keyword
MENU ▼
Read by QxMD icon Read
search

l-tyrosine

keyword
https://www.readbyqxmd.com/read/29447970/development-of-a-new-paper-based-nano-biosensor-based-on-the-co-catalytic-effect-of-tyrosinase-from-banana-peel-tissue-musa-cavendish-and-functionalized-silica-nanoparticles-for-voltammetric-determination-of-l-tyrosine
#1
Mohadeseh Rahimi-Mohseni, Jahan Bakhsh Raoof, Reza Ojani, Tahereh A Aghajanzadeh, Ayemeh Bagheri Hashkavayi
A new and facile method for electrochemical determination of L-tyrosine was designed. Tyrosinase from banana peel tissue was immobilized at fiber matrices of the paper disc via physical adsorption. The mediator potassium hexacyanoferrate and 3-mercaptopropyl trimethoxysilane-functionalized silica nanoparticles were added to the paper disc, respectively. The modified paper disc was placed on the top of the graphite screen printed electrode and electrochemical characterization of this biosensor was studied by cyclic voltammetry and electrochemical impedance spectroscopy methods...
February 12, 2018: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/29433005/cytotoxic-activity-and-structural-features-of-ru-ii-phosphine-amino-acid-complexes
#2
Edjane R Dos Santos, Angelica E Graminha, Mario S Schultz, Isabel Correia, Heloisa S Selistre-de-Araújo, Rodrigo S Corrêa, Javier Ellena, Elisângela de Paula S Lacerda, João Costa Pessoa, Alzir A Batista
Thirteen new ruthenium amino acid complexes were synthesized and characterized. They were obtained by the reaction of α-amino acids (AA) with [RuCl2(P-P)(N-N)], where P-P=1,4-bis(diphenylphosphino)butane (dppb) or 1,3-bis(diphenylphosphino)propane (dppp) and N-N=4,4'-dimethyl-2,2'-bipyridine (4'-Mebipy), 5,5'-dimethyl-2,2'-bipyridine (5'-Mebipy) or 4,4'-Methoxy-2-2'-bipyridine (4'-MeObipy). This afforded a family of complexes formulated as [Ru(AA-H)(P-P)(N-N)]PF6, where AA=glycine (Gly), L-alanine (Ala), L-valine (Val), L-tyrosine (Tyr), L-tryptophan (Trp), L-histidine (His) and L-methionine (Met)...
December 23, 2017: Journal of Inorganic Biochemistry
https://www.readbyqxmd.com/read/29417439/antioxidants-reverse-the-changes-in-the-cholinergic-system-caused-by-l-tyrosine-administration-in-rats
#3
Lara M Gomes, Giselli Scaini, Milena Carvalho-Silva, Maria L Gomes, Fernanda Malgarin, Luiza W Kist, Maurício R Bogo, Eduardo Pacheco Rico, Alexandra I Zugno, Pedro F P Deroza, Gislaine Z Réus, Airam B de Moura, João Quevedo, Gustavo C Ferreira, Patrícia F Schuck, Emilio L Streck
Tyrosinemia type II is an inborn error of metabolism caused by a deficiency in the activity of the enzyme tyrosine aminotransferase, leading to tyrosine accumulation in the body. Although the mechanisms involved are still poorly understood, several studies have showed that higher levels of tyrosine are related to oxidative stress and therefore may affect the cholinergic system. Thus, the aim of this study was to investigate the effects of chronic administration of L-tyrosine on choline acetyltransferase activity (ChAT) and acetylcholinesterase (AChE) in the brain of rats...
