Activity of Sulfate-assimilating Enzymes in Primary Leaves of Phaseolus vulgaris L. During Dark-induced Senescence
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The activity of three enzymes of assimilatory sulfate reduction, ATP sulfurylase, adenosine 5′-phosphosulfat sulfotransferase, and O-acetyl-L-serine sulfhydrylase, was measured in extracts from primary leaves of Phaseolus vulgaris L. seedlings during dark-induced senescence.
When 7-day-old seedlings were transferred from continuous light to darkness there was an increase in total activity of ATP sulfurylase (E.C. 2.7.7.4) and adenosine 5′-phosphosulfate sulfotransferase during the first 24 h. This was followed by a rapid decrease. After 6 days in the dark both enzyme activities were no longer detectable. Ribulosebisphosphate carboxylase activity, measured for comparison, increased during the first 3 days in the dark and remained constant during the following 3 days.
When the identical experiment was performed with 10-day-old seedlings, ATP sulfurylase and adenosine 5′-phosphosulfate sulfotransferase activity started decreasing already during the first 24 h in the dark with a halflife of 40 and 20 h, respectively. The half-life of ATP sulfurylase and adenosine 5′-phosphosulfate sulfotransferase activity in control seedlings kept in continuous light was 52 and 50 h, respectively. Ribulosebisphosphate carboxylase activity and chlorophyll content decreased at about the same rate in seedlings kept in the light or in the dark with half-lives of more than 100 h.
In excised primary leaves from 10-day-old seedlings, the dark-induced decrease in activity of ATP sulfurylase, adenosine 5'-phosphosulfate sulfotransferase, and ribulosebisphosphate carboxylase and the content of chlorophyll was similar to that in leaves of intact plants. Total O-acetyl-L-serine sulfhydrylase activity only decreased by about 30% in leaves of 10-day-old seedlings transferred to the dark for 7 days. The O-acetyl-L-serine sulfhydrylase activity associated with the chloroplasts decreased more rapidly than the extrachloroplastic activity.
When 7-day-old seedlings were transferred from continuous light to darkness there was an increase in total activity of ATP sulfurylase (E.C. 2.7.7.4) and adenosine 5′-phosphosulfate sulfotransferase during the first 24 h. This was followed by a rapid decrease. After 6 days in the dark both enzyme activities were no longer detectable. Ribulosebisphosphate carboxylase activity, measured for comparison, increased during the first 3 days in the dark and remained constant during the following 3 days.
When the identical experiment was performed with 10-day-old seedlings, ATP sulfurylase and adenosine 5′-phosphosulfate sulfotransferase activity started decreasing already during the first 24 h in the dark with a halflife of 40 and 20 h, respectively. The half-life of ATP sulfurylase and adenosine 5′-phosphosulfate sulfotransferase activity in control seedlings kept in continuous light was 52 and 50 h, respectively. Ribulosebisphosphate carboxylase activity and chlorophyll content decreased at about the same rate in seedlings kept in the light or in the dark with half-lives of more than 100 h.
In excised primary leaves from 10-day-old seedlings, the dark-induced decrease in activity of ATP sulfurylase, adenosine 5'-phosphosulfate sulfotransferase, and ribulosebisphosphate carboxylase and the content of chlorophyll was similar to that in leaves of intact plants. Total O-acetyl-L-serine sulfhydrylase activity only decreased by about 30% in leaves of 10-day-old seedlings transferred to the dark for 7 days. The O-acetyl-L-serine sulfhydrylase activity associated with the chloroplasts decreased more rapidly than the extrachloroplastic activity.
Date of Publication
1983-05
Publication Type
Article
Subject(s)
Language(s)
en
Contributor(s)
Schmutz, Daniel | |
Wyss, Hans-Rudolf |
Additional Credits
Series
Zeitschrift für Pflanzenphysiologie
Publisher
Gustav Fischer Verlag
ISSN
0044-328X
Access(Rights)
restricted