keyword
MENU ▼
Read by QxMD icon Read
search

radical sam

keyword
https://www.readbyqxmd.com/read/28067841/lectin-digestibility-and-stability-of-elderberry-antioxidants-to-heat-treatment-in-vitro
#1
Pilar Jiménez, Patricia Cabrero, Damian Cordoba-Diaz, Manuel Cordoba-Diaz, Manuel Garrosa, Tomás Girbés
Elderberry contains healthy low molecular weight nutraceuticals and lectins which are sequence-related to the elderberry allergen Sam n1. Some of these lectins are type II ribosome-inactivating proteins. The sensitivity of native lectins present in elderberry fruits and bark to the proteolysis triggered by in vitro simulated gastric and duodenal fluids has been investigated. It was found that these lectins are refractory to proteolysis. Nonetheless, incubation for 5-10 min in a boiling water bath completely sensitized them to the hydrolytic enzymes in vitro...
January 6, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28047832/su-d-bra-06-duodenal-interfraction-motion-with-abdominal-compression
#2
A Witztum, D Holyoake, S Warren, M Partridge, M Hawkins
PURPOSE: To quantify the effect of abdominal compression on duodenal motion during pancreatic radiotherapy. METHODS: Seven patients treated for pancreatic cancer were selected for analysis. Four patients were treated with abdominal compression and three without. The duodenum was contoured by the same physician on each CBCT (five CBCTs for patients with compression, four for non-compression patients). CBCTs were rigidly registered using a soft tissue match and contours were copied to the delivered plans which were all radical (BED > 50 Gy)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28045519/7-carboxy-7-deazaguanine-synthase-a-radical-s-adenosyl-l-methionine-enzyme-with-polar-tendencies
#3
Nathan A Bruender, Tsehai Aj Grell, Daniel P Dowling, Reid M McCarty, Catherine L Drennan, Vahe Bandarian
Radical S-adenosyl-L-methionine (SAM) enzymes are widely distributed and catalyze diverse reactions.  SAM binds to the unique iron atom of a site-differentiated [4Fe-4S] cluster and is reductively cleaved to generate a 5-deoxyadenosyl radical, which initiates turnover.  7-Carboxy-7-deazaguanine (CDG) synthase catalyzes a key step in the biosynthesis of 7-deazapurine containing natural products.  6-Carboxypterin (6-CP), an oxidized analog of the natural substrate 6-carboxy-5,6,7,8-tetrahydropterin (CPH4), is shown to be an alternate substrate for CDG synthase...
January 3, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28045510/anaerobic-heme-degradation-chuy-is-an-anaerobilin-reductase-that-exhibits-kinetic-cooperativity
#4
Joseph W LaMattina, Michael Anthony Delrossi, Katherine Grace Uy, Nicholas D Keul, David B Nix, William Nicholas Lanzilotta
Heme catabolism is an important biochemical process that many bacterial pathogens utilize to acquire iron. However, tetrapyrrole catabolites can be reactive and often require further processing in order for safe transport out of the cell or conversion to another useful cofactor. In previous work, we presented in vitro evidence for an anaerobic heme degradation pathway in Escherichia coli O157:H7. Consistent with reactions that have been reported for other radical SAM methyltransferases, ChuW transfers a methyl group to heme by a radical mediated mechanism and catalyzes the -scission of porphyrin macrocycle...
January 3, 2017: Biochemistry
https://www.readbyqxmd.com/read/28040895/biosynthesis-of-branched-alkoxy-groups-iterative-methyl-group-alkylation-by-a-cobalamin-dependent-radical-sam-enzyme
#5
Yuanyou Wang, Bastien Schnell, Sascha Baumann, Rolf Müller, Tadhg P Begley
The biosynthesis of branched alkoxy groups like the unique t-butyl group found in a variety of natural products, is still poorly understood. Recently, cystobactamids were isolated and identified from Cystobacter sp as novel antibacterials. These metabolites contain an isopropyl group proposed to be formed using CysS, a cobalamin-dependent radical S-adenosylmethionine (SAM) methyltransferase. Here, we reconstitute the CysS-catalyzed reaction and demonstrate that it not only performs sequential methylations of a methyl group to form isopropyl groups but remarkably also t-butyl groups on p-aminobenzoate thioester substrates...