February 7, 2018: Neurotoxicity Research
https://www.readbyqxmd.com/read/29413752/development-of-radioiodine-labeled-acetaminophen-for-specific-high-contrast-imaging-of-malignant-melanoma
#4
Wen Jing Zhu, Masato Kobayashi, Kohei Yamada, Kodai Nishi, Kotaro Takahashi, Asuka Mizutani, Ryuichi Nishii, Leo G Flores, Naoto Shikano, Munetaka Kunishima, Keiichi Kawai
INTRODUCTION: Due to its poor prognosis, specific imaging for early detection of malignant melanoma is strongly desired. Although radioiodine-labeled 4-hydroxyphenylcysteamine, which we previously developed, has good affinity for tyrosinase, an enzyme in the melanin metabolic pathway, image contrast of the melanoma:organ ratios is not sufficiently high for detection of primary melanoma and metastases at early injection times. In this study, we developed radioiodine-labeled acetaminophen (I-AP) for specific, high-contrast imaging of malignant melanoma...
January 3, 2018: Nuclear Medicine and Biology
https://www.readbyqxmd.com/read/29412935/chirality-detection-of-amino-acid-enantiomers-by-organic-electrochemical-transistor
#5
Lijun Zhang, Guiheng Wang, Can Xiong, Lei Zheng, Jianbo He, Yunsheng Ding, Hongbo Lu, Guobing Zhang, Kilwon Cho, Longzhen Qiu
Chiral recognition of α-amino acids is attracting increasing interest due to the importance of α-amino acids in protein metabolism as well as in food products and pharmaceuticals. Organic electrochemical transistors (OECTs) with gate electrodes modified with molecularly imprinted polymer (MIP) films were fabricated and successfully used as highly selective and sensitive chiral recognition biosensors for d/l-tryptophan (d/l-Trp) and d/l-tyrosine (d/l-Tyr). The MIP films, which can specifically recognize and has an electrocatalytic effect on the oxidation of Trp and Tyr, together with the amplification function of an OECT, provide a highly sensitive and selective OECT biosensor...
May 15, 2018: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/29370262/metabolic-alterations-in-the-nymphal-instars-of-diaphorina-citri-induced-by-candidatus-liberibacter-asiaticus-the-putative-pathogen-of-huanglongbing
#6
Nabil Killiny, Shelley E Jones
Currently, huanglongbing is the most damaging disease of citrus causing huge economic losses. The disease is caused by the Gram-negative bacterium Candidatus Liberibacter asiaticus (CLas). The pathogen is transmitted in a persistent propagative circulative manner within its vector, the Asian citrus psyllid, Diaphorina citri. Exploring the metabolic alteration in the vector may lead to a better understanding of the nutritional needs of CLas and to designing an artificial medium for culturing the pathogen. It has been shown that the nymphal stages have a greater role in transmission mainly because they feed on plants more actively than adults...
2018: PloS One
https://www.readbyqxmd.com/read/29350728/dual-chain-extension-effect-and-antibacterial-properties-of-biomolecules-interleaved-within-ldh-dispersed-into-pbs-by-in-situ-polymerization
#7
Grazia Totaro, Laura Sisti, Annamaria Celli, Irene Aloisio, Diana Di Gioia, Adam A Marek, Vincent Verney, Fabrice Leroux
Nanocomposites based on poly(butylene succinate) (PBS) and hydrotalcite-type anionic clays (HTs) organo-modified with biomolecules characterized by antibacterial and/or antioxidant activities, such as l-ascorbic acid (ASA), phloretic acid (HPP), l-tyrosine (TYR) and l-tryptophan (TRP), have been prepared by in situ polymerization. From XRD analysis and rheology experiments in a molten polymer state, intercalated HT hybrid platelets acting here as a hybrid filler are found to be well dispersed into polymers while providing a chain extension effect on PBS...
