|
type |
Journal Article |
authors |
Lancaster, J. E.; Shaw, M. L.; Joyce, M. D.; McCallum, J. A.; McManus, M. T. |
title |
A novel alliinase from onion roots. Biochemical characterization and cDNA cloning |
journal |
Plant Physiol |
Activity |
4.4.1.4 |
Family |
4.4.1.4 |
sel |
selected |
ui |
10759524 |
year |
(2000) |
volume |
122 |
number |
4 |
pages |
1269-79 |
| |
keywords |
Amino Acid Sequence |
abstract |
We have purified a novel alliinase (EC 4.4.1.4) from roots of onion (Allium cepa L.). Two isoforms with alliinase activity (I and II) were separated by concanavalin A-Sepharose and had molecular masses of 52.7 (I) and 50.5 (II) kD on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and 51 (I) and 57.5 (II) kD by gel filtration fast-protein liquid chromatography. Isoform I had an isoelectric point of 9.3, while isoform II had isoelectric points of 7.6, 7.9, 8.1, and 8.3. The isoforms differed in their glycosylation. Both contained xylose/fucose containing complex-type N-linked glycans, and isoform II also contained terminal mannose structures. Both isoforms had activity with S-alk(en)yl-L-cysteine sulfoxides. Unlike other allium alliinases, A. cepa root isoforms had cystine lyase activity. We cloned a gene from A. cepa root cDNA and show that it codes for A. cepa root alliinase protein. Homology to other reported allium alliinase genes is 50%. The gene coded for a protein of mass 51.2 kD, with two regions of deduced amino acid sequence identical to a 25- and a 40-amino acid region, as determined experimentally. The A. cepa root alliinase cDNA was expressed mainly in A. cepa roots. The structure and function of the alliinase gene family is discussed. |
last changed |
2009/01/08 14:12 |
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