An f-type thioredoxin fromArabidopsis thaliana Leaves |
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Authors: | Kim Tae-Soo Joon Chul Kim Chang Duck Jin Tae Jin Han Chang -Jin Lim |
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Institution: | (1) Division of Life Sciences, Kangwon National University, 200-701 Chuncheon, Korea;(2) Department of Biology, Hallym University, 200-702 Chuncheon, Korea |
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Abstract: | Thioredoxin, a small redox protein with an active site disulfide/dithiol, is ubiquitous in bacteria, plants, and animals and
functions as a reducing agent and modulator of enzyme activity. A thioredoxin has been purified to electrophoretic homogeneity
from the leaves ofArabidopsis thaliana using procedures such as DE-52 ion exchange chromatography, Sephadex G-50 gel filtration, Q-Sepharose ion exchange chromatography,
and DEAE-Sephadex A-25 chromatography. The purified thioredoxin was determined to be a single band on SDS-PAGE, and its molecular
weight was estimated to be 21 KDa, which was much larger than those of most other known thioredoxins. It was proved to be
an f-type thioredoxin, since it could activate fructose-l,6-bisphosphatase, but it could not activate NADP+-malate dehydrogenase. As a protein disulfide reductase, it could reduce the disulfide bonds contained in insulin. As a substrate,
it showed a Km value of 20.2 μM onEscherichia coli thioredoxin reductase, and it had an optimal pH of 8.0. The molecular weight of the purified f-type thioredoxin is not consistent
with those of the five divergent h-type thioredoxins already identified by cDNA cloning. The purified f-type thioredoxin is
the first example isolated fromA. thaliana. |
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Keywords: | Arabidopsis thaliana purification thioredoxin |
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