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https://www.readbyqxmd.com/read/27910839/accurate-hydrogen-parameters-for-the-amino-acid-l-leucine
#1
Jack Binns, Simon Parsons, Garry J McIntyre
The structure of the primary amino acid L-leucine has been determined for the first time by neutron diffraction. This was made possible by the use of modern neutron Laue diffraction to overcome the previously prohibitive effects of crystal size and quality. The packing of the structure into hydrophobic and hydrophilic layers is explained by the intermolecular interaction energies calculated using the PIXEL method. Variable-temperature data collections confirmed the absence of phase transitions between 120 and 300 K in the single-crystal form...
December 1, 2016: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/27875537/effect-of-l-tryptophan-and-l-leucine-on-gut-hormone-secretion-appetite-feelings-and-gastric-emptying-rates-in-lean-and-non-diabetic-obese-participants-a-randomized-double-blind-parallel-group-trial
#2
Anne Christin Meyer-Gerspach, Simon Häfliger, Julian Meili, Alison Doody, Jens F Rehfeld, Jürgen Drewe, Christoph Beglinger, Bettina Wölnerhanssen
BACKGROUND/OBJECTIVES: Gut hormones such as cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1) play a role as satiation factors. Strategies to enhance satiation peptide secretion could provide a therapeutic approach for obesity. Carbohydrates and lipids have been extensively investigated in relation to peptide release. In contrast, the role of proteins or amino acids is less clear. Our aim was to compare the effects of the amino acids L-tryptophan (L-trp) and L-leucine (L-leu) separately on gastric emptying and gut peptide secretion...
2016: PloS One
https://www.readbyqxmd.com/read/27873181/inhalable-ipratropium-bromide-particle-engineering-with-multicriteria-optimization
#3
Bhavani Prasad Vinjamuri, Rahul V Haware, William C Stagner
Spray-dried ipratropium bromide (IPB) microspheres for oral inhalation were engineered using Quality by Design. The interrogation of material properties, process parameters, and critical product quality attributes interplay enabled rational product design. A 2(7-3) screening design exhibited the Maillard reaction between L-leucine (LL) and lactose at studied outlet temperatures (OT) >130°C. A response surface custom design was used in conjunction with multicriteria optimization to determine the operating design space to achieve inhalable microparticles...
November 21, 2016: AAPS PharmSciTech
https://www.readbyqxmd.com/read/27872960/branched-chain-amino-acids
#4
Keisuke Yamamoto, Atsunari Tsuchisaka, Hideaki Yukawa
Branched-chain amino acids (BCAAs), viz., L-isoleucine, L-leucine, and L-valine, are essential amino acids that cannot be synthesized in higher organisms and are important nutrition for humans as well as livestock. They are also valued as synthetic intermediates for pharmaceuticals. Therefore, the demand for BCAAs in the feed and pharmaceutical industries is increasing continuously. Traditional industrial fermentative production of BCAAs was performed using microorganisms isolated by random mutagenesis. A collection of these classical strains was also scientifically useful to clarify the details of the BCAA biosynthetic pathways, which are tightly regulated by feedback inhibition and transcriptional attenuation...
November 22, 2016: Advances in Biochemical Engineering/biotechnology
https://www.readbyqxmd.com/read/27845719/electrochemical-aptatoxisensor-responses-on-nanocomposites-containing-electro-deposited-silver-nanoparticles-on-poly-propyleneimine-dendrimer-for-the-detection-of-microcystin-lr-in-freshwater
#5
Mawethu P Bilibana, Avril R Williams, Candice Rassie, Christopher E Sunday, Hlamulo Makelane, Lindsay Wilson, Nomaphelo Ntshongontshi, Abongile N Jijana, Milua Masikini, Priscilla G L Baker, Emmanuel I Iwuoha
A sensitive and reagentless electrochemical aptatoxisensor was developed on cobalt (II) salicylaldiimine metallodendrimer (SDD-Co(II)) doped with electro-synthesized silver nanoparticles (AgNPs) for microcystin-LR (L, l-leucine; R, l-arginine), or MC-LR, detection in the nanomolar range. The GCE|SDD-Co(II)|AgNPs aptatoxisensor was fabricated with 5' thiolated aptamer through self-assembly on the modified surface of the glassy carbon electrode (GCE) and the electronic response was measured using cyclic voltammetry (CV)...
