Reconstitution of rabbit sarcoplasmic reticulum calcium ATPase in a series of phosphatidylcholines containing a saturated and an unsaturated chain: suggestion of an optimal lipid environment

1993 ◽  
Vol 71 (7-8) ◽  
pp. 381-389 ◽  
Author(s):  
Paul L. J. Matthews ◽  
Eileen Bartlett ◽  
V. S. Ananthanarayanan ◽  
Kevin M. W. Keough
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Protein Interactions ◽  
Activation Energies ◽  
Calcium Atpase ◽  
Enzyme Function ◽  
Calcium Dependent ◽  
Mixed Acid ◽  
Lipid Environment ◽  
Lipid Protein Interactions ◽  
Sarcoplasmic Reticulum Calcium

The calcium-dependent ATPase from sarcoplasmic reticulum of rabbit has been purified and reconstituted in dispersions containing pure phosphatidylcholines. Each phosphatidylcholine (PC) had palmitate (16:0) at the sn-1 position of glycerol and stearate (18:0), oleate (18:1), linoleate (18:2), arachidonate (20:4), or docosahexaenoate (22:6) at the sn-2 position. The activities and activation energies of the enzyme indicated that the best enzyme function occurred when 16:0–18:1 PC or 16:0–18:2 PC was the lipid in which the ATPase was embedded. Circular dichroism measurements made as a function of temperature suggested that the protein in 16:0–18:0 and 16:0–18:1 PC behaved most like sarcoplasmic reticulum or purified ATPase. The results suggest that there may be an optimal lipid environment for the ATPase which is provided by 16:0–18:1 PC and 16:0–18:2 PC, the two most common lipids of the sarcoplasmic reticulum.Key words: lipid–protein interactions, adaptation, mixed acid lipids.

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.

scholarly journals Lipid-protein interactions are unique fingerprints for membrane proteins

2017 ◽  
Author(s):  
Valentina Corradi ◽  
Eduardo Mendez-Villuendas ◽  
Helgi I. Ingólfsson ◽  
Ruo-Xu Gu ◽  
Iwona Siuda ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Protein Interactions ◽  
Cell Membranes ◽  
Spatiotemporal Resolution ◽  
Lipid Dynamics ◽  
Lipid Species ◽  
Lipid Environment ◽  
Lipid Protein Interactions ◽  
Dynamics Simulations ◽  
Asymmetrically Distributed

ABSTRACTCell membranes contain hundreds of different proteins and lipids in an asymmetric arrangement. Understanding the lateral organization principles of these complex mixtures is essential for life and health. However, our current understanding of the detailed organization of cell membranes remains rather elusive, owing to the lack of experimental methods suitable for studying these fluctuating nanoscale assemblies of lipids and proteins with the required spatiotemporal resolution. Here, we use molecular dynamics simulations to characterize the lipid environment of ten membrane proteins. To provide a realistic lipid environment, the proteins are embedded in a model plasma membrane, where more than 60 lipid species are represented, asymmetrically distributed between leaflets. The simulations detail how each protein modulates its local lipid environment through local lipid composition, thickness, curvature and lipid dynamics. Our results provide a molecular glimpse of the complexity of lipid-protein interactions, with potentially far reaching implications for the overall organization of the cell membrane.

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