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Solubilization of galactosyltransferase that synthesizes 1,4-β-galactan side chains in pectic rhamnogalacturonan I.
- Source :
-
Physiologia Plantarum . Apr2002, Vol. 114 Issue 4, p540-548. 9p. - Publication Year :
- 2002
-
Abstract
- β-1,4-Galactan galactosyltransferase (GT) activity was solubilized from potato microsomal membranes in the presence of 78 mM 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulphonic acid. The solubilized GT activity transferred 14[C]galactose from UDP-14[C]galactose onto the acceptor-substrates composed of rhamnogalacturonan (RG) with short galactan chains (RG-A, approximately 1.2 MDa, mol% Gal/Rha = 0.7; RG-B, approximately 21 kDa, mol% Gal/Rha = 1.2). However, shorter RG containing short galactan chains (approximately 2 kDa and 1.2 kDa), RG oligomers without galactosyl-residues, galactan, and galactooligomers did not act as acceptor-substrates. Optimal pH for 14[C] incorporation onto RG-A and RG-B was around 5.6 and 7.5, respectively. The 14[C]-labelled products synthesized upon RG-A and RG-B could be digested with a RG specific lyase into smaller RG fragments. 1,4-β-Endog alactanase could not digest the former product, whereas the latter product was digested to 14[C]galactobiose and 14[C]galactose. This demonstrates that at least two GT activities were solubilized from potato microsomal membranes. One had optimal pH around 5.6 to transfer galactosyl residues onto RG-A, whereas the other had optimal pH around 7.5 to transfer galactosyl residues onto RG-B. Both synthesized galactan attached to the RG backbone of RG-A and RG-B, and the galactan synthesized onto the RG-B acceptor was 1,4-β-linked. [ABSTRACT FROM AUTHOR]
- Subjects :
- *GALACTOSYLTRANSFERASES
*GALACTANS
Subjects
Details
- Language :
- English
- ISSN :
- 00319317
- Volume :
- 114
- Issue :
- 4
- Database :
- Academic Search Index
- Journal :
- Physiologia Plantarum
- Publication Type :
- Academic Journal
- Accession number :
- 6571743
- Full Text :
- https://doi.org/10.1034/j.1399-3054.2002.1140406.x