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https://www.readbyqxmd.com/read/29051071/increase-of-bacillus-badius-phenylalanine-dehydrogenase-specificity-towards-phenylalanine-substrate-by-site-directed-mutagenesis
#1
Farzad Yousefi, Farangis Ataei, Seyed Shahriar Arab, Saman Hosseinkhani
Phenylalanine dehydrogenase (PheDH) is a key enzyme in medical diagnostic for determining the amount of phenylalanine to detect phenylketonuria (PKU) disease. However, determination of phenylalanine can be usually disturbed in presence of tyrosine in blood samples. Position N145 of B.sphaericus PheDH, has been previously showed a crucial role in substrate binding, which corresponded by position V144 in B. badius PheDH. In this study, the PheDH of B. badius due to reasonable activity was cloned and subjected to site-directed mutagenesis at mentioned position, followed by kinetic and structural studies to find more exclusive mutants...
October 16, 2017: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/29043400/static-and-dynamic-18-f-fet-pet-for-the-characterization-of-gliomas-defined-by-idh-and-1p-19q-status
#2
Antoine Verger, Gabriele Stoffels, Elena K Bauer, Philipp Lohmann, Tobias Blau, Gereon R Fink, Bernd Neumaier, Nadim J Shah, Karl-Josef Langen, Norbert Galldiks
PURPOSE: The molecular features isocitrate dehydrogenase (IDH) mutation and 1p/19q co-deletion have gained major importance for both glioma typing and prognosis and have, therefore, been integrated in the World Health Organization (WHO) classification in 2016. The aim of this study was to characterize static and dynamic O-(2-(18)F-fluoroethyl)-L-tyrosine ((18)F-FET) PET parameters in gliomas with or without IDH mutation or 1p/19q co-deletion. METHODS: Ninety patients with newly diagnosed and untreated gliomas with a static and dynamic (18)F-FET PET scan prior to evaluation of tumor tissue according to the 2016 WHO classification were identified retrospectively...
October 17, 2017: European Journal of Nuclear Medicine and Molecular Imaging
https://www.readbyqxmd.com/read/29020830/a-novel-biomarker-explaining-the-role-of-oxidative-stress-in-exercise-and-l-tyrosine-supplementation-thiol-disulphide-homeostasis
#3
Yildirim Kayacan, Hayrullah Yazar, Emin Can Kisa, Babak Elmi Ghojebeigloo
The present study aimed to evaluate the relationship between exercise and both l-tyrosine and oxidative stress using thiol/disulphide homeostasis via a novel biomarker in rats. Following the completion of the exercise and l-tyrosine protocol, serum total thiol, native thiol, and disulphide concentrations were determined using a novel automated measurement method. Compared with the control group, serum dynamic disulphide levels were significantly lower in the E group (116.75 ± 10.49; p < .05) and the highest in the LT group (151...
October 11, 2017: Archives of Physiology and Biochemistry
https://www.readbyqxmd.com/read/29017435/expression-purification-and-characterization-of-a-novel-acid-phosphatase-that-displays-protein-tyrosine-phosphatases-activity-from-metarhizium-anisopliae-strain-cqma102
#4
Xue Zhang, Shuiying Yang, Xinqiang Li, Pei Zhu, Enyu Xie, Zhenlun Li
The protein tyrosine phosphatase (PTPase) plays an important role in insect immune system. Our group has purified a type of acid phosphatase that could specifically dephosphorylate trans-Golgi p230 in vitro. In order to study this phosphatase further, we have identified and cloned the phosphatase gene from a locust specific Metarhizium anisopliae Strain CQMa102. The CQMa102 phosphatase was expressed in Pichia pastoris to verify its protease activity. The molecular weight (MW) and the isoelectric point (pI) of the phosphatase were about 85 kDa and 6...
October 11, 2017: Bioscience, Biotechnology, and Biochemistry
https://www.readbyqxmd.com/read/28992332/l-tyrosine-induces-the-production-of-a-pyomelanin-like-pigment-by-the-parasitic-yeast-form-of-histoplasma-capsulatum
#5
Rodrigo Almeida-Paes, Fernando Almeida-Silva, Gabriela Costa Maia Pinto, Marcos de Abreu Almeida, Mauro de Medeiros Muniz, Claudia Vera Pizzini, Gary J Gerfen, Joshua Daniel Nosanchuk, Rosely Maria Zancopé-Oliveira
Melanization of Histoplasma capsulatum remains poorly described, particularly in regards to the forms of melanin produced. In the present study, 30 clinical and environmental H. capsulatum strains were grown in culture media with or without L-tyrosine under conditions that produced either mycelial or yeast forms. Mycelial cultures were not melanized under the studied conditions. However, all strains cultivated under yeast conditions produced a brownish to black soluble pigment compatible with pyomelanin when grew in presence of L-tyrosine...