January 19, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29340478/the-long-and-successful-journey-of-electrochemically-active-amino-acids-from-fundamental-adsorption-studies-to-potential-surface-engineering-tools
#8
André H B Dourado, Fabián C Pastrián, Susana I Córdoba DE Torresi
Proteins have been the subject of electrochemical studies. It is possible to apply electrochemical techniques to obtain information about their structure due to the presence of five electroactive amino acids that can be oriented to the outside of the peptidic chain. These amino acids are L-Tryptophan (L-Trp), L-Tyrosine (L-Tyr), L-Histidine (L-His), L-Methionine (L-Met) and L-Cysteine (L-Cys); their electrochemical behavior being subject of extensive research, but it is still controversial. No spectroscopic investigations have been reported on L-Trp, and due to the short life time of the intermediates, ex situ techniques cannot be employed, leading to a never-ending discussion about possible intermediates...
January 11, 2018: Anais da Academia Brasileira de Ciências
https://www.readbyqxmd.com/read/29332193/melanogenesis-inhibitory-activity-of-components-from-salam-leaf-syzygium-polyanthum-extract
#9
Andriyana Setyawati, Kae Hirabayashi, Kosei Yamauchi, Hiroyuki Hattori, Tohru Mitsunaga, Irmanida Batubara, Rudi Heryanto, Hiroshi Hashimoto, Mitsuyuki Hotta
In order to identify a novel whitening agent, the methanol extract of S. polyanthum leaf was focused on by the screening test using nine Indonesian medicinal plants for the inhibition of melanogenesis and tyrosinase activity in B16 melanoma cells. Three novel compounds [(1) 1-(2,3,5-trihydroxy-4-methylphenyl)hexane-1-one, (2) 1-(2,3,5-trihydroxy methylphenyl)octane-1-one, and (3) (4E)-1-(2,3,5-trihydroxy-4-methylphenyl)decan-1-one and one known compound [(4) 1-(2,3,5-trihydroxy-4-methylphenyl)decan-1-one were isolated from the methanol extract...
January 13, 2018: Journal of Natural Medicines
https://www.readbyqxmd.com/read/29327587/conformational-impact-on-amino-acid-surface-%C3%AF-%C3%AF-interactions-on-a-7-7-single-walled-carbon-nanotube-a-molecular-mechanics-approach
#10
Linda Grabill, Andreas Riemann
A study of π-π interactions between a (7,7) single-walled carbon nanotube (SWNT) and three different aromatic amino acids (AAA), namely L-Tyrosine (Tyr), L-Tryptophan (Trp), and L-Phenylalanine (Phe) was conducted with a Molecular Mechanics (MM) approach. For each of the amino acids we investigated the behavior of six different conformers. We examined the impact of the so-called edge effects by testing the parameters of the built-in switching function in MM. We found the optimal SWNT length to be approximately 80Å for the size of the molecules in our conformational studies...
January 12, 2018: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29327126/antipyretic-effect-of-herba-ephedrae-ramulus-cinnamomi-herb-pair-on-yeast-induced-pyrexia-rats-a-metabolomics-study
#11
Xiao-Ming Wang, Wen-Jie Xu, Liang-Kui Xu, Shuai Song, Xue-Feng Xing, Jia-Bo Luo
OBJECTIVE: To investigate the antipyretic mechanism of Herba Ephedrae (Eph)-Ramulus Cinnamomi (RC) herb pair on yeast-induced pyrexia in rats. METHODS: Totally 30 qualifified male SD rats were randomly assigned to the normal control (NC) group, the pyrexia model (model) group, the Eph, RC and Eph-RC treatment groups by a random digital table, 6 rats in each group. Each rat received a 20% aqueous suspension of yeast (10 mL/kg) except the NC group. The 3 treatment groups were administered 8...
