Coupling Factor for Photophosphorylation in Bean Etioplasts and Chloroplasts

1971 ◽  
Vol 49 (2) ◽  
pp. 207-209 ◽  
Author(s):  
A. Horak ◽  
R. D. Hill
Keyword(s):  
Specific Activity ◽  
Coupling Factor ◽  
Spinach Chloroplast ◽  
Dependent Atpase

Extracts from either bean chloroplasts or etioplasts stimulate photophosphorylation in partially deficient chloroplast residues. Both extracts contain a latent Ca2+-dependent ATPase but the specific activity of the chloroplast extract is about sevenfold higher. The etioplast ATPase appears to have identical properties to a spinach chloroplast ATPase that has been shown to be a modified coupling factor for photophosphorylation.

scholarly journals Hepatic microsomal Ca2+-dependent ATPase. Calmodulin-dependence and partial purification

1983 ◽  
Vol 214 (1) ◽  
pp. 69-75 ◽  
Author(s):  
P B Moore ◽  
N Kraus-Friedmann
Keyword(s):  
Affinity Chromatography ◽  
Microsomal Fraction ◽  
Specific Activity ◽  
Fold Increase ◽  
Partial Purification ◽  
Dependent Atpase

The hepatic microsomal fraction contains tightly bound calmodulin as demonstrated by affinity chromatography. When this calmodulin was partially removed by EGTA treatment (0.5 mM-EGTA), the uptake of 45Ca2+ by the microsomal vesicles was stimulated by added calmodulin and inhibited by trifluoperazine (TFP). The Ca2+-dependent ATPase was partially purified on a calmodulin column. This partial purification resulted in a 500-fold increase in the specific activity of the enzyme when measured in the presence of added calmodulin. Antibodies prepared against calmodulin prevented this stimulatory effect. The fraction eluted from the calmodulin column contained several protein bands indicating that the specific activity of the Ca2+-dependent ATPase is probably still underestimated. There are likely to be other calmodulin-sensitive processes present in the hepatic microsomal fraction.

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