Abanoub Mikhael1, Kristina Jurcic2, Celine Schneider3, David Karr4, Gregory L Fisher4, Travis D Fridgen1, Alberto Diego-Taboada5, Paris E Georghiou1, Grahame Mackenzie5, Joseph Banoub1,6. 1. Department of Chemistry, Memorial University, 283 Prince Philip Dr., St John's, NL, A1B 3X7, Canada. 2. Department of Biochemistry, MALDI Mass Spectrometry Facility, Western University, Medical Sciences Building 392, London, ON, N6A 5C1, Canada. 3. NMR Facility, C-CART/CREAIT Network, Memorial University, St John's, 283 Prince Philip Dr., St John's, NL, A1B 3X7, Canada. 4. Physical Electronics, Inc. (PHI),, 18725 Lake Drive East, Chanhassen, MN, 55317, USA. 5. Department of Chemistry, University of Hull, Kingston upon Hull, HU6 7RX, UK. 6. Fisheries and Oceans Canada, Science Branch, Special Projects, 80 East White Hills Road, St John's, NL, A1C 5X1, Canada.
Abstract
RATIONALE: We report the unsolved molecular structure of the complex biopolymer sporopollenin exine extracted from Lycopodium clavatum pollen grains. METHODS: TOF-SIMS and CID-MS/MS, MALDI-TOF-MS and CID-TOF/TOF-MS/MS were used for the analysis of this complex biopolymer sporopollenin exine extracted from Lycopodium clavatum pollen grains. Solid-state 1 H- and 13 C-NMR, 2D 1 H-1 H NOESY, Rotor-synchronized 13 C{1 H} HSQC, and 13 C{1 H} multi CP-MAS NMR experiments were used to confirm the structural assigments revealed by MS and MS/MS studies. Finally, high-resolution XPS was used to check for the presence of aromatic components in sporopollenin. RESULTS: The combined MS and NMR analyses showed that sporopollenin contained poly(hydroxy acid) dendrimer-like networks with glycerol as a core unit, which accounted for the sporopollenin empirical formula. In addition, these analyses showed that the hydroxy acid monomers forming this network contained a β-diketone moiety. Moreover, MALDI-TOF-MS and MS/MS allowed us to identify a unique macrocyclic oligomeric unit composed of polyhydroxylated tetraketide-like monomers. Lastly, high-resolution X-ray photoelectron spectroscopy (HR-XPS) showed the absence of aromaticity in sporopollenin. CONCLUSIONS: We report for the first time the two main building units that form the Lycopodium clavatum sporopollenin exine. The first building unit is a macrocyclic oligomer and/or polymer composed of polyhydroxylated tetraketide-like monomeric units, which represents the main rigid backbone of the sporopollenin biopolymer. The second building unit is the poly(hydroxy acid) network in which the hydroxyl end groups can be covalently attached by ether links to the hydroxylated macrocyclic backbone to form the sporopollenin biopolymer, a spherical dendrimer. Such spherical dendrimers are a typical type of microcapsule that have been used for drug delivery applications. Finally, HR-XPS indicated the total absence of aromaticity in the sporopollenin exine.
RATIONALE: We report the unsolved molecular structure of the complex biopolymer sporopollenin exine extracted from Lycopodium clavatum pollen grains. METHODS: TOF-SIMS and CID-MS/MS, MALDI-TOF-MS and CID-TOF/TOF-MS/MS were used for the analysis of this complex biopolymer sporopollenin exine extracted from Lycopodium clavatum pollen grains. Solid-state 1 H- and 13 C-NMR, 2D 1 H-1 H NOESY, Rotor-synchronized 13 C{1 H} HSQC, and 13 C{1 H} multi CP-MAS NMR experiments were used to confirm the structural assigments revealed by MS and MS/MS studies. Finally, high-resolution XPS was used to check for the presence of aromatic components in sporopollenin. RESULTS: The combined MS and NMR analyses showed that sporopollenin contained poly(hydroxy acid) dendrimer-like networks with glycerol as a core unit, which accounted for the sporopollenin empirical formula. In addition, these analyses showed that the hydroxy acid monomers forming this network contained a β-diketone moiety. Moreover, MALDI-TOF-MS and MS/MS allowed us to identify a unique macrocyclic oligomeric unit composed of polyhydroxylated tetraketide-like monomers. Lastly, high-resolution X-ray photoelectron spectroscopy (HR-XPS) showed the absence of aromaticity in sporopollenin. CONCLUSIONS: We report for the first time the two main building units that form the Lycopodium clavatumsporopollenin exine. The first building unit is a macrocyclic oligomer and/or polymer composed of polyhydroxylated tetraketide-like monomeric units, which represents the main rigid backbone of the sporopollenin biopolymer. The second building unit is the poly(hydroxy acid) network in which the hydroxyl end groups can be covalently attached by ether links to the hydroxylated macrocyclic backbone to form the sporopollenin biopolymer, a spherical dendrimer. Such spherical dendrimers are a typical type of microcapsule that have been used for drug delivery applications. Finally, HR-XPS indicated the total absence of aromaticity in the sporopollenin exine.
Authors: Kristóf Hegedüs; Csaba Fehér; István Jalsovszky; Zoltán Kristóf; János Rohonczy; Elemér Vass; Attila Farkas; Tamás Csizmadia; Gernot Friedbacher; Peter Hantz Journal: Sci Rep Date: 2021-05-11 Impact factor: 4.379
Authors: Emma Chapman; Aimilia Meichanetzoglou; Andrew N Boa; Hanne Hetjens; Sonja Faetsch; Johnny Teuchies; Sebastian Höss; Dean Moore; Lieven Bervoets; Paul Kay; Susanne Heise; Paul Walker; Jeanette M Rotchell Journal: Bull Environ Contam Toxicol Date: 2021-08-30 Impact factor: 2.151