January 9, 2018: Chinese Journal of Integrative Medicine
https://www.readbyqxmd.com/read/29317025/electrochemical-sensing-platform-based-on-kelp-derived-hierarchical-meso-macroporous-carbons
#12
Yashuang Hei, Xiqian Li, Xiao Zhou, Jingju Liu, Mimi Sun, Tianze Sha, Cuixing Xu, Wanyi Xue, Xiangjie Bo, Ming Zhou
In this paper, kelp (Laminaria japonica), as a kind of abundant biomass, is used as the precursor for the preparation of kelp-derived hierarchical meso-macroporous carbons (K-dHMMCs) through the carbonization under nitrogen (N2) atmosphere at high temperature. The K-dHMMCs exhibits the unique structure with high specific surface area of 416.02 m2 g-1, large pore volume of 0.24 cm3 g-1, the hierarchical meso-macroporous size distribution centered at 2, 12 and 82 nm and high density of defective sites, enabling K-dHMMCs attractive for the electrocatalysis...
March 20, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29310310/l-tyrosine-polymerization-based-ultrasensitive-multi-analyte-enzymatic-biosensor
#13
Lanjunzi Liu, Xiuzhi Kang, Chao Chen, Heping Zhang, Chenpu Chen, Qingji Xie
Novel amperometric bi-enzyme biosensor based on tyrosinase (Tyr)-catalyzed L-tyrosine polymerization to effectively immobilize Tyr and glucose oxidase (GOx) simultaneously has been developed and is demonstrated to be efficient in monitoring multi-analyte (bisphenol A (BPA), phenol, Cr(III), glucose, and Cr(VI)). For the first time, the polymer from L-tyrosine oxidation (PLT) was utilized to in-situ immobilize biomacromolecules and was demonstrated to be effective in entrapping high-load and high-activity enzymes...
March 1, 2018: Talanta
https://www.readbyqxmd.com/read/29300356/synergistic-promotion-on-tyrosinase-inhibition-by-antioxidants
#14
Yan Wang, Mi-Mi Hao, Ying Sun, Li-Feng Wang, Hao Wang, Yan-Jun Zhang, Hong-Yan Li, Peng-Wei Zhuang, Zhen Yang
When exposed to ultraviolet radiation, the human skin produces profuse reactive oxygen species (ROS), which in turn activate a variety of biological responses. Mounting ROS levels activate tyrosinase by mobilizing α-melanocyte-stimulating hormone in the epidermis and finally stimulates the melanocytes to produce melanin. Meanwhile, the Keap1-Nrf2/ARE pathway, which removes ROS, is activated at increased ROS levels, and antioxidant compounds facilitates the dissociation of Nrf2. In this study, we explored the possible suppressing effects of antioxidant compounds and tyrosine inhibitors on melanin formation and the promotory effects of these compounds on ROS scavenging...
January 4, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29296720/x-ray-crystal-structure-of-plasmin-with-tranexamic-acid-derived-active-site-inhibitors
#15
Ruby H P Law, Guojie Wu, Eleanor W W Leung, Koushi Hidaka, Adam J Quek, Tom T Caradoc-Davies, Devadharshini Jeevarajah, Paul J Conroy, Nigel M Kirby, Raymond S Norton, Yuko Tsuda, James C Whisstock
The zymogen protease plasminogen and its active form plasmin perform key roles in blood clot dissolution, tissue remodeling, cell migration, and bacterial pathogenesis. Dysregulation of the plasminogen/plasmin system results in life-threatening hemorrhagic disorders or thrombotic vascular occlusion. Accordingly, inhibitors of this system are clinically important. Currently, tranexamic acid (TXA), a molecule that prevents plasminogen activation through blocking recruitment to target substrates, is the most widely used inhibitor for the plasminogen/plasmin system in therapeutics...
May 9, 2017: Blood Advances
https://www.readbyqxmd.com/read/29289698/tyrosyl-trna-synthetase-a-potential-kyotorphin-synthetase-in-mammals
#16
Tamotsu Tsukahara, Shuhei Yamagishi, Hiroyuki Neyama, Hiroshi Ueda
Kyotorphin (KTP; L-tyrosyl-L-arginine), an opioid-like analgesic discovered in the bovine brain, is potentially a neuromodulator because of its localization in synaptosomes, the existence of a specific KTP receptor, and the presence of its biosynthetic enzyme in the brain. KTP is formed in the brain from its constituent amino acids, L-tyrosine and L-arginine, by an enzyme termed KTP synthetase. However, the latter has never been identified. We aimed to test the hypothesis that tyrosyl-tRNA synthetase (TyrRS) is also KTP synthetase...
