CONTENT OF CARBOHYDRATE AND ACTIVITIES OF FRUCTOSYLTRANSFERASE AND INVERTASE IN ASPARAGUS ROOTS DURING THE FRUCTO-OLIGOSACCHARIDE-ACCUMULATING AND FRUCTO-POLYSACCHARIDE-ACCUMULATING SEASON

Contents of fructo-oligosaccharides and fructo-polysaccharides and activities of fructosyltransferases and invertase in asparagus roots harvested between July and November were studied by gel permeation chromatography (GPC) and high performance liquid chromatography (HPLC). Contents of total sugar and fructo-oligosaccharides and fructo-polysaccharides were very low in july, and then increased until September. During this period, sucrose accumulated first, second trisaccharides, and then tetra-, penta- and higher-saccharides increased in that order. 1-Kestose was the most predominant fructo-oligosaccharide isomer [degree of polymerization (DP) 3 - 6]. The fructo-polysaccharide of DP greater-than-or-equal-to 9 was 12.8 -21.7 % of total sugar from September to November; polysaccharides estimated to be DP 20 - 22 were just detectable. SST activities were very low in july, rose to a maximum in September and then decreased. Change in activity of SST was responsible for change in contents of sucrose and 1-kestose from July to November. 1F-fructosyltransferase (1F-FT) activities increased until September, were almost constant from October to November and then decreased slightly. 6G-fructosyltransferase (6G-FT) reached its highest activity early in October. 6F-SST (6-kestose producing enzyme) activity was very slight from July to November and was approximately 1/1000 of SST activity in September. This activity does not contribute to the enzymatic synthesis of the saccharides of asparagus roots. Invertase activity was nearly constant throughout. The change of activities of SST, 1F-FT and 6G-FT paralleled closely the accumulation of sucrose, 1-kestose, neokestose and other saccharides. In vitro synthesis of fructo-oligosaccharides from sucrose at 0.4, 0.1 and 0.05 M, or from 1-kestose was investigated in a fraction prepared from asparagus roots harvested in September. 1-Kestose (isokestose, 3a), neokestose (3b), nystose (4a), 1F (1-beta-D-fructofuranosyl)m-6G(1-beta-D-fructofuranosyl)n-sucrose (4b: m = 0, n = 2; 4c: m = 1, n = 1; 5a: m = 3, n = 0; 5b: m = 0, n = 3; 5c: m = 2, n = 1; 5d: m = 1, n = 2) and a mixture of hexasaccharide-isomers were synthesized from 0.4 M sucrose in 60 h. In 0.05 and 0.1 M sucrose unidentified heptasaccharides were also produced. Octa- and higher-saccharide, as well as the saccharides synthesized from sucrose, were formed from 0.1 M 1-kestose. All of -the saccharides synthesized from sucrose or 1-kestose by the asparagus enzyme preparation were identical to saccharides occurring naturally in the roots of asparagus.