December 31, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28027411/dna-repair-by-the-radical-sam-enzyme-spore-photoproduct-lyase-from-biochemistry-to-structural-investigations
#6
Olivier Berteau, Alhosna Benjdia
Radical S-adenosyl-L-methionine (SAM) enzymes have emerged as one of the last superfamilies of enzymes discovered to date. Arguably, it is the most versatile group of enzymes involved in at least 85 biochemical transformations. One of the founding members of this enzyme superfamily is the Spore Photoproduct (SP) lyase, a DNA repair enzyme catalyzing the direct reversal repair of a unique DNA lesion, the so-called spore photoproduct, back into two thymidine residues. Discovered more than 20 years ago in the bacterium Bacillus subtilis, SP lyase has been shown to be widespread in the endospore-forming Firmicutes from the Bacilli and Clostridia classes and to use radical-based chemistry to perform C-C bond breakage, a chemically challenging reaction...
December 27, 2016: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/27998091/tryptophan-lyase-nosl-a-cornucopia-of-5-deoxyadenosyl-radical-mediated-transformations
#7
Dhananjay M Bhandari, Dmytro Fedoseyenko, Tadhg P Begley
Tryptophan lyase (NosL) is a radical S-adenosyl-l-methionine (SAM) enzyme that catalyzes the formation of 3-methyl-2-indolic acid from l-tryptophan. In this paper, we demonstrate that the 5'-deoxyadenosyl radical is considerably more versatile in its chemistry than previously anticipated: hydrogen atom abstraction from Nα-cyclopropyltryptophan occurs at Cα rather than the amino group with NosL Y90A and replacing the substrate amine with a ketone or an alkene changes the chemistry from hydrogen atom abstraction to double bond addition...
December 21, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/27994052/bcid-is-a-radical-sam-enzyme-that-completes-bacteriochlorophyllide-e-biosynthesis-by-oxidizing-a-methyl-group-into-a-formyl-group-at-c-7
#8
Jennifer L Thweatt, Bryan H Ferlez, John H Golbeck, Donald A Bryant
Green bacteria are chlorophotorophs that synthesize bacteriochlorophyll (BChl) c, d, or e, which assemble into supramolecular, nanotubular structures in large light-harvesting structures called chlorosomes. The biosynthetic pathways of these chlorophylls are known except for one reaction. Null mutants of bciD, which encodes a putative radical-SAM protein, are unable to synthesize BChl e but accumulate BChl c; however, it is unknown whether BciD is sufficient to convert BChl c (or its precursor, bacteriochlorophyllide (BChlide) c into BChl e (or BChlide e)...
December 19, 2016: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/27979570/re-the-effect-of-broader-directed-antimicrobial-prophylaxis-including-fungal-coverage-on-perioperative-infectious-complications-after-radical-cystectomy
#9
https://www.readbyqxmd.com/read/27936626/oxidative-cyclization-in-natural-product-biosynthesis
#10
Man-Cheng Tang, Yi Zou, Kenji Watanabe, Christopher T Walsh, Yi Tang
Oxidative cyclizations are important transformations that occur widely during natural product biosynthesis. The transformations from acyclic precursors to cyclized products can afford morphed scaffolds, structural rigidity, and biological activities. Some of the most dramatic structural alterations in natural product biosynthesis occur through oxidative cyclization. In this Review, we examine the different strategies used by nature to create new intra(inter)molecular bonds via redox chemistry. This Review will cover both oxidation- and reduction-enabled cyclization mechanisms, with an emphasis on the former...