November 11, 2016: Sensors
https://www.readbyqxmd.com/read/27806640/novel-propanamide-analogue-and-antiproliferative-diketopiperazines-from-mangrove-streptomyces-sp-q24
#6
Xuewei Ye, Weiyun Chai, Xiao-Yuan Lian, Zhizhen Zhang
A new propanamide analogue (1), along with one known alkaloid (2) and four known diketopiperazines (3-6), was isolated from a cultured broth of the actinomycete Streptomyces sp. Q24 that was obtained from a sample of mangrove soil. The structures of these isolates were characterised as 3-acetylamino-N-2-thienyl-propanamide (1), N-acetyltryptamine (2), cyclo-(l-phenylalanine-l-4-hydroxyproline) (3), cyclo-(l-leucine-l-4-hydroxyproline) (4), cyclo-(l-phenylalanine-d-4-hydroxyproline) (5) and cyclo-(l-leucine-l-proline) (6) based on their NMR and HRESIMS data as well as optical rotation...
November 3, 2016: Natural Product Research
https://www.readbyqxmd.com/read/27760995/differential-effects-of-l-tryptophan-and-l-leucine-administration-on-brain-resting-state-functional-networks-and-plasma-hormone-levels
#7
Davide Zanchi, Anne Christin Meyer-Gerspach, Claudia Suenderhauf, Katharina Janach, Carel W le Roux, Sven Haller, Jürgen Drewe, Christoph Beglinger, Bettina K Wölnerhanssen, Stefan Borgwardt
Depending on their protein content, single meals can rapidly influence the uptake of amino acids into the brain and thereby modify brain functions. The current study investigates the effects of two different amino acids on the human gut-brain system, using a multimodal approach, integrating physiological and neuroimaging data. In a randomized, placebo-controlled trial, L-tryptophan, L-leucine, glucose and water were administered directly into the gut of 20 healthy subjects. Functional MRI (fMRI) in a resting state paradigm (RS), combined with the assessment of insulin and glucose blood concentration, was performed before and after treatment...
October 20, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27743105/investigating-on-the-correlation-between-some-biological-activities-of-marine-sponge-associated-bacteria-extracts-and-isolated-diketopiperazines
#8
Faten K Abd El-Hady, Walid Fayad, Carmine Iodice, Zeinab A El-Shahid, Mohamed S Abdel-Aziz, Egle Crudele, Giuseppina Tommonaro
Marine organisms have been considered as the richest sources of novel bioactive metabolites, which can be used for pharmaceutical purposes. In the last years, the interest for marine microorganisms has grown for their enormous biodiversity and for the evidence that many novel compounds isolated from marine invertebrates are really synthesized by their associated bacteria. Nevertheless, the discovery of a chemical communication Quorum sensing (QS) between bacterial cells and between bacteria and host has gained the researchers to expand the aim of their study toward the role of bacteria associated with marine invertebrates, such as marine sponge...
October 14, 2016: Current Microbiology
https://www.readbyqxmd.com/read/27723140/synthesis-of-fluorescent-gelators-and-direct-observation-of-gelation-with-a-fluorescence-microscope
#9
Kenji Hanabusa, Takuya Ueda, Shingo Takata, Masahiro Suzuki
Fluorescein-, benzothiazole-, quinoline-, stilbene-, and carbazole-containing fluorescent gelators have been synthesized by connecting gelation-driving segments, including l-isoleucine, l-valine, l-phenylalanine, l-leucine residue, cyclo(l-asparaginyl-l-phenylalanyl), and trans-(1R,2R)-diaminocyclohexane. The emission behaviors of the gelators were investigated, and their gelation abilities studied against 15 solvents. The minimum gel concentration, variable-temperature spectroscopy, transmission electron microscopy, scanning electron microscopy, fluorescence microscopy (FM), and confocal laser scanning microscopy (CLSM) were used to characterize gelation...
November 14, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27716121/leucine-rich-diet-alters-the-1-h-nmr-based-metabolomic-profile-without-changing-the-walker-256-tumour-mass-in-rats
#10
Laís Rosa Viana, Rafael Canevarolo, Anna Caroline Perina Luiz, Raquel Frias Soares, Camila Lubaczeuski, Ana Carolina de Mattos Zeri, Maria Cristina Cintra Gomes-Marcondes
BACKGROUND: Cachexia is one of the most important causes of cancer-related death. Supplementation with branched-chain amino acids, particularly leucine, has been used to minimise loss of muscle tissue, although few studies have examined the effect of this type of nutritional supplementation on the metabolism of the tumour-bearing host. Therefore, the present study evaluated whether a leucine-rich diet affects metabolomic derangements in serum and tumour tissues in tumour-bearing Walker-256 rats (providing an experimental model of cachexia)...
