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Dr. Hatice Mutlu Dr. Jean‐François Lutz 《Angewandte Chemie (International ed. in English)》2014,53(48):13010-13019
The sequencing of biopolymers such as proteins and DNA is among the most significant scientific achievements of the 20th century. Indeed, modern chemical methods for sequence analysis allow reading and understanding the codes of life. Thus, sequencing methods currently play a major role in applications as diverse as genomics, gene therapy, biotechnology, and data storage. However, in terms of fundamental science, sequencing is not really a question of molecular biology but rather a more general topic in macromolecular chemistry. Broadly speaking, it can be defined as the analysis of comonomer sequences in copolymers. However, relatively different approaches have been used in the past to study monomer sequences in biological and manmade polymers. Yet, these “cultural” differences are slowly fading away with the recent development of synthetic sequence‐controlled polymers. In this context, the aim of this Minireview is to present an overview of the tools that are currently available for sequence analysis in macromolecular science. 相似文献
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S. Munavalli D. K. Rohrbaugh H. D. Durst 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2989-2995
Thiocamphor has been found to furnish bornane, camphor, isoborneol, isobornylthiol, bornylthiol, tetrahydro-bis-(1,7,7-trimethylbicyclo[2.2.1]heptyl)-3,3′-disulfide, and three isomeric bis-(1,7,7-trimethylbicyclo[2.2.1]heptyl)-3,3′-dithiols when treated with NaBH4 either in dry THF or dry diethylene glycol diethyl ether. The origins of the above interesting compounds and their mass spectral characterization are presented in this article. 相似文献
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《液相色谱法及相关技术杂志》2012,35(6):733-747
A prediction model of the peptide retention time was developed on the basis of 358 non-phosphorylated peptides, which had various amino acid residues in the C-terminal from the casein pancreatic hydrolysates. This model was applied to predict the retention times (RT) of another 43 peptides on C4 reversed phase columns with trifluoroacetic acid (TFA) as the ion-pairing reagent, with a relatively high R2 value (0.969). Furthermore, the experimental RTs of 32 phosphopeptides were compared with the predictive RTs of their non-phosphorylated cognates. Mono- and poly-phosphopeptides seemed to elute after or before the non-phosphorylated predictive cognates, respectively. The positive charges of peptides were partly masked by the ion-pairing reagent TFA. Single and multiple phosphorylation might generally lead to an increase or reduction in the overall hydrophobicity of peptides, respectively. 相似文献
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Lei Tan Hanfeng Hu Prof. Joseph S. Francisco Prof. Yu Xia 《Angewandte Chemie (International ed. in English)》2014,53(7):1887-1890
Glycyl radicals are important bioorganic radical species involved in enzymatic catalysis. Herein, we demonstrate that the stability of glycyl‐type radicals (X‐.CH‐Y) can be tuned on a molecular level by varying the X and Y substituents and experimentally probed by mass spectrometry. This approach is based on the gas‐phase dissociation of cysteine sulfinyl radical (X‐Cys‐Y) ions through homolysis of a Cα? Cβ bond. This fragmentation produces a glycyl‐type radical upon losing CH2SO, and the degree of this loss is closely tied to the stability of the as‐formed radical. Theoretical calculations indicate that the energy of the Cα? Cβ bond homolysis is predominantly affected by the stability of the glycyl radical product through the captodative effect, rather than that of the parent sulfinyl radical. This finding suggests a novel experimental method to probe the stability of bioorganic radicals, which can potentially broaden our understanding of these important reactive intermediates. 相似文献
