共查询到20条相似文献,搜索用时 15 毫秒
1.
Anneli Kruve Kenji Caprice Roy Lavendomme Jan M. Wollschlger Stefan Schoder Hendrik V. Schrder Jonathan R. Nitschke Fabien B. L. Cougnon Christoph A. Schalley 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(33):11446-11450
A rapid screening method based on traveling‐wave ion‐mobility spectrometry (TWIMS) combined with tandem mass spectrometry provides insight into the topology of interlocked and knotted molecules, even when they exist in complex mixtures, such as interconverting dynamic combinatorial libraries. A TWIMS characterization of structure‐indicative fragments generated by collision‐induced dissociation (CID) together with a floppiness parameter defined based on parent‐ and fragment‐ion arrival times provide a straightforward topology identification. To demonstrate its broad applicability, this approach is applied here to six Hopf and two Solomon links, a trefoil knot, and a [3]catenate. 相似文献
2.
3.
4.
5.
Xin Ma Lien B. Lai Stella M. Lai Akiko Tanimoto Mark P. Foster Vicki H. Wysocki Venkat Gopalan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(43):11667-11671
We demonstrate that surface‐induced dissociation (SID) coupled with ion mobility mass spectrometry (IM‐MS) is a powerful tool for determining the stoichiometry of a multi‐subunit ribonucleoprotein (RNP) complex assembled in a solution containing Mg2+. We investigated Pyrococcus furiosus (Pfu) RNase P, an archaeal RNP that catalyzes tRNA 5′ maturation. Previous step‐wise, Mg2+‐dependent reconstitutions of Pfu RNase P with its catalytic RNA subunit and two interacting protein cofactor pairs (RPP21⋅RPP29 and POP5⋅RPP30) revealed functional RNP intermediates en route to the RNase P enzyme, but provided no information on subunit stoichiometry. Our native MS studies with the proteins showed RPP21⋅RPP29 and (POP5⋅RPP30)2 complexes, but indicated a 1:1 composition for all subunits when either one or both protein complexes bind the cognate RNA. These results highlight the utility of SID and IM‐MS in resolving conformational heterogeneity and yielding insights on RNP assembly. 相似文献
6.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(45):14195-14198
Described is a novel, laser‐initiated radical trifluoromethylation for protein footprinting and its broad residue coverage. .CF3 reacts with 18 of the 20 common amino acids, including Gly, Ala, Ser, Thr, Asp, and Glu, which are relatively silent with regard to .OH. This new approach to footprinting is a bridge between trifluoromethylation in materials and medicinal chemistry and structural biology and biotechnology. Its application to a membrane protein and to myoglobin show that the approach is sensitive to protein conformational change and solvent accessibility. 相似文献
7.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(13):3544-3549
A molecule's color is governed by the nature of its electronic transitions. Herein we show that the degree of charge transfer can be assessed by measuring the change in absorption induced by complexation with the betaine zwitterion. Our approach benefits from direct formation of complexes by electrospray of a mixture solution, followed by photodissociation action spectroscopy. We explored two ion groups: 1) No permanent dipole moment due to even charge delocalization (e.g. MnO4−) and 2) Non‐even charge distribution but where the charge according to resonance forms is either delocalized (e.g. oxyluciferin) or located at one site (e.g. m ‐nitrophenolate, m NP). The maximal shift for ions from (1) was <0.05 eV but as large as 0.3 eV and 0.2 eV for m NP and oxyluciferin. Hence our work supports the notion that oxyluciferin undergoes CT, and that the microenvironment can account for large variation in light emission from insects, ranging from green to red (shift of 0.3 eV). 相似文献
8.
