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Current Protocols in Nucleic Acid Chemistry

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https://www.readbyqxmd.com/read/28252184/using-morpholinos-to-control-gene-expression
#1
Jon D Moulton
Morpholino oligonucleotides are stable, uncharged, water-soluble molecules used to block complementary sequences of RNA, preventing processing, read-through, or protein binding at those sites. Morpholinos are typically used to block translation of mRNA and to block splicing of pre-mRNA, though they can block other interactions between biological macromolecules and RNA. Morpholinos are effective, specific, and lack non-antisense effects. They work in any cell that transcribes and translates RNA, but must be delivered into the nuclear/cytosolic compartment to be effective...
March 2, 2017: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/28252183/2-pyridinyl-thermolabile-groups-as-general-protectants-for-hydroxyl-phosphate-and-carboxyl-functions
#2
Jolanta Brzezinska, Agnieszka Witkowska, Tomasz P Kaczyński, Dominika Krygier, Tomasz Ratajczak, Marcin K Chmielewski
Application of 2-pyridinyl thermolabile protecting groups (2-PyTPGs) for protection of hydroxyl, phosphate, and carboxyl functions is presented in this unit. Their characteristic feature is a unique removal process following the intramolecular cyclization mechanism and induced only by temperature rise. Deprotection rate of 2-PyTPGs is dependent on certain parameters, such as solvent (aqueous or non-aqueous medium), pH values, and electron distribution in a pyridine ring. The presented approach pertains not only to protecting groups but also to an advanced system of controlling certain properties of 2-pyridinyl derivatives...
March 2, 2017: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/28252182/synthesis-of-geranyl-2-thiouridine-modified-rna
#3
Rui Wang, Phensinee Haruehanroengra, Jia Sheng
This unit describes the chemical synthesis of the S-geranyl-2-thiouridine (ges(2) U) phosphoramidite and its incorporation into RNA oligonucleotides through solid-phase synthesis. Starting from the 2-thiouracil nucleobase and the protected ribose, the 2-thiouridine is synthesized and the geranyl functionality is introduced into the 2-thio position by using geranyl bromide as the geranylating reagent before the conversion of this modified nucleoside into a phosphoramidite building block. The modified phosphoramidite is used to make the geranyl-RNA oligonucleotides with a solid-phase DNA synthesizer...
March 2, 2017: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/28252181/characterization-of-quadruplex-dna-structure-by-circular-dichroism
#4
Rafael Del Villar-Guerra, Robert D Gray, Jonathan B Chaires
Circular dichroism (CD) is a phenomenon that arises from the differential absorption of left- and right-handed circularly polarized light, and may be seen with optically active molecules. CD spectroscopy provides useful spectral signatures for biological macromolecules in solution, and provides low-resolution structural information about macromolecular conformation. CD spectroscopy is particularly useful for monitoring conformational changes in macromolecules upon environmental perturbations. G-quadruplex structures show unique CD spectral signatures, and CD is an important tool for characterizing their formation and global structure...
March 2, 2017: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/28252180/facile-access-to-bromonucleosides-using-sodium-monobromoisocyanurate-smbi
#5
Jyotirmoy Maity, Smriti Srivastava, Yogesh S Sanghvi, Ashok K Prasad, Roger Stromberg
Bromonucleosides constitute a significant class of molecules and are well known for their biological activity. 5-Bromouridine, 5-bromo-2'-deoxyuridine, 5-bromouridine-5'-triphosphate, and nucleotides containing 5-bromouridine have been tested and used for numerous biological studies. 8-Bromopurine nucleosides have been used as essential precursors for the synthesis of nucleosides with fluorescent properties. This unit describes protocols for the synthesis of bromonucleosides using sodium monobromoisocyanurate (SMBI) in a straightforward way...
March 2, 2017: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/28252179/deformability-calculation-for-estimation-of-the-relative-stability-of-chemically-modified-rna-duplexes
#6
Yoshiaki Masaki, Mitsuo Sekine, Kohji Seio
Chemical modification of RNA duplexes alters their stability. We have attempted to develop a computational approach to estimate the thermal stability of chemically modified duplexes. These studies revealed that the deformability of chemically modified RNA duplexes, calculated from molecular dynamics simulations, could be used as a good indicator for estimating the effect of chemical modification on duplex thermal stability. This unit describes how deformability calculation can be applied to estimate the relative stability of chemically modified RNA duplexes...
March 2, 2017: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/27911496/gram-scale-chemical-synthesis-of-base-modified-ribonucleoside-5-o-triphosphates
#7
Muthian Shanmugasundaram, Annamalai Senthilvelan, Anilkumar R Kore
This unit delineates a simple, reliable, straight-forward, general, and efficient chemical method for the synthesis of modified nucleoside-5'-O-triphosphates such as 5-methylcytidine-5'-O-triphosphate (5-Me-CTP), pseudouridine-5'-O-triphosphate (pseudo-UTP), and N(1) -methylpseudouridine-5'-O-triphosphate (N(1) -methylpseudo-UTP), starting from the corresponding nucleoside. The reaction utilizes an improved protection-free "one-pot, three-step" Ludwig synthetic strategy that involves the monophosphorylation of the nucleoside with phosphorous oxychloride followed by reaction with tributylammonium pyrophosphate and subsequent hydrolysis of the resulting cyclic intermediate to furnish the corresponding ribonucleoside triphosphate (NTP) in moderate yields...