October 3, 2016: BMC Cancer
https://www.readbyqxmd.com/read/27716065/cyp79d-enzymes-contribute-to-jasmonic-acid-induced-formation-of-aldoximes-and-other-nitrogenous-volatiles-in-two-erythroxylum-species
#11
Katrin Luck, Jan Jirschitzka, Sandra Irmisch, Meret Huber, Jonathan Gershenzon, Tobias G Köllner
BACKGROUND: Amino acid-derived aldoximes and nitriles play important roles in plant defence. They are well-known as precursors for constitutive defence compounds such as cyanogenic glucosides and glucosinolates, but are also released as volatiles after insect feeding. Cytochrome P450 monooxygenases (CYP) of the CYP79 family catalyze the formation of aldoximes from the corresponding amino acids. However, the majority of CYP79s characterized so far are involved in cyanogenic glucoside or glucosinolate biosynthesis and only a few have been reported to be responsible for nitrogenous volatile production...
October 4, 2016: BMC Plant Biology
https://www.readbyqxmd.com/read/27714346/structural-behaviour-and-gene-delivery-in-complexes-formed-between-dna-and-arginine-containing-peptide-amphiphiles
#12
Emerson R Silva, Gary Cooney, Ian W Hamley, Wendel A Alves, Shannon Lee, Brendan F O'Connor, Mehedi Reza, Janne Ruokolainen, Dermot Walls
We describe in depth the structure of complexes formed between DNA and two classes of arginine-containing peptide amphiphiles, namely, the lipopeptide PRW-C16 (P = proline, R = arginine, W = tryptophan, C16 = C16 : 0 alkyl chain) and the bolaamphiphile RFL4FR (R = arginine, F = phenylalanine, L = leucine). A combination of X-ray and neutron scattering provided unprecedented insights into the local structure of these complexes. Lipopeptide-based complexes self-assembled into layered structures with large-scale fractal features, hosting DNA in the interstices...
November 16, 2016: Soft Matter
https://www.readbyqxmd.com/read/27667645/in-situ-ratiometric-quantitative-tracing-of-intracellular-leucine-aminopeptidase-activity-via-an-activatable-near-infrared-fluorescent-probe
#13
Kaizhi Gu, Yajing Liu, Zhiqian Guo, Cheng Lian, Chenxu Yan, Ping Shi, He Tian, Wei-Hong Zhu
Leucine aminopeptidase (LAP), one of the important proteolytic enzymes, is intertwined with the progress of many pathological disorders as a well-defined biomarker. To explore fluorescent aminopeptidase probe for quantitative detection of LAP distribution and dynamic changes, herein we report a LAP-targeting near-infrared (NIR) fluorescent probe (DCM-Leu) for ratiometric quantitative trapping of LAP activity in different kinds of living cells. DCM-Leu is composed of a NIR-emitting fluorophore (DCM) as a reporter and l-leucine as a triggered moiety, which are linked together by an amide bond specific for LAP cleavage...
October 3, 2016: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/27665128/single-step-coprocessing-of-cohesive-powder-via-mechanical-dry-coating-for-direct-tablet-compression
#14
Li Qu, Peter J Stewart, Karen P Hapgood, Satu Lakio, David A V Morton, Qi Tony Zhou
This study aims at testing the feasibility of a single-step coating process to produce a powder formulation of active and inactive ingredients for direct compression. A cohesive ibuprofen powder was coprocessed with a coating material, a binder (polyvinylpyrrolidone K25), and a superdisintegrant (crospovidone). Magnesium stearate (MgSt), l-leucine, and silica were selected as coating materials (1% w/w). A coprocessed powder without any coating material was employed as a control. Coating with MgSt, l-leucine, or silica produced significantly improved powder flow in comparison to the control batch...
September 21, 2016: Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/27617997/synthesis-and-cytotoxic-activity-on-human-cancer-cells-of-novel-isoquinolinequinone-amino-acid-derivatives
#15
Jaime A Valderrama, Virginia Delgado, Sandra Sepúlveda, Julio Benites, Cristina Theoduloz, Pedro Buc Calderon, Giulio G Muccioli
A variety of aminoisoquinoline-5,8-quinones bearing α-amino acids moieties were synthesized from 3-methyl-4-methoxycarbonylisoquinoline-5,8-quinone and diverse l- and d-α-amino acid methyl esters. The members of the series were evaluated for their cytotoxic activity against normal and cancer cell lines by using the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay. From the current investigation, structure-activity relationships demonstrate that the location and structure of the amino acid fragment plays a significant role in the cytotoxic effects...