December 28, 2017: Peptides
https://www.readbyqxmd.com/read/29277370/improved-rate-of-substrate-oxidation-catalyzed-by-genetically-engineered-myoglobin
#17
Subhash Chand, Sriparna Ray, Eranda Wanigasekara, Poonam Yadav, Joshua A Crawford, Daniel W Armstrong, Krishnan Rajeshwar, Brad S Pierce
This study showcases the potential of unnatural amino acids to enable non-natural functions when incorporated in the protein scaffold of heme metalloproteins. For this purpose, a genetically-engineered myoglobin (Mb) mutant was created by incorporating redox-active 3-amino-l-tyrosine (NH2Tyr) into its active site, replacing the distal histidine (H64) with NH2Tyr. In peroxide-shunt assays, this variant exhibits an increased rate of turnover for thioanisole and benzaldehyde oxidation as compared to the wild-type (WT) Mb...
December 22, 2017: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/29275040/radiosynthesis-and-modified-quality-control-of-o-2-18f-fluoroethyl-l-tyrosine-18f-fet-for-brain-tumor-imaging
#18
Ibrahim Saber Siddiq, Shoukar Tawfik Atwa, Sayed Ahmed Shama, Magdy Hafez Eltaoudy, Walid Mohamed Omar
O-(2-[18F]fluoroethyl)-L-tyrosine ([18F]FET) is the most promising radio-labeled amino acid tracer for brain tumor imaging due to the limitation of 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) and L-methyl-[11C]methionine (11C-MET). However, it has some limitations in radiosynthesis and related quality control that make it less frequently used in many PET centers, in this study, we report a new modification of [18F]FET production using a commercially available fully automated GRP SCINTOMICS module overcoming some of the existing limitations along with a suggestion of a simplified quality control procedure with special focus placed on enantiomeric and radiochemical purity...
December 13, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29244828/involvement-of-phenoloxidase-in-browning-during-grinding-of-tenebrio-molitor-larvae
#19
Renske H Janssen, Catriona M M Lakemond, Vincenzo Fogliano, Giovanni Renzone, Andrea Scaloni, Jean-Paul Vincken
Insects are investigated as alternative protein source to meet the increasing demand for proteins in the future. Enzymatic browning occurring during grinding of insect and subsequent extraction of proteins can influence the proteins' properties, but it is unclear which enzymes are responsible for this phenomenon. This study was performed on larvae of three commonly used insect species, namely Tenebrio molitor, Alphitobius diaperinus and Hermetia illucens. Oxygen consumption measurements on protein extracts showed activity on L-tyrosine, L-3,4-di-hydroxy-phenylalanine (L-DOPA) and L-dopamine, indicating phenoloxidase as a key player in browning...
2017: PloS One
https://www.readbyqxmd.com/read/29244780/a-practical-method-for-the-preparation-of-18f-labeled-aromatic-amino-acids-from-nucleophilic-18f-fluoride-and-stannyl-precursors-for-electrophilic-radiohalogenation
#20
Fadi Zarrad, Boris D Zlatopolskiy, Philipp Krapf, Johannes Zischler, Bernd Neumaier
In a recent contribution of Scott et al., the substrate scope of Cu-mediated nucleophilic radiofluorination with [18F]KF for the preparation of 18F-labeled arenes was extended to aryl- and vinylstannanes. Based on these findings, the potential of this reaction for the production of clinically relevant positron emission tomography (PET) tracers was investigated. To this end, Cu-mediated radiofluorodestannylation using trimethyl(phenyl)tin as a model substrate was re-evaluated with respect to different reaction parameters...
December 15, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
keyword
keyword
38016
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"