December 1, 2016: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/27911495/synthesis-and-evaluation-of-caged-sirna-with-terminal-single-vitamin-e-modification
#8
Jiali Yang, Lijia Yu, Liangliang Zhang, Xingsu Long, Yuzhuo Ji, Xinjing Tang
RNA-induced gene silencing has been widely applied as a powerful research tool in drug development due to its sequence-specific degradation of target mRNA. Conditional regulation of gene functions with small interfering RNAs (siRNAs) is highly useful, especially when specific gene expression regulation with spatiotemporal resolution and amplitude is desired. Here, the synthesis of a series of new caged siRNAs with vitamin E (vitE) modification and/or a single photolabile linker at the 5' terminal is described...
December 1, 2016: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/27911494/determining-functional-aptamer-protein-interaction-by-biolayer-interferometry
#9
Xinhui Lou, Martin Egli, Xianbin Yang
Short single-stranded nucleic acids called aptamers are widely being explored as recognition molecules of high affinity and specificity for binding a wide range of target molecules, particularly protein targets. In biolayer interferometry (BLI), a simple Dip-and-Read approach in which the aptamer-coated biosensors are dipped into microplate wells is used to study the interactions between an aptamer and its target protein. Here we describe the protocol for the analysis of the interaction between a well-characterized anti-thrombin RNA aptamer with thrombin (Basic Protocol)...
December 1, 2016: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/27911493/rna-secondary-structure-prediction
#10
David H Mathews, Douglas H Turner, Richard M Watson
In this unit, protocols are provided for predicting RNA secondary structure with the user-friendly RNAstructure desktop computer program and the RNAstructure Web server. The minimum free energy structure and a set of suboptimal structures with similar free energies are predicted. Prediction of high-affinity oligonucleotide binding sites to a structured RNA target is also presented. © 2016 by John Wiley & Sons, Inc.
December 1, 2016: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/27911492/rolling-circle-amplification-with-chemically-modified-nucleoside-triphosphates
#11
Marcel Hollenstein, Masad J Damha
Modified nucleoside triphosphates (dN*TPs) represent facile and versatile precursors for the introduction of chemical diversity into nucleic acids. While dN*TPs have been utilized in a plethora of practical applications, very little attention has been devoted to the assessment of their compatibility with isothermal amplification strategies. In this context, rolling circle amplification (RCA) is a wide-spread enzymatic replication method in which small single-stranded DNA (ssDNA) circles serve as templates in primer extension reactions yielding very long, ssDNA products...
December 1, 2016: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/27584705/human-biomonitoring-of-dna-adducts-by-ion-trap-multistage-mass-spectrometry
#12
Jingshu Guo, Robert J Turesky
Humans are continuously exposed to hazardous chemicals in the environment. These chemicals or their electrophilic metabolites can form adducts with genomic DNA, which can lead to mutations and the initiation of cancer. The identification of DNA adducts is required for understanding exposure and the etiological role of a genotoxic chemical in cancer risk. The analytical chemist is confronted with a great challenge because the levels of DNA adducts generally occur at <1 adduct per 10(7) nucleotides, and the amount of tissue available for measurement is limited...
September 1, 2016: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/27584704/preparation-of-intrastrand-g-o-6-alkylene-o-6-g-cross-linked-oligonucleotides
#13
Derek K O'Flaherty, Christopher J Wilds
This unit describes the preparation O(6) -2'-deoxyguanosine-butylene-O(6) -2'-deoxyguanosine dimer phosphoramidites and precursors for incorporation of site-specific intrastrand cross-links (IaCL) into DNA oligonucleotides. Protected 2'-deoxyguanosine dimers are produced using the Mitsunobu reaction. IaCL DNA containing the intradimer phosphodiester are first chemically phosphorylated, followed by a ring-closing reaction using the condensing reagent 1-(2-mesitylenesulfonyl)-3-nitro-1H-1,2,4-triazole. Phosphoramidites are incorporated into oligonucleotides by solid-phase synthesis and standard deprotection and cleavage protocols are employed...
September 1, 2016: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/27584703/solid-phase-synthesis-of-oligodeoxynucleotide-analogs-containing-phosphorodithioate-linkages
#14
Xianbin Yang
The oligodeoxynucleotide phosphorodithioate modification (PS2-ODN) uses two sulfur atoms to replace two non-bridging oxygen atoms at an internucleotide phosphordiester backbone linkage. Like a natural phosphodiester ODN backbone linkage, a PS2-modified backbone linkage is achiral at phosphorus. PS2-ODNs are highly stable to nucleases and numerous in vitro assays have demonstrated their biological activity. For example, PS2-ODNs activated RNase H in vitro, strongly inhibited human immunodeficiency virus (HIV) reverse transcriptase, induced B-cell proliferation and differentiation, and bound to protein targets in the form of PS2-aptamers (thioaptamers)...