Rebecca Beveridge Lukasz G. Migas Richard W. Kriwacki Perdita E. Barran 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(10):3146-3150
Intrinsically disordered proteins have been reported to undergo disorder‐to‐order transitions upon binding to their partners in the cell. The extent of the ordering upon binding and the lack of order prior to binding is difficult to visualize with classical structure determination methods. Binding of p27 to the Cdk2/cyclin A complex is accompanied by partial folding of p27 in the KID domain, with the retention of dynamic behavior for function, particularly in the C‐terminal half of the protein. Herein, native ion mobility mass spectrometry (IM‐MS) is employed to measure the intrinsic dynamic properties of p27, both in isolation and within the trimeric complex with Cdk2/cyclin A. The trimeric Cdk2/cyclin A/p27‐KID complex possesses significant structural heterogeneity compared to Cdk2/cyclin A. These findings support the formation of a fuzzy complex in which both the N‐ and C‐termini of p27 interact with Cdk2/cyclin A in multiple, closely associated states. 相似文献
9.
10.
11.
12.
13.
14.
15.
Rameshwar Prasad Pandit Seung Tae Kim Do Hyun Ryu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(38):13561-13566
A cyclopropanation/intramolecular rearrangement initiated by the Michael addition of in situ generated ortho‐quinone methides (o‐QMs) has been developed for the enantioselective synthesis of 2‐aryl‐2,3‐dihydrobenzofurans containing two consecutive stereogenic centers, including a quaternary carbon atom. In the presence of a chiral oxazaborolidinium ion catalyst, the reaction proceeded in excellent yields (up to 95 %) with excellent stereoselectivity (up to >99 ee, up to >20:1 d.r.). 相似文献
16.
Lei Zhang Jia‐Ni He Yuchen Liang Mengjie Hu Li Shang Xin Huang Lichun Kong Zhi‐Xiang Wang Bo Peng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(16):5370-5374
Aromatic [5,5]‐sigmatropic rearrangement is an appealing protocol for accessing 1,4‐substituted arenes. However, such a protocol has not been well utilized in organic synthesis because of the difficulties in the synthesis of the substrates, selectivity issues, and limited substrate scope. Described herein is a new [5,5]‐sigmatropic reaction utilizing readily available aryl sulfoxides and allyl nitriles. This reaction features mild reaction conditions, high chemo‐ and regioselectivity, excellent functional‐group compatibility, and broad substrate scope. Computational studies suggest that the success of the reaction can be attributed to the selective electrophilic assembly of the rearrangement precursors, in which a linear ‐C=C=N‐ linkage favors [5,5]‐sigmatropic rearrangement over the competitive [3,3]‐sigmatropic rearrangement. 相似文献
17.
Caroline C. Womack Kyle N. Crabtree Laura McCaslin Oscar Martinez Robert W. Field John F. Stanton Michael C. McCarthy 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(16):4173-4176
Carbenes are reactive molecules of the form R1 C̈ R2 that play a role in topics ranging from organic synthesis to gas‐phase oxidation chemistry. We report the first experimental structure determination of dihydroxycarbene (HO C̈ OH), one of the smallest stable singlet carbenes, using a combination of microwave rotational spectroscopy and high‐level coupled‐cluster calculations. The semi‐experimental equilibrium structure derived from five isotopic variants of HO C̈ OH contains two very short CO single bonds (ca. 1.32 Å). Detection of HO C̈ OH in the gas phase firmly establishes that it is stable to isomerization, yet it has been underrepresented in discussions of the CH2O2 chemical system and its atmospherically relevant isomers: formic acid and the Criegee intermediate CH2OO. 相似文献
18.
In the negative ion mode of electrospray ionization tandem mass spectrometry (ESI‐MS/MS) of four sulfonylurea herbicides, Smiles rearrangements were observed in rimsulfuron and nicosulfuron. In the case of rimsulfuron, two competitive gas‐phase Smiles rearrangements initiated by nitrogen anion and oxygen anion respectively were witnessed. The ion‐neutral complex was proposed as the reactive intermediate in the course of this unimolecular dissociation reaction of the oxygen attack Smiles rearrangement route. The density functional theory (DFT) was carried out to elucidate the mechanism as well as to show the possible transition states and the intermediates. 相似文献
19.
20.