September 12, 2017: Medical Mycology: Official Publication of the International Society for Human and Animal Mycology
https://www.readbyqxmd.com/read/28990327/the-recent-crystal-structure-of-human-tyrosinase-related-protein-1-hstyrp1-solves-an-old-problem-and-poses-a-new-one
#6
Heinz Decker, Felix Tuczek
Show your metal: l-Tyrosine is converted into the protective antioxidative polymer melanin in a sequence of reactions. In humans, the catalytic pathway starts with the tyrosinase HsTYR and two tyrosinase-related proteins HsTYRP1 and HsTYRP2. All three enzymes have the same active site but the latter two contain two zinc ions instead of copper ions.
October 9, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28990194/relaxation-of-tyrosine-pathway-regulation-underlies-the-evolution-of-betalain-pigmentation-in-caryophyllales
#7
Samuel Lopez-Nieves, Ya Yang, Alfonso Timoneda, Minmin Wang, Tao Feng, Stephen A Smith, Samuel F Brockington, Hiroshi A Maeda
Diverse natural products are synthesized in plants by specialized metabolic enzymes, which are often lineage-specific and derived from gene duplication followed by functional divergence. However, little is known about the contribution of primary metabolism to the evolution of specialized metabolic pathways. Betalain pigments, uniquely found in the plant order Caryophyllales, are synthesized from the aromatic amino acid l-tyrosine (Tyr) and replaced the otherwise ubiquitous phenylalanine-derived anthocyanins...
October 9, 2017: New Phytologist
https://www.readbyqxmd.com/read/28983293/biofilm-formation-and-heat-stress-induce-pyomelanin-production-in-deep-sea-pseudoalteromonas-sp-sm9913
#8
Zhenshun Zeng, Xingsheng Cai, Pengxia Wang, Yunxue Guo, Xiaoxiao Liu, Baiyuan Li, Xiaoxue Wang
Pseudoalteromonas is an important bacterial genus present in various marine habitats. Many strains of this genus are found to be surface colonizers on marine eukaryotes and produce a wide range of pigments. However, the exact physiological role and mechanism of pigmentation were less studied. Pseudoalteromonas sp. SM9913 (SM9913), an non-pigmented strain isolated from the deep-sea sediment, formed attached biofilm at the solid-liquid interface and pellicles at the liquid-air interface at a wide range of temperatures...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28980392/utilizing-18f-fluoroethyl-l-tyrosine-positron-emission-tomography-in-high-grade-glioma-for-radiation-treatment-planning-in-patients-with-contraindications-to-mri
#9
Dasantha T Jaymanne, Sneha Kaushal, David Chan, Geoff Schembri, David Brazier, Dale Bailey, Helen Wheeler, Michael Back
INTRODUCTION: Patients with high grade glioma (HGG) and contraindications to magnetic resonance imaging (MRI) are dependent on contrast-enhanced computerized tomography (CT) scan imaging for radiation therapy (RT) target volume delineation. This study reviews the experience with the utilization of 18F-fluoroethyl-l-tyrosine positron emission tomography (FET-PET) to define residual disease post craniotomy and optimize RT planning. METHODS: Patients with HGG and a contraindication to MRI managed with radiation therapy between 2007 and 2015 were identified...
October 5, 2017: Journal of Medical Imaging and Radiation Oncology
https://www.readbyqxmd.com/read/28963347/evolution-of-allosteric-regulation-in%C3%A2-chorismate-mutases-from-early-plants
#10
Kourtney Kroll, Cynthia K Holland, Courtney M Starks, Joseph M Jez
Plants, fungi, and bacteria synthesize the aromatic amino acids:  L -phenylalanine,  L -tyrosine, and  L -tryptophan. Chorismate mutase catalyzes the branch point reaction of phenylalanine and tyrosine biosynthesis to generate prephenate. In  Arabidopsis thaliana , there are two plastid-localized chorismate mutases that are allosterically regulated (AtCM1 and AtCM3) and one cytosolic isoform (AtCM2) that is unregulated. Previous analysis of plant chorismate mutases suggested that the enzymes from early plants (i...
