Chlorophyll-protein complex composition and photochemical activity in developing chloroplasts from greening barley seedlings |
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Authors: | Kent O Burkey |
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Institution: | (1) Agricultural Research Service, United States Department of Agriculture, 27695-7631 Raleigh, NC, USA;(2) Department of Crop Science, North Carolina State University, 27695-7631 Raleigh, NC, USA;(3) Department of Botany, North Carolina State University, 27695-7631 Raleigh, NC, USA |
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Abstract: | The time course for the observation of intact chlorophyll-protein (CP) complexes during barley chloroplast development was measured by mild sodium dodecyl sulfate polyacrylamide gel electrophoresis. The procedure required extraction of thylakoid membranes with sodium bromide to remove extrinsic proteins. During the early stages of greening, the proteins extracted with sodium bromide included polypeptides from the cell nucleus that associate with developing thylakoid membranes during isolation and interfere with the separation of CP complexes by electrophoresis. Photosystem I CP complexes were observed before the photosystem II and light-harvesting CP complexes during the initial stages of barley chloroplast development. Photosystem I activity was observed before the photosystem I CP complex was detected whereas photosystem II activity coincided with the appearance of the CP complex associated with photosystem II. Throughout chloroplast development, the percentage of the total chlorophyll associated with photosystem I remained constant whereas the amount of chlorophyll associated with photosystem II and the light-harvesting complex increased. The CP composition of thylakoid membranes from the early stages of greening was difficult to quantitate because a large amount of chlorophyll was released from the CP complexes during detergent extraction. As chloroplast development proceeded, a decrease was observed in the amount of chlorophyll released from the CP complexes by detergent action. The decrease suggested that the CP complexes were stabilized during the later stages of development.Abbreviations Chl
chlorophyll
- CP
chlorophyll-protein
- CPI
P700 chlorophyll-a protein complex of photosystem I
- CPa
electrophoretic band that contains the photosystem II reaction center complexes and a variable amount of the photosystem I light-harvesting complex
- CP A/B
the major light-harvesting complex associated with photosystem II
- DCIP
2,6-dichlorophenolindophenol
- DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- DPC
diphenyl carbazide
- MV
methyl viologen
- PAR
photosynthetically active radiation
- PSI
photosystem I
- PSII
photosystem II
- SDS
sodium dodecyl sulfate
- SDS-PAGE
sodium dodecyl sulfate polyacrylamide gel electrophoresis
- TEMED
N,N,N ,N -tetramethylethylenediamine
- TMPD
N,N,N ,N -tetramethyl-p-phenylenediamine
Cooperative investigations of the United States Department of Agriculture, Agricultural Research Service, and the North Carolina Agricultural Research Service, Raleigh, NC 27695-7601. Paper No. 9949 of the Journal Series of the North Carolina Agricultural Research Service, Raleight, NC 27695-7601. |
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Keywords: | barley chlorophyll-protein complexes chloroplast development mild SDS-PAGE thylakoid membranes |
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