Dispersing the crowd: Adopting 13 C direct detection for glycans

• Published in: Journal of magnetic resonance (1997) Vol. 318; p. 106792
• Main Authors: Battistel, Marcos D, Freedberg, Darón I
• Format: Journal Article
• Language: English
• Published: United States 01-09-2020
• Subjects: Carbohydrates; Natural abundance; Sialic acid; Oligosaccharide; Constant time; C direct detection; Sialyl Lewis X; Glycans; TOCSY; Low-gamma nuclei; Pure shift; Cellobiose; SMILE; Resolution
• ISSN: 1096-0856

As a direct consequence of technological advancements, the interest in direct detection of low-gamma/low-sensitivity heteronuclei for NMR experiments has been revived. Until recently, experimental development of
C/
N detected experiments has been focused on protein NMR. In the present report, we extend the use of
C-detected experiments to structural studies of glycans in natural abundance. The narrow
H and wider
C signal dispersion make glycans ideal candidates for heteronuclear detection. We show that
C-detected HSQC offers a ten-fold increase in
C dimension resolution compared to the analogous
H-detected HSQC, when the experiments are acquired for the same amount of time. The enhanced resolution comes at the expense of 2 to 3-fold loss in SNR; however, the observed signal loss is a fraction of the theoretical 8-fold difference expected between experiments. Further, we show that by combining a
H constant time element (CT), SMILE data reconstruction and
C-direct detection, complete resonance assignments of highly degenerate glycan signals are possible. Finally, we demonstrate the potential of our strategy to aid in the assignment of complex glycans, by using a novel
C-detected version of the CT-HSQC-TOCSY experiment performed on sialyl Lewis X pentasaccharide model system.