Structural analyses of apricot pectin polysaccharides

Authors: MUHIDINOV, ZAYNIDDIN - Chemical Institute Of Tajikistan; NASRIDDINOV, ABUBAKR - Chemical Institute Of Tajikistan; Strahan, Gary; JONMURODOV, ABDUVALY - Chemical Institute Of Tajikistan; BOBOKALONOV, JAMSHED - Chemical Institute Of Tajikistan; ASHUROV, ASHURBOY - Chemical Institute Of Tajikistan; ZUMRATOV, AZIZ - Chemical Institute Of Tajikistan; Chau, Hoa; Hotchkiss, Arland; Liu, Lin

Submitted to: International Journal of Biological Macromolecules
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/9/2024
Publication Date: 9/13/2024
Citation: Muhidinov, Z.K., Nasriddinov, A.S., Strahan, G.D., Jonmurodov, A.S., Bobokalonov, J.T., Ashurov, A.I., Zumratov, A.H., Chau, H.K., Hotchkiss, A.T., Liu, L.S. 2024. Structural analyses of apricot pectin polysaccharides. International Journal of Biological Macromolecules. 279. https://doi.org/10.1016/j.ijbiomac.2024.135544.
DOI: https://doi.org/10.1016/j.ijbiomac.2024.135544

Interpretive Summary: Apricot is rich in pectin, a polysaccharide widely used in the food and pharmaceutical industries. There are more than 60 species of apricot trees in the world and most originated in Tajikistan. The value and applications of pectin are dependent on its structural properties, which are not fully characterized for apricot. In the present study, we used advanced technology to isolate and characterize two apricot pectin fractions from the same species differing from each other by size, conformation, content of sugars, and side-chain composition. This research benefits pectin researchers and producers in selection of apricot species for pectin production, and in designing procedures for pectin extraction and isolation.

Technical Abstract: Apricot pectin polysaccharides' fine structure was characterized using HPSEC, HPAEC-PAD, GC-MS, NMR and FTIR spectroscopies. Purified pectin fraction (F1AP) was composed of D-galacturonic acid, L-rhamnose, D-arabinose and D-galactose, Mw~1588 kDa. F1AP was eluted by water and with 0.2M NaCl from DEAE Sepharose resulting in two distinct fractions, F1AP1 and F1AP6, with different structures, molecular weights, and conformations, providing insights into their structural diversity. F1AP1 neutral properties were related to its association with protein. F1AP1 had a backbone of (1'4)-linked-D-galacturonic acid and (1'2)-linked-L-rhamnopyranosyl residues branched with arabinogalactan including multiple glycosidic linkages of T- a-Araf, 3-a-Araf, 5-a-Araf, T- a -Arap, 2- a-Arap, t-Galp, 2-Galp, 3-Galp, 4-Galp, 6-Galp, 2,4-Galp, 3,4-Galp, 3,6-Galp and 4,6-Galp, having methyl and acetylated groups, and a high molecular weight (1945 kDa). The Mark-Houwink exponent was 0.276, indicating a compact spherical conformation. While F1AP6 fraction consists predominately of less methylated homogalacturonan regions of pectin polysaccharides. The molar mass of this fraction was 117.5 kDa, which adopted a stiffer and random coil conformation. This knowledge allows us to evaluate how the balance of chemical structure and physical properties of the two pectin domains may manifest itself in the isolated structure of apricot pectin and its applications.