September 28, 2017: Biochemical Journal
https://www.readbyqxmd.com/read/28960770/determination-of-alkyl-donor-promiscuity-of-tyrosine-o-prenyltransferase-sird-from-leptosphaeria-maculans
#11
Chandrasekhar Bandari, Erin M Scull, Johanna M Masterson, Rachel H Q Tran, Steven B Foster, Kenneth M Nicholas, Shanteri Singh
Natural product prenyltransferases are known to display relaxed acceptor substrate specificity. While recent studies using a small set of unnatural alkyl donors reveal prenyltransferases to be flexible towards their alkyl donors, the scope of alkyl donor specificity remains poorly understood. Towards this goal, we report the synthesis of 20 unnatural alkyl pyrophosphate donors and assessment of the tyrosine O-prenyltransferase SirD catalyzed reaction with synthetic unnatural alkyl pyrophosphate analogues. This study demonstrates SirD to utilize 16 out of 21 alkyl pyrophosphate analogues (including natural donor) in catalyzing mostly O-alkylation of L-tyrosine...
September 27, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28960638/total-synthesis-of-spiroleucettadine
#12
Bill C Hawkins, Richard Lamb, Nicholas Aberle, Nigel Lucas, Guillaume Lessene
Amongst an intriguing number of new alkaloids isolated from the Leucetta sp. sponge in 2004 was spiroleucettadine, which displayed unique structural features on a restricted scaffold: a trans-fused 5,5-bicyclic ring system together with an amino-hemiketal moiety. Attempts at synthesizing the initially proposed structure failed raising questions as to its veracity and as a result structure revision ensued in 2008; no successful synthetic approach has been reported to date. Herein, we describe the first enantiospecific total synthesis of (-)-spiroleucettadine using a highly efficient biomimetic approach starting from L-tyrosine...
September 27, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28902505/activation-mechanism-of-the-streptomyces-tyrosinase-assisted-by-the-caddie-protein
#13
Yasuyuki Matoba, Shogo Kihara, Yoshimi Muraki, Naohiko Bando, Hironari Yoshitsu, Teruo Kuroda, Miyuki Sakaguchi, Kure'e Kayama, Hulin Tai, Shun Hirota, Takashi Ogura, Masanori Sugiyama
Tyrosinase (EC 1.14.18.1), which possesses two copper ions at the active center, catalyzes a rate-limiting reaction of melanogenesis, that is, the conversion of a phenol to the corresponding ortho-quinone. The enzyme from the genus Streptomyces is generated as a complex with a "caddie" protein that assists the transport of two copper ions into the active center. In this complex, the Tyr(98) residue in the caddie protein was found to be accommodated in the pocket of the active center of tyrosinase, probably in a manner similar to that of l-tyrosine as a genuine substrate of tyrosinase...
October 17, 2017: Biochemistry
https://www.readbyqxmd.com/read/28902455/synthesis-of-2-amino-3-cyanopyridine-derivatives-and-investigation-of-their-carbonic-anhydrase-inhibition-effects
#14
Aliye Altundas, Berna Gül, Murat Çankaya, Ali Atasever, İlhami Gülçin
The conversion of carbon dioxide (CO2 ) and bicarbonate (HCO3(-) ) to each other is very important for living metabolism. Carbonic anhydrase (CA, E.C.4.2.1.1), a metalloenzyme familly, catalyzes the interconversion of these ions (CO2 and HCO3(-) ) and are very common in living organisms. In this study, a series of novel 2-amino-3-cyanopyridines supported with some functional groups was synthesized and tested as potential inhibition effects against both cytosolic human CA I and II isoenzymes (hCA I and II) using by Sepharose-4B-l-tyrosine-sulfanilamide affinity chromatography...
September 13, 2017: Journal of Biochemical and Molecular Toxicology
https://www.readbyqxmd.com/read/28884633/oxidative-removal-of-aromatic-amino-acids-by-manganese-dioxide-kinetic-modeling-and-effect-of-co-solutes
#15
Yong Chen, Jing Su, Lu Liu, Yiling Zhou, Jiaolan Zuo, Zongping Wang, Tao Tao
The degradation of aromatic amino acids including L-tryptophan, L-tyrosine and L-phenylalanine by δ-MnO2 was investigated. L-tryptophan and L-tyrosine underwent rapid oxidative degradation in the δ-MnO2 suspension solution. In contrast, L-phenylalanine was not oxidized by δ-MnO2. The degradation of L-tryptophan was faster than that of L-tyrosine. The oxidation rates of amino acids increased with increasing concentration of δ-MnO2. The increase of concentrations of substrates and pH disfavored the degradation...