September 1, 2016: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/27584702/synthesis-of-poly-linear-shrna-expression-cassettes-through-branch-pcr
#15
Jianbing Liu, Zhen Xi
A facile and universal strategy to construct the poly linear small hairpin RNA (shRNA) expression cassettes with multiple shRNA transcription templates through polymerase chain reaction with flexible branched primers (branch-PCR) is described in this protocol. Double-stranded RNA (dsRNA) is not stable enough for the study of RNA interference (RNAi) delivery in mammalian cells. Therefore, the more stable shRNA transcription template is employed to produce the endogenous transcribed dsRNA. Then, the covalent crosslinked linear shRNA expression cassettes are constructed through the branch-PCR for the long-lasting RNAi effect in this protocol...
September 1, 2016: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/27584701/synthesis-of-4-methoxy-2-deoxynucleoside-phosphoramidites-for-incorporation-into-oligonucleotides
#16
Magdalena Petrová, Ivan Rosenberg
This unit contains detailed synthetic protocols for the preparation of 4'-methoxy 2'-deoxynucleoside phosphoramidite monomers for A, G, C, T, and U. First, 3'-silyl-protected 2'-deoxynucleosides (dNs) are converted in two steps to 4',5'-enol acetates as the key starting compounds. Next, 4'-methoxy dNs are prepared by a one-pot procedure comprising N-iodosuccinimide-promoted methoxylation, hydrolysis, and reduction of the formed intermediates. Finally, 3'-phosphoramidites of 4'-methoxy dNs are obtained by a routine three-step procedure...
September 1, 2016: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/27248786/selection-of-natural-and-base-modified-dna-aptamers-for-a-camptothecin-derivative
#17
Hiroto Fujita, Masayasu Kuwahara
Nucleic acid aptamers for small molecules are currently being developed and have a potential role in diverse applications including biosensing, diagnostics, and therapeutics involving low-molecular-weight biomarkers and drugs. To enhance and broaden their functions through chemical modification, systematic evolution of ligands by exponential enrichment (SELEX) selection has been attempted with modified DNA/RNA libraries. Recently, we demonstrated the superior efficacy of base modification for affinity enhancement and the usefulness of unnatural nucleic acid libraries for development of small-molecule aptamers...
June 1, 2016: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/27248785/pre-steady-state-kinetic-analysis-of-single-nucleotide-incorporation-by-dna-polymerases
#18
Yan Su, F Peter Guengerich
Pre-steady-state kinetic analysis is a powerful and widely used method to obtain multiple kinetic parameters. This protocol provides a step-by-step procedure for pre-steady-state kinetic analysis of single-nucleotide incorporation by a DNA polymerase. It describes the experimental details of DNA substrate annealing, reaction mixture preparation, handling of the RQF-3 rapid quench-flow instrument, denaturing polyacrylamide DNA gel preparation, electrophoresis, quantitation, and data analysis. The core and unique part of this protocol is the rationale for preparation of the reaction mixture (the ratio of the polymerase to the DNA substrate) and methods for conducting pre-steady-state assays on an RQF-3 rapid quench-flow instrument, as well as data interpretation after analysis...
June 1, 2016: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/27248784/diffraction-techniques-in-structural-biology
#19
REVIEW
Martin Egli
A detailed understanding of chemical and biological function and the mechanisms underlying the molecular activities ultimately requires atomic-resolution structural data. Diffraction-based techniques such as single-crystal X-ray crystallography, electron microscopy, and neutron diffraction are well established and they have paved the road to the stunning successes of modern-day structural biology. The major advances achieved in the last twenty years in all aspects of structural research, including sample preparation, crystallization, the construction of synchrotron and spallation sources, phasing approaches, and high-speed computing and visualization, now provide specialists and nonspecialists alike with a steady flow of molecular images of unprecedented detail...
June 1, 2016: Current Protocols in Nucleic Acid Chemistry
https://www.readbyqxmd.com/read/27248783/simple-high-yield-syntheses-of-dna-duplexes-containing-interstrand-dna-dna-cross-links-between-an-n-4-aminocytidine-residue-and-an-abasic-site
#20
Jacqueline Gamboa Varela, Kent S Gates
The protocol describes the preparation and purification of interstrand DNA-DNA cross-links derived from the reaction of an N(4) -aminocytidine residue with an abasic site in duplex DNA. The procedures employ inexpensive, commercially available chemicals and enzymes to carry out post-synthetic modification of commercially available oligodeoxynucleotides. The yield of cross-linked duplex is typically better than 90%. If purification is required, the cross-linked duplex can be readily separated from single-stranded DNA starting materials by denaturing gel electrophoresis...
June 1, 2016: Current Protocols in Nucleic Acid Chemistry
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