Work

Solid-state NMR observation of chitin in whole cells by indirect 15N detection with NC, NCC, CNC and CNCC polarization transfers

Year: 2025

Type: article

Abstract: Chitin is the most important nitrogen-containing polysaccharide found on Earth. This polysaccharide is a polymer of an N-acetylglucosamine and it is a crucial structural component of fungal cell walls and crustaceans. Magic-angle spinning solid-state NMR is emerging as a powerful analytical approach to study polysaccharides in the context of intact cell walls and whole cells. The presence of an acetamido group in chitin is attractive for 15 N solid-state NMR. Here we investigate the use of various multi-step polarization transfer experiments incorporating indirect 15 N detection at moderate spinning frequency, adapted from pulse sequences commonly employed for residue resonance assignment in biosolid proteins. The 13 C, 15 N chitin spin topology slightly differs from amino acids, and we discussed the use of frequency-selective 15 N- 13 C cross-polarization transfers followed by broadband or frequency-selective homonuclear 13 C– 13 C transfers to detect chitin resonances. Demonstrated here for chitin found in the cell wall of the fungus Aspergillus fumigatus , the use of indirect 15 N detection through multi-step polarization transfers could be advantageous to investigate more complex nitrogen-containing polysaccharides found in whole cells and peptidoglycan samples. • Multi-step polarization transfers involving 15 N indirect detection are used to observe chitin signals in whole cells. • Spin topologies of chitin and amino acids are discussed in terms of 15 N indirect detection. • NC, NCC, CNC and CNCC polarization transfer experiments are presented to detect nitrogen-containing molecules. • Various polarization transfers are demonstrated on Aspergillus Fumigatus cells to detect chitin present in the cell wall.

Source: Solid State Nuclear Magnetic Resonance

DOI: 10.1016/j.ssnmr.2025.102002

Authors: Loic Delcourte, Mélanie Berbon, Marion Rodriguez, Laurence Delhaes, Birgit Habenstein, Antoine Loquet