TY - JOUR

T1 - Effect of detergents on the H+-ATPase activity of inside-out and right-side-out plant plasma membrane vesicles

AU - Palmgren, Michael Gjedde

AU - Sommarin, Marianne

AU - Ulvskov, Peter

AU - Larsson, Christer

PY - 1990/1/29

Y1 - 1990/1/29

N2 - In search for a detergent to be used to assess the sidedness of plant plasma membrane vesicles by enzyme latency we tested the effect of 42 detergents on the ATPase activity of right-side-out and inside-out plasma membrane vesicles from sugar beet leaves. Most of the detergents seemed to inactivate the ATPase in addition to disrupting the permeability barrier to ATP. These were two main exceptions, namely long chain polyoxyethylene acyl ethers, such as detergents of the Brij series and Lubrol WX, and long chain lysophospholipids. These two types of detergents permeabilized the membranes at low concentrations and did not inhibit the ATPase at higher concentrations. Unmasking of latent active sites seemed to explain the activation of the plasma membrane H+-ATPase produced by long chain polyoxyethylene acyl ethers. These detergents should therefore be ideal for determination of vesicle orientation based on ATPase latency. By contrast, long chain lysophospholipids were found to be highly specific activators of the enzyme. In addition, long chain fatty acids were found to strongly inhibit ATP-dependent proton accumulation in the vesicles without inhibiting ATP hydrolysis. This uncoupling effect of the fatty acids could be abolished by the addition of fatty acid-free bovine serum albumin (BSA). Similarly, the proton transport capacity of ageing vesicles could be restored by addition of BSA. The latter findings may explain why isolated plasma membranes so often exhibit increased permeability to protons on ageing.

AB - In search for a detergent to be used to assess the sidedness of plant plasma membrane vesicles by enzyme latency we tested the effect of 42 detergents on the ATPase activity of right-side-out and inside-out plasma membrane vesicles from sugar beet leaves. Most of the detergents seemed to inactivate the ATPase in addition to disrupting the permeability barrier to ATP. These were two main exceptions, namely long chain polyoxyethylene acyl ethers, such as detergents of the Brij series and Lubrol WX, and long chain lysophospholipids. These two types of detergents permeabilized the membranes at low concentrations and did not inhibit the ATPase at higher concentrations. Unmasking of latent active sites seemed to explain the activation of the plasma membrane H+-ATPase produced by long chain polyoxyethylene acyl ethers. These detergents should therefore be ideal for determination of vesicle orientation based on ATPase latency. By contrast, long chain lysophospholipids were found to be highly specific activators of the enzyme. In addition, long chain fatty acids were found to strongly inhibit ATP-dependent proton accumulation in the vesicles without inhibiting ATP hydrolysis. This uncoupling effect of the fatty acids could be abolished by the addition of fatty acid-free bovine serum albumin (BSA). Similarly, the proton transport capacity of ageing vesicles could be restored by addition of BSA. The latter findings may explain why isolated plasma membranes so often exhibit increased permeability to protons on ageing.

KW - ATPase, H-

KW - Detergent

KW - Enzyme latency

KW - Fatty acid

KW - Lysophosphatidylcholine

KW - Plasma membrane

UR - http://www.scopus.com/inward/record.url?scp=0025117616&partnerID=8YFLogxK

U2 - 10.1016/0005-2736(90)90025-J

DO - 10.1016/0005-2736(90)90025-J

M3 - Journal article

C2 - 2154256

AN - SCOPUS:0025117616

VL - 1021

SP - 133

EP - 140

JO - B B A - Biomembranes

JF - B B A - Biomembranes

SN - 0005-2736

IS - 2

ER -