Effect of phospholipase A on the structure and functions of membrane vesicles from Mycobacterium phlei

Prasad, R. ; Kalra, V. K. ; Brodie, A. F. (1975) Effect of phospholipase A on the structure and functions of membrane vesicles from Mycobacterium phlei Journal of Biological Chemistry, 250 (10). pp. 3690-3698. ISSN 0021-9258

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Official URL: http://www.jbc.org/content/250/10/3690.short

Abstract

The phospholipid composition of the electron transport particles and coupling factor-depleted electron transport particles of Mycobacterium phlei are the same, but they differ in contents. The accessibility of partially purified phospholipase A to these membrane phospholipids was found to be different. Treatment of membranes of Mycobacterium phlei with phospholipase A impairs the rate of oxidation as well as phosphorylation. The inhibition of phosphorylation can be reversed by washing the membranes with defatted bovine serum albumin. The reconstitution of membrane-bound coupling factor-latent ATPase activity to phospholipase A-treated depleted electron transport particles and their capacity to couple phosphorylation to oxidation of substrates remained unaffected after phospholipase A treatment. However, the pH gradient as measured by bromthymol blue was not restored after reconstitution of phospholipase A-treated depleted electron transport particles with membrane-bound coupling factor-latent ATPase. These findings show that the phosphorylation coupled to the oxidation of substrates can take place without a pronounced pH gradient in these membrane vesicles. The dye 1-anilino-8-naphthalene sulfonic acid (ANS) exhibited low levels of energized and nonenergized fluorescence in phospholipase A-treated membranes. This decrease in the level of ANS fluorescence in phospholipase A-treated membranes was found to be directly related to the amount of phospholipids cleaved. The decrease in the energy-dependent ANS response in phospholipase A-treated electron transport particles, as compared with untreated electron transport particles, was shown to be a result of a change in the apparent Kd of the dye-membrane complex, and of a decrease in the number of irreversible or slowly reversible binding sites, with no change in the relative quantum efficiency of the dye. The decrease in ANS fluorescence in phospholipase A-treated particles appears to be due to a decrease in the hydrophobicity of the membranes.

Item Type:Article
Source:Copyright of this article belongs to The American Society for Biochemistry and Molecular Biology.
ID Code:39302
Deposited On:10 May 2011 09:13
Last Modified:17 May 2016 21:48

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