Food Biochemical Study on Fructans and Related Synthesis Enzymes

Abstract

). Abbreviations: 1 SST, sucrose : sucrose 1 fructosyltransferase; 1 FFT, fructan : fructan 1 fructosyltransferase; 6G FFT, fructan : fructan 6 G fructosyltransferase; 1 KHE, 1 kestose hydrolyzing enzyme.J. Appl. Glycosci., 55, 25 33 (2008 G -di-β-D-fructofuranosylsucrose, neokestose and sucrose from 1-kestose, while the transformant with an empty vector produced no saccharides. These results confirmed that 6G-FFT was expressed in P. pastoris. Similarly, the recombinant protein from Pichia transformed with aoft2 produced nystose from 1-kestose and the recombinant protein with aoft3 produced 1-kestose from sucrose. These results confirmed that 1-FFT and 1-SST were expressed in P. pastoris, and that the recombinant proteins had enzymatic properties similar to those of 6G-FFT, 1-FFT and 1-SST from asparagus roots. We then examined the conversion of substrate specificity from 6G-FFT to 1-FFT by point mutations in the β-fructosidase motif. The asparagine in this motif in aoft1 was changed to serine, and the mutant recombinant protein was characterized. We found that this amino acid substitution in wild-type aoft1 changed the substrate specificity from 6G-FFT to 1-FFT. Finally, we studied the activities of the main enzymes involved in the synthesis and hydrolysis of fructo-oligosaccharides during the post-harvest life of onion bulbs and asparagus spears, and discuss the mechanisms triggering these enzyme activities, as well as the mechanisms by which fructo-oligosaccharides contribute to the quality and perishability of the vegetables.

Fructan Metabolism in A. tequilana Weber Blue Variety along Its Developmental Cycle in the Field

“…The HPAEC–PAD of agave fructans, found between 14.5 and 25.5 min, showed the presence and molecular structures of DP3, DP4, and DP5 isomers (Figure ), which is supported by assignments to pure standards. We identified the following isomers (and their retention times) (Table ): 1-kestose (16.05 min), inulotriose (16.73 min), 6-kestose (17.70 min), and neokestose (18.53 min), all from the eight DP3 isomers found with DP3 (four more need to be identified); 1-nystose (19.07 min), neonystose 4c (19.92 min), inulotetraose (20.23 min), neonystose 4b (21.87 min), bifurcose (19.68 min), and 6-nystose (21.03 min), all from the seven DP4 isomers (the last two forms were identified only by comparison to published data, − leaving only one form to be established); and only 1- F fructofuranosylnystose (22.20 min), neopentaose 5c (23.02 min), and inulopentaose (23.97 min) were identified from the six DP5 isomers. Some isomers remain unidentified, but the identification of isomers with a longer DP is very complex, hence no attempt was performed in this study.…”

Molecular and Functional Characterization of Novel Fructosyltransferases and Invertases from Agave tequilana

“…When both 100 mM of sucrose and 50 mM of 1-kestose were included in the reaction both neokestose and the 4c tetrasaccharide moiety were observed ( Figure 4C and D ). Comparison with standards determined the 4c molecule to be a tetrasaccharide with an FGFF type structure (1 F ,6 G -Di-β-D-Fructofuranosylsucrose) [30] . Trace amounts of nystose were found as an impurity in the 1-kestose stock, however the nystose peak does not change in size indicating that it is not used either as an acceptor or donor for fructan polymerization.…”

Agave Fructans in Oaxaca’s Emblematic Specimens: Agave angustifolia Haw. and Agave potatorum Zucc.

“…In the case of DP5, A. angustifolia and A. potatorum accumulated almost identical amounts. FOS biosynthesis has been widely documented in the literature by [ 37 , 38 , 39 ]. Finally, we believe that the age-based decrease in simple carbohydrates and FOS is closely related to an accumulation of fructans of a HDP.…”