December 12, 2016: Chemical Reviews
https://www.readbyqxmd.com/read/27934015/the-b12-radical-sam-enzyme-poyc-catalyzes-valine-c%C3%AE-methylation-during-polytheonamide-biosynthesis
#11
Aubérie Parent, Alain Guillot, Alhosna Benjdia, Gwladys Chartier, Jérôme Leprince, Olivier Berteau
Genomic and metagenomic investigations have recently led to the delineation of a novel class of natural products called ribosomally synthesized and post-translationally modified peptides (RiPPs). RiPPs are ubiquitous among living organisms and include pharmaceutically relevant compounds such as antibiotics and toxins. A prominent example is polytheonamide A, which exhibits numerous post-translational modifications, some of which were unknown in ribosomal peptides until recently. Among these post-translational modifications, C-methylations have been proposed to be catalyzed by two putative radical S-adenosylmethionine (rSAM) enzymes, PoyB and PoyC...
December 7, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/27929146/reactivity-of-the-nitrogen-centered-tryptophanyl-radical-in-the-catalysis-by-the-radical-sam-enzyme-nosl
#12
Haocheng Qianzhu, Wenjuan Ji, Xinjian Ji, Leixia Chu, Chuchu Guo, Wei Lu, Wei Ding, Jiangtao Gao, Qi Zhang
The radical SAM tryptophan (Trp) lyase NosL involved in nosiheptide biosynthesis catalyzes two parallel reactions, converting l-Trp to 3-methyl-2-indolic acid (MIA) and to dehydroglycine and 3-methylindole, respectively. The two parallel reactions diverge from a nitrogen-centered tryptophanyl radical intermediate. Here we report an investigation on the intrinsic reactivity of the tryptophanyl radical using a chemical model study and DFT calculations. The kinetics of the formation and fragmentation of this nitrogen-centered radical in NosL catalysis were also studied in detail...
December 22, 2016: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/27902775/determinants-of-trna-recognition-by-the-radical-sam-enzyme-rlmn
#13
Christina M Fitzsimmons, Danica Galonić Fujimori
RlmN, a bacterial radical SAM methylating enzyme, has the unusual ability to modify two distinct types of RNA: 23S rRNA and tRNA. In rRNA, RlmN installs a methyl group at the C2 position of A2503 of 23S rRNA, while in tRNA the modification occurs at nucleotide A37, immediately adjacent to the anticodon triplet. Intriguingly, only a subset of tRNAs that contain an adenosine at position 37 are substrates for RlmN, suggesting that the enzyme carefully probes the highly conserved tRNA fold and sequence features to identify its targets...
2016: PloS One
https://www.readbyqxmd.com/read/27859789/radical-reaction-control-in-the-adomet-radical-enzyme-cdg-synthase-quee-consolidate-destabilize-accelerate
#14
Christof M Jäger, Anna K Croft
Controlling radical intermediates and thus catalysing and directing complex radical reactions is a central feature of S-adensosylmethionine (SAM)-dependent radical enzymes. We report ab initio and DFT calculations highlighting the specific influence of ion complexation, including Mg(2+) , identified as a key catalytic component on radical stability and reaction control in 7-carboxy-7-deazaguanine synthase (QueE). Radical stabilisation energies (RSEs) of key intermediates and radical clock-like model systems of the enzyme-catalysed rearrangement of 6-carboxytetrahydropterin (CPH4), reveals a directing role of Mg(2+) in destabilising both the substrate-derived radical and corresponding side reactions, with the effect that the experimentally-observed rearrangement becomes dominant over possible alternatives...
November 10, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27834682/does-viperin-function-as-a-radical-s-adenosyl-l-methionine-dependent-enzyme-in-regulating-farnesylpyrophosphate-synthase-expression-and-activity
#15
Caitlyn Makins, Soumi Ghosh, Gabriel D Román-Meléndez, Paige A Malec, Robert T Kennedy, E Neil G Marsh
Viperin is an endoplasmic reticulum-associated antiviral responsive protein that is highly up-regulated in eukaryotic cells upon viral infection through both interferon-dependent and independent pathways. Viperin is predicted to be a radical S-adenosyl-l-methionine (SAM) enzyme, but it is unknown whether viperin actually exploits radical SAM chemistry to exert its antiviral activity. We have investigated the interaction of viperin with its most firmly established cellular target, farnesyl pyrophosphate synthase (FPPS)...
