Ultrastructure, polypeptide composition and photochemical activity of chloroplasts during foliar senescence of a non-yellowing mutant genotype of Festuca pratensis Huds.

Planta ◽  
1977 ◽  
Vol 137 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Howard Thomas
Keyword(s):  
Photochemical Activity ◽  
Festuca Pratensis ◽  
Polypeptide Composition ◽  
Mutant Genotype ◽  
Foliar Senescence ◽  
Photochemical Activity Of Chloroplasts

The structure and function of grana-free thylakoid membranes in gerontoplasts of senescent leaves of vicia faba l.

1988 ◽  
Vol 43 (1-2) ◽  
pp. 149-154 ◽  
Author(s):  
H. Oskar Schmidt
Keyword(s):  
Vicia Faba ◽  
Thylakoid Membranes ◽  
Photochemical Activity ◽  
Structure And Function ◽  
Polypeptide Composition ◽  
Light Harvesting Complex ◽  
Vicia Faba L ◽  
Light Protection ◽  
Flotation Method ◽  
And Function

In the course of yellowing (senescence) the leaves of Vicia faba L. lose 95% of their chlorophyll. Gerontoplasts develop from chloroplasts and aggregate with the pycnotic mitochondria and the cell nucleus in the senescent cells (organelle aggregation). The gerontoplasts contain only a few, unstacked thylakoid membranes but a large number of carotinoid-containing plastoglobuli, which after the degration of chlorophyll presumably assume the light protection of the cells. The thylakoid membranes of the gerontoplasts were isolated by means of a flotation method. Their polypeptide composition is characterized by a high proportion of light-harvesting complex. Evidence of relatively high photochemical activity shows that functional thylakoid membranes are present in the premortal senescence state of leaves and this suggests that there is functional compartmentation of the hydrolytic processes in this stage of the leaves’ development

The Photosynthetic Apparatus of Ectothiorhodospira halochloris 3. Effect of Proteolytic Digestion on the Photoactivity

1986 ◽  
Vol 41 (9-10) ◽  
pp. 873-880 ◽  
Author(s):  
R. Steiner ◽  
B. Kalumenos ◽  
H. Scheer
Keyword(s):  
Molecular Weight ◽  
Reaction Center ◽  
Photosynthetic Apparatus ◽  
Photochemical Activity ◽  
Proteinase K ◽  
Proteolytic Digestion ◽  
Polypeptide Composition ◽  
Difference Spectra ◽  
Ectothiorhodospira Halochloris ◽  
The One

Abstract Photsynthetic membranes of Rhodopseudomonas virids and Ectothiorhodospira halochloris were treated with proteinase K. The photochemical activity (light minus dark difference spectra) were compared to the polypeptide composition (SDS-polyacrylamide gel analysis). In E. halo­chloris, difference bands appear at 806 (+), 838 (+) and 854 nm (-) . All three decrease in intensity upon incubation with proteinase K., but this decrease is much slower than the proteolysis of both the reaction center and antenna related polypeptides. Photochemical activity remains high as long as a small part of the RC and two lower molecular weight polypeptides M* (22.0 kDa) and B* (15.3 kDa) are present. The M subunit is the most stable polypeptide in the RC of Rp. viridis too, and the photochemical activity is related to the remainder of this and to the one newly formed polypeptide (15.3 kDa), but doesn’t show the typical absorption shift of the antenna (B 800/1020 → B 800/960). The results are discussed quantitatively and compared to those obtained from Bchl α containing organisms.

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