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Fructosyltransferase activities from <em>Lolium rigidum Gaudin</em>.
- Source :
-
New Phytologist . Apr93, Vol. 123 Issue 4, p705-715. 11p. - Publication Year :
- 1993
-
Abstract
- A partial separation of sucrose: sucrose fructosyltranferase (SST) activity from invertase activity extracted from leaves of <em>Lolium rigidum</em> Gaudin was achieved by gel filtration. The SST activity was purified 54-fold with a ratio of SST activity to invertase activity of 1:1:1. the partially purified SST activity eluted with an apparent molecular mass of about 68000, had an optimum pH of 5.5 and a <em>K</em>m of 0.12 M. When incubated with sucrose concentrations ranging from 10 to 600 mM the partially purified SST activity produced mainly 1-kestose and some 6-kestose (10-15% of trisaccharide produced). SST and invertase activities declined during storage at -25°C with invertase activity declining at a faster rate. After the loss of invertase activity in storage, the partially purified SST activity synthesized only 1-ketose. When incubated with 1-ketose the partially purified SST activity synthesized neokestose (1.9 nkat ml-1), nystose (2.2 nkat ml-1) and an unidentified tetrasaccharide (1.4 nkat ml-1) indicating that the fructosyltranferase preparation also had FFT-like activity. The partially purified invertase had significant sucrose-hydrolyzing activity (25 nkat ml-1) and contained no measurable SST activity when incubated with 10-400 mM sucrose, but produced trisaccharide (1-kestose and 6-kestose, ratio 1.5:1) when incubated with 600 mM sucrose. <em>L. rigidum</em> does not normally accumulate 6-ketose. The optimum pH of the sucrose-hydrolyzing activity was 4.5 and the optimum pH of the fructosyltranferase activity of the invertase preparation was 5.5. The partially purified invertase did not have significant FFT-like activity. The results support the hypothesis that SST activity synthesizes only 1-kestose, which is a key intermediate in the synthesis of fructan in <em>L. rigidum</em>. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 0028646X
- Volume :
- 123
- Issue :
- 4
- Database :
- Academic Search Index
- Journal :
- New Phytologist
- Publication Type :
- Academic Journal
- Accession number :
- 12499861
- Full Text :
- https://doi.org/10.1111/j.1469-8137.1993.tb03781.x