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Dr. Thomas Schlathölter Dr. Geert Reitsma Dmitrii Egorov Dr. Olmo Gonzalez‐Magaña Dr. Sadia Bari Leon Boschman Dr. Erwin Bodewits Dr. Kirsten Schnorr Georg Schmid Dr. Claus Dieter Schröter Dr. Robert Moshammer Prof. Dr. Ronnie Hoekstra 《Angewandte Chemie (International ed. in English)》2016,55(36):10741-10745
The fragmentation of free tenfold protonated ubiquitin in intense 70 femtosecond pulses of 90 eV photons from the FLASH facility was investigated. Mass spectrometric investigation of the fragment cations produced after removal of many electrons revealed fragmentation predominantly into immonium ions and related ions, with yields increasing linearly with intensity. Ionization clearly triggers a localized molecular response that occurs before the excitation energy equilibrates. Consistent with this interpretation, the effect is almost unaffected by the charge state, as fragmentation of sixfold deprotonated ubiquitin leads to a very similar fragmentation pattern. Ubiquitin responds to EUV multiphoton ionization as an ensemble of small peptides. 相似文献
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Natalie G. K. Wong Maria Sereli Cate S. Anstter Caroline E. H. Dessent 《Molecules (Basel, Switzerland)》2022,27(24)
Octyl methoxycinnamate (OMC) is a common UVA and UVB filter molecule that is widely used in commercial sunscreens. Here, we used gas-phase laser photodissociation spectroscopy to characterise the intrinsic photostability and photodegradation products of OMC by studying the system in its protonated form, i.e., [OMC·H]+. The major photofragments observed were m/z 179, 161, and 133, corresponding to fragmentation on either side of the ether oxygen of the ester group (m/z 179 and 161) or the C–C bond adjacent to the ester carbonyl group. Additional measurements were obtained using higher-energy collisional dissociation mass spectrometry (HCD-MS) to identify fragments that resulted from the breakdown of the vibrationally hot electronic ground state. We found that the m/z 179 and 161 ions were the main fragments produced by this route. Notably, the m/z 133 ion was not observed through HCD-MS, revealing that this product ion is only produced through a photochemical route. Our results demonstrate that UV photoexcitation of OMC is able to access a dissociative excited-state surface that uniquely leads to the rupture of the C–C bond adjacent to the key ester carbonyl group. 相似文献
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Yao C Cuadrado-Peinado ML Polásek M Turecek F 《Angewandte Chemie (International ed. in English)》2005,44(41):6708-6711
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含有28个氨基酸的复杂多肽的串级质谱全序列分析研究 总被引：2，自引：0，他引：2
利用MALDI-TOF/TOF MS和ESI-MS/MS对一种含有多达28个氨基酸的复杂合成多肽成功进行了全序列测定. 通过调节激光强度、碰撞诱导解离(CID)能量等质谱参数以及依据不同序列分析软件, 获得了涵盖所有b型和y型碎片离子的串级质谱图. 结果显示这种方法可以有效地解决de novo测序方法遇到的谱峰过于复杂导致运算死机等问题. 通过讨论如何对含有超过20个氨基酸片断的多肽进行合格串级质谱实验, 为蛋白质组学肽段序列测定提供了新的方法和思路. 相似文献
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ＩｎｔｒｏｄｕｃｔｉｏｎＡｍｉｎｏａｌｃｏｈｏｌｓａｒｅａｎｉｍｐｏｒｔａｎｔｃｌａｓｓｏｆｃｏｍｐｏｕｎｄｓｉｎｓｙｎｔｈｅｔｉｃｏｒｇａｎｉｃｒｅａｃｔｉｏｎｓ .Ｔｈｅｉｒｍｏｌｅｃｕｌｅｓｔｒｕｃｔｕｒｅｓｂｅｃｏｍｅｕｎｓｔｅａｄｙｗｈｅｎａｎａｌｙｚｅｄｂｙｅｌｅｃｔｒｏｎｉｍｐａｃｔ(ＥＩ) .ＴｈｅｆｒａｇｍｅｎｔｓｏｂｔａｉｎｅｄｆｒｏｍＥＩａｒｅｕｓｕａｌｌｙａｓ ｓｉｇｎｅｄｔｏｎｅｕｔｒａｌｌｏｓｓｅｓｓｕｃｈａｓＨ2 Ｏ ,ＣＨ3 ＯＨ (Ｆｉｇ .1) .ＥＩｉｓｎｏｔａｕｓｅｆｕｌｍｅ… 相似文献
