排序方式: 共有49条查询结果,搜索用时 31 毫秒
21.
Joshua L. Wort Katrin Ackermann Angeliki Giannoulis Alan J. Stewart David G. Norman Bela E. Bode 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(34):11807-11811
Electron paramagnetic resonance (EPR) distance measurements are making increasingly important contributions to the studies of biomolecules by providing highly accurate geometric constraints. Combining double‐histidine motifs with CuII spin labels can further increase the precision of distance measurements. It is also useful for proteins containing essential cysteines that can interfere with thiol‐specific labelling. However, the non‐covalent CuII coordination approach is vulnerable to low binding‐affinity. Herein, dissociation constants (KD) are investigated directly from the modulation depths of relaxation‐induced dipolar modulation enhancement (RIDME) EPR experiments. This reveals low‐ to sub‐μm CuII KDs under EPR distance measurement conditions at cryogenic temperatures. We show the feasibility of exploiting the double‐histidine motif for EPR applications even at sub‐μm protein concentrations in orthogonally labelled CuII–nitroxide systems using a commercial Q‐band EPR instrument. 相似文献
22.
Alice C. Harnden Elizaveta A. Suturina Andrei S. Batsanov P. Kanthi Senanayake Mark A. Fox Kevin Mason Michele Vonci Eric J. L. McInnes Nicholas F. Chilton David Parker 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(30):10396-10400
In two closely related series of eight‐coordinate lanthanide complexes, a switch in the sign of the dominant ligand field parameter and striking variations in the sign, amplitude and orientation of the main component of the magnetic susceptibility tensor as the Ln3+ ion is permuted conspire to mask modest changes in NMR paramagnetic shifts, but are evident in Yb EPR and Eu emission spectra. 相似文献
23.
24.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(11):2960-2964
The cellular environment of proteins differs considerably from in vitro conditions under which most studies of protein structures are carried out. Therefore, there is a growing interest in determining dynamics and structures of proteins in the cell. A key factor for in‐cell distance measurements by the double electron–electron resonance (DEER) method in proteins is the nature of the used spin label. Here we present a newly designed GdIII spin label, a thiol‐specific DOTA‐derivative (DO3MA‐3BrPy), which features chemical stability and kinetic inertness, high efficiency in protein labelling, a short rigid tether, as well as favorable spectroscopic properties, all are particularly suitable for in‐cell distance measurements by the DEER method carried out at W‐band frequencies. The high performance of DO3MA‐3BrPy‐GdIII is demonstrated on doubly labelled ubiquitin D39C/E64C, both in vitro and in HeLa cells. High‐quality DEER data could be obtained in HeLa cells up to 12 h after protein delivery at in‐cell protein concentrations as low as 5–10 μm . 相似文献
25.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(2):525-529
While natural photosynthesis serves as the model system for efficient charge separation and decoupling of redox reactions, bio‐inspired artificial systems typically lack applicability owing to synthetic challenges and structural complexity. We present herein a simple and inexpensive system that, under solar irradiation, forms highly reductive radicals in the presence of an electron donor, with lifetimes exceeding the diurnal cycle. This radical species is formed within a cyanamide‐functionalized polymeric network of heptazine units and can give off its trapped electrons in the dark to yield H2, triggered by a co‐catalyst, thus enabling the temporal decoupling of the light and dark reactions of photocatalytic hydrogen production through the radical′s longevity. The system introduced here thus demonstrates a new approach for storing sunlight as long‐lived radicals, and provides the structural basis for designing photocatalysts with long‐lived photo‐induced states. 相似文献
26.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(46):14694-14698
A terminal Mo phosphide was prepared through the group transfer of both P and Cl atoms from chloro‐substituted dibenzo‐7λ3‐phosphanorbornadiene. This compound represents the first structurally characterized terminal transition‐metal phosphide with valence d electrons. In the tetragonal ligand field, these electrons populate an orbital of dxy parentage, an electronic configuration that accommodates both metal d electrons and a formal M≡P triple bond. Single‐electron oxidation affords a transient open‐shell terminal phosphide cation with significant spin density on P, as corroborated by continuous wave (CW) and pulse electron paramagnetic resonance (EPR) characterization. Facile P−P bond formation occurs from this species through intermolecular phosphide coupling. 相似文献
27.
28.
29.
30.