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Originally published as Biophys J. BioFAST on May 13, 2005.
doi:10.1529/biophysj.104.057307
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Biophysical Journal 89:885-894 (2005)
© 2005 The Biophysical Society

Changes of Enzyme Activity in Lipid Signaling Pathways Related to Substrate Reordering

Dino G. Salinas * {dagger}, Milton De La Fuente {dagger} and Juan G. Reyes {ddagger}

* Facultad de Ciencias de la Salud, Universidad Diego Portales, Santiago, Chile; {dagger} Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile; and {ddagger} Instituto de Química, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile

Correspondence: Address reprint requests to Dino G. Salinas, E-mail: dino.salinas{at}udp.cl.

The static fluid mosaic model of biological membranes has been progressively complemented by a dynamic membrane model that includes phospholipid reordering in domains that are proposed to extend from nanometers to microns. Kinetic models for lipolytic enzymes have only been developed for homogeneous lipid phases. In this work, we develop a generalization of the well-known surface dilution kinetic theory to cases where, in a same lipid phase, both domain and nondomain phases coexist. Our model also allows understanding the changes in enzymatic activity due to a decrease of free substrate concentration when domains are induced by peptides. This lipid reordering and domain dynamics can affect the activity of lipolytic enzymes, and can provide a simple explanation for how basic peptides, with a strong direct interaction with acidic phospholipids (such as ß-amyloid peptide), may cause a complex modulation of the activities of many important enzymes in lipid signaling pathways.



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  		SCHEME 1  Phospholipid binding kinetic model for a lipid phase with domain formation.

 


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  		SCHEME 2  Surface binding kinetic model for lipid phases with domain formation.

 





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Copyright © 2005 by the Biophysical Society.