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31.
We describe the design and exploration of new buried polar groups to control coiled-coil dimerization. Employing our recently described method for on-resin guanidinylation, we have prepared coiled-coil peptides with a single core guanidine, spaced from the backbone by 1-3 methylene groups. Heterodimeric mixtures of these sequences with guanidine, amide, and carboxylic acid binding partners form a large number of reasonably stable coiled coils (T(m) > or = 60 degrees C). A detailed stability trend examination reveals that asparagine/acid pairs are sharply sensitive to acid residue chain length (Asn/Asp much worse than Asn/Glu), while guanidine/acid pairs are largely insensitive. This has been exploited to create orthogonal recognition pairs which establish the capacity to form two distinct heterodimeric coiled coils by simple mixing of four different peptides. One dimer has buried core asparagines, while the other pairs aspartic acid with any of three guanidinylated side chains. Specificity of this behavior is underscored by failure of glutamic acid substituted sequences to perform accordingly. The successful alternate pairs are further characterized by various biophysical methods (circular dichroism, ultracentrifugation, thermal and chemical denaturation, affinity tags). 相似文献
32.
We describe simultaneous formation of three distinct heterodimeric coiled coils from a mixture of six different peptides. The choice among electrostatically viable complexes is governed by alignment of buried core residues, including a fundamentally new interaction that exploits urea-terminated side chains. Buried urea/urea contacts lead to extremely stable dimeric coiled coils, with T(m) values between 63 and 79 degrees C. Core ureas can also form stable complexes with a variety of other polar groups, including guanidines, acids, and amides. 相似文献
33.
L. A. Stables R. P. Kennan A. W. Anderson R. T. Constable J. C. Gore 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1999,136(2):143
The DIET (ordualintervalechotrain) sequence, a modification of thefastspinecho (FSE) sequence that selectively reduces signal from fat in MR images, has been investigated. The DIET sequence uses an initial echo spacing longer than that of a conventional FSE sequence, thus allowingJcoupling-induced dephasing to take effect. The sequence is evaluated theoretically, and its effectiveness on a hydrocarbon (1-pentene) is demonstrated numerically using density matrix calculations. The sequence is also evaluated experimentally usingin vitrosolutions andin vivoimaging. The efficacy of the sequence is compared for different lipid chemical structures, field strengths, and pulse sequence parameters. 相似文献
34.
S Chanda Sarmishtha Bhattacharyya Tumpa Bhattacharjee SS Ghugre Swapan Kumar Basu S Muralithar RP Singh B Mukherjee RK Bhowmik SN Ray 《Pramana》2001,57(1):175-179
The high spin states in N=80 139Pr have been investigated by in-beam γ-spectroscopic techniques following the reaction 130Te (14N, 5n) reaction at E=75 MeV, using a gamma detector array, consisting of seven 23% compton-suppressed high purity germanium detectors and a multiplicity
ball of fourteen bismuth germanate elements. Based on γ-γ coincidence data, the level scheme of 139Pr has been considerably extended up to 7.2 MeV excitation. Tentative spin-parity assignments are done for the newly proposed
levels on the basis of the DCO ratios corresponding to strong gates and the available information from the earlier light ion
experiments. 相似文献
35.
[structure: see text] The design of antiparallel coiled-coil heterotrimers with singly mismatched electrostatic interfaces is reported. The new complexes exhibit expected properties for well-formed coiled-coils and have stabilities comparable to those of parallel analogues. The mismatched interface facilitates switching from a parallel to antiparallel complex by pH-triggered strand exchange. 相似文献
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JM Chatterjee M Saha Sarkar S Bhattacharya P Banerjee S Sarkar RP Singh S Murulithar RK Bhowmik 《Pramana》2001,57(1):165-169
High-spin states of 95,97Mo (Z=42, N=53,55) nuclei have been investigated through 82Se(18O, xn) reaction at Eb=60 MeV. The level scheme in 95Mo has been observed upto ≏ 10 MeV in the present experiment. The level structure shows mainly single particle character.
In 97Mo, the ground state level sequence has been extended to ≏ 4.5 MeV while the previous information had been up to 2.4 MeV.
A negative parity band built on 1437 keV (11/2−) excited state has been extended to 5.5 MeV. The structure seems to show a coexistence of single particle and collective
modes of excitation. Properties of both the nuclei have been compared with shell model calculations using OXBASH. 相似文献
39.
The nucleus 30 65 Zn was studied using the 52Cr(16O, 2pn)65Zn reaction at a beam energy of 65 MeV. The level scheme is extended up to an excitation energy of 10.57 MeV for spin-parity (41/2?) with several newly observed transitions placed in it. 相似文献