December 23, 2016: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/27751449/re-a-systematic-review-and-meta-analysis-of-clinicopathologic-factors-linked-to-intravesical-recurrence-after-radical-nephroureterectomy-to-treat-upper-tract-urothelial-carcinoma
#16
https://www.readbyqxmd.com/read/27709789/comprehensive-study-of-the-macropore-and-mesopore-size-distributions-in-polymer-monoliths-using-complementary-physical-characterization-techniques-and-liquid-chromatography
#17
Sam Wouters, Tom Hauffman, Marjo C Mittelmeijer-Hazeleger, Gadi Rothenberg, Gert Desmet, Gino V Baron, Sebastiaan Eeltink
Poly(styrene-co-divinylbenzene) monolithic stationary phases with two different domain sizes were synthesized by a thermally initiated free-radical copolymerization in capillary columns. The morphology was investigated at the meso- and macroscopic level using complementary physical characterization techniques aiming at better understanding the effect of column structure on separation performance. Varying the porogenic solvent ratio yielded materials with a mode pore size of 200 nm and 1.5 μm, respectively...
December 2016: Journal of Separation Science
https://www.readbyqxmd.com/read/27705845/inactivation-efficiency-and-mechanism-of-uv-tio2-photocatalysis-against-murine-norovirus-using-a-solidified-agar-matrix
#18
Daseul Park, Hafiz Muhammad Shahbaz, Sun-Hyoung Kim, Mijin Lee, Wooseong Lee, Jong-Won Oh, Dong-Un Lee, Jiyong Park
Human norovirus (HuNoV) is the primary cause of viral gastroenteritis worldwide. Fresh blueberries are among high risk foods associated with norovirus related outbreaks. Therefore, it is important to assess intervention strategies to reduce the risk of foodborne illness. The disinfection efficiency of decontamination methods is difficult to evaluate for fruits and vegetables due to an inconsistent degree of contamination and irregular surface characteristics. The inactivation efficiency and mechanism of murine norovirus 1 (MNV-1, a surrogate for HuNoV) was studied on an experimentally prepared solidified agar matrix (SAM) to simulate blueberries using different wavelengths (A, B, C) of UV light both with and without TiO2 photocatalysis (TP)...
December 5, 2016: International Journal of Food Microbiology
https://www.readbyqxmd.com/read/27697869/improving-the-well-being-of-men-by-evaluating-and-addressing-the-gastrointestinal-late-effects-eagle-of-radical-treatment-for-prostate-cancer-study-protocol-for-a-mixed-method-implementation-project
#19
Sophia Taylor, Weyinmi Demeyin, Ann Muls, Catherine Ferguson, Damian J J Farnell, David Cohen, Jervoise Andreyev, John Green, Lesley Smith, Sam Ahmedzai, Sara Pickett, Annmarie Nelson, John Staffurth
INTRODUCTION: Radiotherapy treatment for prostate cancer can cause bowel problems, which may lead to severe difficulties for cancer survivors including limiting travel, work or socialising. These symptoms can appear at any time following radiotherapy. This study focuses on the early identification and protocol-based management of effects known to cause long-term, or even permanent, changes to the well-being of prostate cancer survivors. The rationale of this study is to improve the care offered to men and their families following pelvic radiotherapy for prostate cancer...
October 3, 2016: BMJ Open
https://www.readbyqxmd.com/read/27686626/plga-nanoparticle-encapsulation-reduces-toxicity-while-retaining-the-therapeutic-efficacy-of-etnbs-pdt-in-vitro
#20
Hsin-I Hung, Oliver J Klein, Sam W Peterson, Sarah R Rokosh, Sam Osseiran, Nicholas H Nowell, Conor L Evans
Photodynamic therapy regimens, which use light-activated molecules known as photosensitizers, are highly selective against many malignancies and can bypass certain challenging therapeutic resistance mechanisms. Photosensitizers such as the small cationic molecule EtNBS (5-ethylamino-9-diethyl-aminobenzo[a]phenothiazinium chloride) have proven potent against cancer cells that reside within acidic and hypoxic tumour microenvironments. At higher doses, however, these photosensitizers induce "dark toxicity" through light-independent mechanisms...
September 30, 2016: Scientific Reports
keyword
keyword
73063
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"