisation chambers measurements and HPGe gamma-ray spectrometry. They reviewed the current literature and identified possible causes of inconsistency within the dataset. The findings suggest that addressing these issues could lead to a significant improvement in future evaluations of the half-life.
APPLIED RADIATION AND ISOTOPES
(2024)
Article
Chemistry, Inorganic & Nuclear
C. P. Mano, C. Chapelle, Der Mesrobian Kabakian, H. Paradis, O. Delaune, L. Patryl
Summary: CEA/DAM is developing new beta-gamma measurement systems to enhance the reliability of the Comprehensive Nuclear Test Ban Treaty's verification regime. A new spectral unmixing algorithm for full-spectrum analysis was tested to improve analysis methods for nuclear activities with low statistics.
APPLIED RADIATION AND ISOTOPES
(2024)
Article
Chemistry, Inorganic & Nuclear
Junyoung Lee, Geunsub Kim, Hyegang Chang, Sangmin Lee, Sung-Joon Ye
Summary: The study applied the convolution/superposition method to calculate the dose distribution of boron neutron capture therapy and compared it with the Monte Carlo method. The results showed that the C/S method has a fast calculation speed and reasonable accuracy.
APPLIED RADIATION AND ISOTOPES
(2024)
Article
Chemistry, Inorganic & Nuclear
Victor H. Elvira, Marie-Christine Lepy, Yves Menesguen, Stephanie Melhem
Summary: In this study, a cryogenic electrical-substitution radiometer was utilized for the primary calibration of monochromatic photon beams at a synchrotron facility, in order to determine the intrinsic efficiency and dead layer thickness of an HPGe detector. This calibration method allowed for the calculation of efficiency up to 55 keV, where the active thickness of the detector is not a determining factor. Geometrical efficiency was also determined through measurements of a radioactive source at various distances.
APPLIED RADIATION AND ISOTOPES
(2024)
Article
Chemistry, Inorganic & Nuclear
Ali Pashazadeh, Hamid Reza Baghani, Mostafa Robatjazi, Prajit Kadavil
Summary: This study investigated the effect of patch source geometric parameters on the depth dose distribution in skin tissue through Monte Carlo simulation. The results showed that increasing the source-to-skin distance, patch thickness, and patch diameter will reduce the depth dose distribution, with the source-to-skin distance having the most significant impact on dose gradient.
APPLIED RADIATION AND ISOTOPES
(2024)
Article
Chemistry, Inorganic & Nuclear
Yueli Song, Fengqun Zhou, Yajuan Hao, Xiaopeng Zhang, Pengfei Ji, Yong Li
Summary: In this study, the cross section values of the 109Ag(n,2n)108mAg reaction at different neutron energies were measured using the activation technique and off-line gamma-ray spectrometry. The results were compared with experimental data, evaluated data from libraries, and theoretical values to validate their accuracy.
APPLIED RADIATION AND ISOTOPES
(2024)
Article
Chemistry, Inorganic & Nuclear
Zhongkai Fan, Tao Hu, Xiangming Cai, Ruomei Xie, Haoxuan Li, Fengdi Qin, Shoukang Qiu, Yanliang Tan, Jian Shan
Summary: The high-precision measurement of Rn-220 is crucial for assessing and preventing thoron radiological hazards. By adding a ZnS(Ag)-coated clapboard, the issue of reduced Rn-220 concentrations due to decreased air pressure can be addressed, leading to improved detection efficiency. Experimental and simulation results provide valuable references for establishing the Rn-220 calibration factor.
APPLIED RADIATION AND ISOTOPES
(2024)
Article
Chemistry, Inorganic & Nuclear
R. Han, Z. Chen, Y. Nie, B. Liu, G. Tian, X. Zhang, F. Shi, H. Sun, Z. Zhang, Y. Ding, X. Ruan, J. Ren, S. Zhang
Summary: The leakage neutron spectra of Lead samples were measured using a TOF technique, and MCNP simulations with different nuclear data libraries showed that JENDL-5.0 and JEFF-3.3 libraries have better agreement with experimental data. Differences in spectra mainly stem from variations in neutron reaction channels across the libraries, with ENDF/B-VIII.0 and CENDL-3.2 libraries being overestimated in certain energy ranges.
APPLIED RADIATION AND ISOTOPES
(2024)
Article
Chemistry, Inorganic & Nuclear
Nissren Tamam, Maryam Al Huwayz, Z. A. Alrowaili, Norah Alwadai, Khadijah Mohammedsaleh Katubi, Mohammed S. Alqahtani, I. O. Olarinoye, M. S. Al-Buriahi
Summary: This study investigates the radiation shielding properties and radiation protection applications of borotellurite glasses. The results show that the addition of TeO2 can enhance the glass's ability to absorb photons and fast neutrons, and effectively suppress photon buildup. These glasses also exhibit exceptional gamma radiation and fast neutron moderating abilities, making them suitable for designing lead-free, transparent, and efficient radiation protection structures.
APPLIED RADIATION AND ISOTOPES
(2024)
Article
Chemistry, Inorganic & Nuclear
S. Chasapoglou, M. Kokkoris, R. Vlastou, M. Diakaki, V. Michalopoulou, A. Kalamara, G. Gkatis, A. Stamatopoulos, M. Axiotis, S. Harissopulos, A. Lagoyannis, M. I. Savva, T. Vasilopoulou, C. Lederer-Woods, N. Patronis, K. Kaperoni
Summary: This study investigated the accuracy and limitations of theoretical corrections in neutron-induced reactions on isotopically enriched Ge targets. Experimental cross-section measurements were conducted on several reactions using Ge-nat and isotopically enriched Ge targets. The results showed that the methodology using isotopically enriched targets provided accurate results without the need for theoretical corrections.
APPLIED RADIATION AND ISOTOPES
(2024)
Article
Chemistry, Inorganic & Nuclear
P. G. Konstantinidis, G. S. Polymeris, E. Tsoutsoumanos, G. Kitis
Summary: This study investigates an altered version of an existing protocol to study the mechanisms and phenomena of stimulated luminescence. The protocol allows for the examination of recombination mechanisms and trapping parameters of the traps, as well as the observation of potential transitions between two different states.
APPLIED RADIATION AND ISOTOPES
(2024)
Article
Chemistry, Inorganic & Nuclear
Quanzhi Yu
Summary: This study obtained the broad neutron spectrum of the Atmospheric Neutron Irradiation Spectrometer (ANIS) through Monte Carlo simulation and provided an analytic expression. By calculating the Single Error Rate (SER) and ratio, the reliability of the ANIS neutron spectrum was evaluated.
APPLIED RADIATION AND ISOTOPES
(2024)
Article
Chemistry, Inorganic & Nuclear
D. Glavic Cindro, M. Korun, T. Petrovic, B. Vodenik, B. Zorko
Summary: In gamma-ray spectrometric measurements, the decision threshold is determined by the observed value of the measurand. However, this dependence restricts its application to measurements with non-expressive indications. To address this issue, a recalculation of the decision thresholds based on the peak widths corresponding to expressive indications is proposed.
APPLIED RADIATION AND ISOTOPES
(2024)