Functional characterization of lanthanide binding sites in the sarcoplasmic reticulum calcium-ATPase: do lanthanide ions bind to the calcium transport site?

Biochemistry ◽  
1991 ◽  
Vol 30 (41) ◽  
pp. 9966-9973 ◽  
Author(s):  
Tarou Ogurusu ◽  
Shigeo Wakabayashi ◽  
Munekazu Shigekawa
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Binding Sites ◽  
Calcium Transport ◽  
Functional Characterization ◽  
Calcium Atpase ◽  
Lanthanide Ions ◽  
Sarcoplasmic Reticulum Calcium ◽  
Transport Site

A Conformational Transition of the Sarcoplasmic Reticulum Calcium Transport ATPase Induced by Vanadate

1983 ◽  
Vol 38 (11-12) ◽  
pp. 1015-1022 ◽  
Author(s):  
Wilhelm Hasselbach ◽  
Pankaj Medda ◽  
Andrea Migala ◽  
Bruno Agostini
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Binding Sites ◽  
Calcium Binding ◽  
Calcium Transport ◽  
Conformational Transition ◽  
Transport Atpase ◽  
Calcium Binding Sites ◽  
Protein Particles ◽  
Sarcoplasmic Reticulum Calcium ◽  
Internal Calcium

Vanadate binding to sarcoplasmic reticulum vesicles results in the loss of the externally located high affinity calcium binding sites of the calcium transport ATPase. Conversely the occupation by calcium of the internally located low affinity sites in the vanadate enzyme complex leads to the release of vanadate. Since the total number of calcium binding sites is not diminished by vanadate binding but slightly increases we conclude that vanadate binding induces a transition of the enzymes external high to internal low affinity calcium binding sites. The transposition of external to internal calcium binding sites is accompanied by a definite change in the structure of the sarcoplasmic reticulum membranes. On vanadate binding the asymmetrically arranged electron dense protein particles become symmetrically distributed

Pressure Effects on the Interactions of the Sarcoplasmic Reticulum Calcium Transport Enzyme with Calcium and para-Nitrophenyl Phosphate

1987 ◽  
Vol 42 (5) ◽  
pp. 641-652 ◽  
Author(s):  
Wilhelm Hasselbach ◽  
Lore Stephan
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Transport ◽  
Activation Volume ◽  
Reaction Scheme ◽  
Pressure Effects ◽  
Calcium Dependent ◽  
Nitrophenyl Phosphate ◽  
Hydrolysis Of ◽  
Sarcoplasmic Reticulum Calcium ◽  
Effect Of Hydrostatic Pressure

The effect of hydrostatic pressure on calcium dependent p-nitrophenyl phosphate hydrolysis of the sarcoplasmic reticulum calcium transport enzyme has been investigated at different degree of enzyme saturation by calcium and Mg-p-nitrophenyl phosphate to distinguish between activation and binding volumes. The enzyme saturated by both ligands displays a significant dependence of the activation volume on pressure, rising from 20 ml/mol at atmospheric pressure (0.1 MPa) to 80 ml/mol at 100 MPa. At subsaturating concentration of Mg-p-nitrophenyl phosphate an activation volume of 35 ml/mol prevails between 0.1 and 40 MPa. At subsaturating concentration of calcium the activation volume approximates 80 ml/mol in the same pressure range. The binding volume for both substrates is likewise pressure dependent falling from 20 ml/mol to 0 ml/mol for Mg-p-nitrophenyl phosphate and rising from 67 ml/mol to 155 ml/mol for calcium. The pressure dependence of activation and binding volumes is analysed on account of a simplified reaction scheme yielding activation volumes and rate constants for individual reaction steps.

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