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There is enormous interest in visualizing the chemical composition of organic material that comprises our world. A convenient method to obtain molecular information with high spatial resolution is imaging mass spectrometry. However, the internal energy deposited within molecules upon transfer to the gas phase from a surface can lead to increased fragmentation and to complications in analysis of mass spectra. Here it is shown that in laser desorption with postionization by tunable vacuum ultraviolet (VUV) radiation, the internal energy gained during laser desorption leads to minimal fragmentation of DNA bases. The internal temperature of laser‐desorbed triacontane molecules approaches 670 K, whereas the internal temperature of thymine is 800 K. A synchrotron‐based VUV postionization technique for determining translational temperatures reveals that biomolecules have translational temperatures in the range of 216–346 K. The observed low translational temperatures as well as their decrease with increased desorption laser power is explained by collisional cooling. An example of imaging mass spectrometry on an organic polymer by using laser‐desorption VUV postionization shows 5 μm feature details while using a 30 μm laser spot size and 7 ns pulse duration. Applications of laser‐desorption postionization to the analysis of cellulose, lignin, and humic acids are briefly discussed. 相似文献
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Dr. Cong H. Li Dr. George N. Khairallah Dr. Adrian K. Y. Lam Prof. Dr. Richard A. J. O'Hair Dr. Benjamin B. Kirk Prof. Dr. Stephen J. Blanksby Dr. Gabriel da Silva Prof. Dr. Uta Wille 《化学:亚洲杂志》2013,8(2):450-464
The reaction of the aromatic distonic peroxyl radical cations N‐methyl pyridinium‐4‐peroxyl (PyrOO.+) and 4‐(N,N,N‐trimethyl ammonium)‐phenyl peroxyl (AnOO.+), with symmetrical dialkyl alkynes 10a – c was studied in the gas phase by mass spectrometry. PyrOO.+ and AnOO.+ were produced through reaction of the respective distonic aryl radical cations Pyr.+ and An.+ with oxygen, O2. For the reaction of Pyr.+ with O2 an absolute rate coefficient of k1=7.1×10?12 cm3 molecule?1 s?1 and a collision efficiency of 1.2 % was determined at 298 K. The strongly electrophilic PyrOO.+ reacts with 3‐hexyne and 4‐octyne with absolute rate coefficients of khexyne=1.5×10?10 cm3 molecule?1 s?1 and koctyne=2.8×10?10 cm3 molecule?1 s?1, respectively, at 298 K. The reaction of both PyrOO.+ and AnOO.+ proceeds by radical addition to the alkyne, whereas propargylic hydrogen abstraction was observed as a very minor pathway only in the reactions involving PyrOO.+. A major reaction pathway of the vinyl radicals 11 formed upon PyrOO.+ addition to the alkynes involves γ‐fragmentation of the peroxy O? O bond and formation of PyrO.+. The PyrO.+ is rapidly trapped by intermolecular hydrogen abstraction, presumably from a propargylic methylene group in the alkyne. The reaction of the less electrophilic AnOO.+ with alkynes is considerably slower and resulted in formation of AnO.+ as the only charged product. These findings suggest that electrophilic aromatic peroxyl radicals act as oxygen atom donors, which can be used to generate α‐oxo carbenes 13 (or isomeric species) from alkynes in a single step. Besides γ‐fragmentation, a number of competing unimolecular dissociative reactions also occur in vinyl radicals 11 . The potential energy diagrams of these reactions were explored with density functional theory and ab initio methods, which enabled identification of the chemical structures of the most important products. 相似文献
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Yoon M Kalli A Lee HY Håkansson K Marsh EN 《Angewandte Chemie (International ed. in English)》2007,46(44):8455-8459
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《Chemphyschem》2004,5(4):503-508
The new radical HONF has been detected in the gas phase by neutralization–reionization mass spectrometry (NRMS). The radical has been identified and directly characterized as a gaseous isolated species, having a lifetime of at least 1 μs and a linear cis–trans structure of H‐O‐N‐F connectivity. Detection of this molecule, which is highly unstable towards the dissociation into HF and NO and kinetically sufficiently stable to be observed, represents an advance in the search for high‐energy species. 相似文献