September 8, 2017: Environmental Technology
https://www.readbyqxmd.com/read/28880730/tyrosine-derived-novel-antimicrobial-hydantoin-polymers-synthesis-and-evaluation-of-anti-bacterial-activities
#16
Vasanthan Ravichandran, Rajani Kant Rai, Venkitasamay Kesavan, A Jayakrishnan
A new approach for the design and synthesis of cyclic N-halamine polymers having anti-bacterial activity based on a vinyl derivative of tyrosine-derived hydantoin is reported. The synthesis of N-halamine polymers generally involves the chemical modification of 5,5'-disubstituted hydantoin to introduce polymerizable vinyl moieties thereby restricting the halogen capture only on the amide nitrogen. Here we show the possibility of synthesizing vinyl monomers of N-halamine from α-amino acids wherein both the amide and imide nitrogens are available for halogen capture...
September 7, 2017: Journal of Biomaterials Science. Polymer Edition
https://www.readbyqxmd.com/read/28866736/peroxynitrite-scavenging-by-campylobacter-jejuni-truncated-hemoglobin-p
#17
Paolo Ascenzi, Alessandra Pesce
Truncated hemoglobins (trHb) are present in protozoa, cyanobacteria, nemertean, bacteria, algae, and plants. They are characterized by the 2-on-2 topology and are ordered in four phylogenetic groups (I or N, II or O, III or P, and IV or Q). Several functions have been attributed to trHbs including the inactivation of reactive nitrogen and oxygen species, permitting the survival of microorganisms in the host. Here, the kinetics of peroxynitrite scavenging by ferric Campylobacter jejuni truncated hemoglobin P [i...
September 2, 2017: Journal of Biological Inorganic Chemistry: JBIC
https://www.readbyqxmd.com/read/28837636/tetrodotoxin-insensitive-electrical-field-stimulation-induced-contractions-on-crotalus-durissus-terrificus-corpus-cavernosum
#18
Rafael Campos, Fabíola Z Mónica, Renata Lopes Rodrigues, Julio Alejandro Rojas-Moscoso, Ronilson Agnaldo Moreno, José Carlos Cogo, Marco Antonio de Oliveira, Edson Antunes, Gilberto De Nucci
Reptiles are the first amniotes to develop an intromitent penis, however until now the mechanisms involved in the electrical field stimulation-induced contraction on corpora cavernosa isolated from Crotalus durissus terrificus were not investigated. Crotalus and rabbit corpora cavernosa were mounted in 10 mL organ baths for isometric tension recording. Electrical field stimulation (EFS)-induced contractions were performed in presence/absence of phentolamine (10 μM), guanethidine (30 μM), tetrodotoxin (1 μM and 1mM), A-803467 (10 μM), 3-iodo-L-Tyrosine (1 mM), salsolinol (3 μM) and a modified Krebs solution (equimolar substitution of NaCl by N-methyl-D-glucamine)...
2017: PloS One
https://www.readbyqxmd.com/read/28831534/comparison-of-18-f-fet-pet-and-perfusion-weighted-mri-for-glioma-grading-a-hybrid-pet-mr-study
#19
Antoine Verger, Christian P Filss, Philipp Lohmann, Gabriele Stoffels, Michael Sabel, Hans J Wittsack, Elena Rota Kops, Norbert Galldiks, Gereon R Fink, Nadim J Shah, Karl-Josef Langen
PURPOSE: Both perfusion-weighted MR imaging (PWI) and O-(2-(18)F-fluoroethyl)-L-tyrosine PET ((18)F-FET) provide grading information in cerebral gliomas. The aim of this study was to compare the diagnostic value of (18)F-FET PET and PWI for tumor grading in a series of patients with newly diagnosed, untreated gliomas using an integrated PET/MR scanner. METHODS: Seventy-two patients with untreated gliomas [22 low-grade gliomas (LGG), and 50 high-grade gliomas (HGG)] were investigated with (18)F-FET PET and PWI using a hybrid PET/MR scanner...
August 22, 2017: European Journal of Nuclear Medicine and Molecular Imaging
https://www.readbyqxmd.com/read/28819265/the-chemical-signatures-underlying-host-plant-discrimination-by-aphids
#20
David P Hopkins, Duncan D Cameron, Roger K Butlin
The diversity of phytophagous insects is largely attributable to speciation involving shifts between host plants. These shifts are mediated by the close interaction between insects and plant metabolites. However, there has been limited progress in understanding the chemical signatures that underlie host preferences. We use the pea aphid (Acyrthosiphon pisum) to address this problem. Host-associated races of pea aphid discriminate between plant species in race-specific ways. We combined metabolomic profiling of multiple plant species with behavioural tests on two A...
August 17, 2017: Scientific Reports
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