2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/27604893/aerosolization-drug-permeation-and-cellular-interaction-of-dry-powder-pulmonary-formulations-of-corticosteroids-with-hydroxypropyl-%C3%AE-cyclodextrin-as-a-solubilizer
#16
Ville Vartiainen, Luis M Bimbo, Jouni Hirvonen, Esko I Kauppinen, Janne Raula
PURPOSE: The purpose of this study was to assess the feasibility of hydroxypropyl-β-cyclodextrin as a solubilizer for the corticosteroids prednisolone and fludrocortisone acetate in dry powder inhalation formulations. METHODS: The dry particles were simultaneously produced and coated with nanosized L-leucine crystals using an aerosol flow reactor method. The aerosolization performances of carrier-free powders were studied using Easyhaler® and Twister™ at 2 and 4 kPa pressure drops over the inhalers...
September 7, 2016: Pharmaceutical Research
https://www.readbyqxmd.com/read/27587390/amino-acids-regulate-mtorc1-by-an-obligate-two-step-mechanism
#17
Julia Dyachok, Svetlana Earnest, Erica N Iturraran, Melanie H Cobb, Elliott M Ross
The mechanistic target of rapamycin complex 1 (mTORC1) coordinates cell growth with its nutritional, hormonal, energy, and stress status. Amino acids are critical regulators of mTORC1 that permit other inputs to mTORC1 activity. However, the roles of individual amino acids and their interactions in mTORC1 activation are not well understood. Here we demonstrate that activation of mTORC1 by amino acids includes two discrete and separable steps: priming and activation. Sensitizing mTORC1 activation by priming amino acids is a prerequisite for subsequent stimulation of mTORC1 by activating amino acids...
October 21, 2016: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/27576495/acetohydroxyacid-synthases-evolution-structure-and-function
#18
REVIEW
Yadi Liu, Yanyan Li, Xiaoyuan Wang
Acetohydroxyacid synthase, a thiamine diphosphate-dependent enzyme, can condense either two pyruvate molecules to form acetolactate for synthesizing L-valine and L-leucine or pyruvate with 2-ketobutyrate to form acetohydroxybutyrate for synthesizing L-isoleucine. Because the key reaction catalyzed by acetohydroxyacid synthase in the biosynthetic pathways of branched-chain amino acids exists in plants, fungi, archaea, and bacteria, but not in animals, acetohydroxyacid synthase becomes a potential target for developing novel herbicides and antimicrobial compounds...
October 2016: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/27558952/influence-of-amino-acids-on-gastric-adaptive-relaxation-accommodation-in-rats-as-evaluated-with-a-barostat
#19
Masayuki Uchida, Chizuru Iwamoto
AIM: The present study aimed to evaluate the effects of selected straight alkyl chain, hydroxylated chain and branched chain amino acids on gastric adaptive relaxation, as these have previously been shown to have differing effects on gastric emptying. MATERIALS AND METHODS: Gastric adaptive relaxation was evaluated using a barostat in rats under urethane anesthesia. The pressure within the balloon, introduced from the mouth to the stomach, was changed stepwise from 1 to 8 mmHg...
2016: Journal of Smooth Muscle Research, Nihon Heikatsukin Gakkai Kikanshi
https://www.readbyqxmd.com/read/27551284/striga-biocontrol-on-a-toothpick-a-readily-deployable-and-inexpensive-method-for-smallholder-farmers
#20
Henry S Nzioki, Florence Oyosi, Cindy E Morris, Eylul Kaya, Alice L Pilgeram, Claire S Baker, David C Sands
Striga hermonthica (witchweed) is a parasitic weed that attacks and significantly reduces the yields of maize, sorghum, millet, and sugarcane throughout sub-Saharan Africa. Low cost management methods such as hand weeding, short crop rotations, trap cropping, or conventional biocontrol have not been effective. Likewise, Striga-tolerant or herbicide-resistant maize cultivars are higher yielding, but are often beyond the economic means of sustenance farmers. The fungal pathogen, Fusarium oxysporum f.sp. strigae, has been the object of numerous studies to develop Striga biocontrol...
2016: Frontiers in Plant Science
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