13C-13C Homonuclear Recoupling in Solid-State Nuclear Magnetic Resonance at a Moderately High Magic-Angle-Spinning Frequency

Venus Singh Mithu,Subha Bakthavatsalam,Perunthiruthy K Madhu,Annalisa Pastore

doi:10.1371/journal.pone.0050504

Venus Singh Mithu, Subha Bakthavatsalam + Show 2 more

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https://doi.org/10.1371/journal.pone.0050504

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Journal: PloS one	Publication Date: Jan 10, 2013
Citations: 7	License type: CC BY 4.0

Affiliation: Tata Institute of Fundamental Research

Abstract

Two-dimensional 13C-13C correlation experiments are widely employed in structure determination of protein assemblies using solid-state nuclear magnetic resonance. Here, we investigate the process of 13C-13C magnetisation transfer at a moderate magic-angle-spinning frequency of 30 kHz using some of the prominent second-order dipolar recoupling schemes. The effect of isotropic chemical-shift difference and spatial distance between two carbons and amplitude of radio frequency on 1H channel on the magnetisation transfer efficiency of these schemes is discussed in detail.

Highlights

Technical advances in the past decade have made solid-state nuclear magnetic resonance (SSNMR) a powerful tool in the field of structural biology, especially for systems like protein assemblies and membrane proteins [1,2,3,4,5]
Proton Driven Spin Diffusion (PDSD) [23], Dipolar Assisted Rotational Resonance (DARR) [24], Rf-Assisted Diffusion (RAD) [25], Phase Alternated Recoupling Irradiation Schemes (PARIS [26,27] and PARIS-xy [28]), and the recently introduced Second-order Hamiltonian among Analogous Nuclei Generated by Heteronuclear Assistance Irradiation (SHANGHAI) [29] come under the category of second-order recoupling schemes
We found that even for broad-banded schemes like PARIS-xy (m = 1)(N = 1/2), PARIS-xy (m = 1)(N = 2), and PARIS-xy (m = 2)(N = 1/2), magnetisation transfer efficiencies can be seriously attenuated by a wrong choice of n1H

Summary

Introduction

Technical advances in the past decade have made solid-state nuclear magnetic resonance (SSNMR) a powerful tool in the field of structural biology, especially for systems like protein assemblies and membrane proteins [1,2,3,4,5]. Structure information in SSNMR is mostly derived from the less abundant spins like 13C and 15N, with through-space 2D 13C-13C correlation experiments playing a prominent role [7]. Through-space 13C-13C correlations can be obtained with firstorder homonuclear dipolar recoupling schemes [10,11,12,13,14] These schemes suffer from dipolar truncation effects where strong dipolar couplings mask the weaker ones [15]. Whilst this effect helps in the selective observation of directly bonded carbon atoms, which is very helpful in assigning the 13C resonances in a protein skeleton, the same effect makes these schemes unsuitable for observing longrange 13C-13C contacts, which are essential for determining tertiary structure of proteins.

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