[et_pb_section fb_built=”1″ _builder_version=”4.23″ _module_preset=”default” custom_padding=”5px|||||” global_colors_info=”{}” theme_builder_area=”post_content”][et_pb_row _builder_version=”4.23″ _module_preset=”default” border_width_bottom=”1px” border_color_bottom=”#e2e2e2″ global_colors_info=”{}” theme_builder_area=”post_content”][et_pb_column type=”4_4″ _builder_version=”4.23″ _module_preset=”default” global_colors_info=”{}” theme_builder_area=”post_content”][et_pb_post_title meta=”off” featured_image=”off” _builder_version=”4.23″ _module_preset=”default” global_colors_info=”{}” theme_builder_area=”post_content”][\/et_pb_post_title][\/et_pb_column][\/et_pb_row][et_pb_row use_custom_gutter=”on” gutter_width=”2″ _builder_version=”4.23″ _module_preset=”default” global_colors_info=”{}” theme_builder_area=”post_content”][et_pb_column type=”4_4″ _builder_version=”4.23″ _module_preset=”default” global_colors_info=”{}” theme_builder_area=”post_content”][et_pb_text _builder_version=”4.23″ _module_preset=”default” custom_padding=”0px|||||” hover_enabled=”0″ global_colors_info=”{}” theme_builder_area=”post_content” sticky_enabled=”0″]<\/p>\n
The study of rigidity and plasticity of biological macromolecules is gaining importance in crystalline proteins using solid-state NMR. New motions are still being discovered in solids.\u00a0<\/span>Order-parameters are site-specific reporters of the amplitude of motion and can be directly extracted by measuring anisotropic interactions such as dipolar couplings, CSA and quadrupolar tensors (mainly deuterium).\u00a0<\/span>Rotational- Echo DOuble Resonance (REDOR) is a robust technique to measure heteronuclear\u00a0dipolar couplings between an isolated pair of spin-1\/2 nuclei in solid-state NMR.\u00a0<\/span>REDOR recoupling is typically used in a regime where heteronuclear couplings are a magnitude smaller than the MAS frequency. This regime allows the measurement of sufficient points in the dipolar-dephasing curve, given the stroboscopic nature of the recoupling sequence.<\/p>\n There are several challenges with the classical REDOR scheme; for instance, in the case of strongly coupled spin systems such as 13<\/sup>C-1<\/sup>H or 31<\/sup>P-1<\/sup>H, the dipolar dephasing curves decay rapidly, thereby making it challenging to measure strong couplings both in deuterated and fully protonated samples. Also, the RF requirement during REDOR recoupling scale linearly with MAS frequency and become increasingly demanding at higher MAS frequency. It becomes increasingly impossible to perform the routine and widely used 15<\/sup>N-13<\/sup>C REDOR experiments due to the limited rf field at the fastest MAS frequencies (100+ kHz) available today.<\/p>\n We have proposed two new variants of the REDOR sequence: a) SS-REDOR\u00a0<\/span>and b) mirror Symmetric REDOR (mR<\/span>\u03b5<\/span><\/sub>\u03b5+0.5\u00a0<\/span><\/sup><\/i>scheme). The sequence is particularly useful for measuring strong heteronuclear dipolar couplings such as 1<\/sup>H-31<\/sup>P, 1<\/sup>H-13<\/sup>C and 1<\/sup>H-15<\/sup>N at slow to medium MAS frequencies. The modification combines the robustness and rf requirements of REDOR with the scaling properties of shifted-REDOR, currently used to measure strong heteronuclear dipolar couplings. The \u00a0sequence\u2019s design allows independently measuring dipolar dephasing curves, both, as a function of recoupling time or change in the pulse position at one recoupling time. Two independent measurements at the same experimental conditions should improve the accuracy and precision of measuring heteronuclear dipolar coupling, especially in samples with poor signal-to-noise.\u00a0 Based on the sequence, a new class of REDOR experiments called the \u201cdeferred-REDOR\u201d have also been proposed. These lower the rf requirements by a factor of 2-2.5 compared to the REDOR. This experiment class is especially useful in situations where sufficient RF field is not available on a particular rf channel.<\/p>\n This project was in collaboration with Prof P.K.Madhu<\/p>\n \n \n [\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section]<\/p>\n","protected":false},"excerpt":{"rendered":" The study of rigidity and plasticity of biological macromolecules is gaining importance in crystalline proteins using solid-state NMR. New motions are still being discovered in solids.\u00a0Order-parameters are site-specific reporters of the amplitude of motion and can be directly extracted by measuring anisotropic interactions such as dipolar couplings, CSA and quadrupolar tensors (mainly deuterium).\u00a0Rotational- Echo DOuble […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_et_pb_use_builder":"on","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"class_list":["post-51","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.tifrh.res.in\/~vipin\/wp-json\/wp\/v2\/pages\/51"}],"collection":[{"href":"https:\/\/www.tifrh.res.in\/~vipin\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.tifrh.res.in\/~vipin\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.tifrh.res.in\/~vipin\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.tifrh.res.in\/~vipin\/wp-json\/wp\/v2\/comments?post=51"}],"version-history":[{"count":2,"href":"https:\/\/www.tifrh.res.in\/~vipin\/wp-json\/wp\/v2\/pages\/51\/revisions"}],"predecessor-version":[{"id":54,"href":"https:\/\/www.tifrh.res.in\/~vipin\/wp-json\/wp\/v2\/pages\/51\/revisions\/54"}],"wp:attachment":[{"href":"https:\/\/www.tifrh.res.in\/~vipin\/wp-json\/wp\/v2\/media?parent=51"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Limitations<\/h4>\n
Relevant Publications<\/h5>\n
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