HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Ho, J. K. Articles by Hamilton, J. A. Search for Related Content PubMed PubMed Citation Articles by Ho, J. K. Articles by Hamilton, J. A. Social Bookmarking                      What's this?

Journal of Lipid Research, Vol. 43, 1429-1439, September 2002
Copyright © 2002 by Lipid Research, Inc.

Interactions of acyl carnitines with model membranes

Jet K. Ho, Richard I. Duclos, Jr. and James A. Hamilton¹

Department of Physiology and Biophysics, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118

¹ To whom correspondence should be addressed. e-mail: jhamilt{at}bu.edu

Esterification of fatty acids with the small polar molecule carnitine is a required step for the regulated flow of fatty acids into mitochondrial inner matrix. We have studied the interactions of acyl carnitines (ACs) with model membranes [egg yolk phosphatidylcholine (PC) vesicles] by ¹³C-nuclear magnetic resonance (NMR) spectroscopy. Using AC with ¹³C-enrichment of the carbonyl carbon of the acyl chain, we detected NMR signals from AC on the inside and outside leaflets of the bilayer of small unilamellar vesicles prepared by cosonication of PC and AC. However, when AC was added to the outside of pre-formed PC vesicles, only the signal for AC bound to the outer leaflet was observed, even after hours at equilibrium. The extremely slow transmembrane diffusion ("flip-flop") is consistent with the zwitterionic nature of the carnitine head group and the known requirement of transport proteins for movement of ACs through the mitochondrial membrane. The partitioning of ACs (8–18 carbons) between water and PC vesicles was studied by monitoring the [¹³C]carbonyl chemical shift of ACs as a function of pH and concentration of vesicles. Significant partitioning into the water phase was detected for ACs with chain lengths of 12 carbons or less. The effect of ACs on the integrity of the bilayer was examined in vesicles with up to 25 mol% myristoyl carnitine; no gross disruption of the bilayer was observed.

We hypothesize that the effects of high levels of long-chain AC (as found in ischemia or in certain diseases) on cell membranes result from molecular effects on membrane functions rather than from gross disruption of the lipid bilayer.

Abbreviations: AC, acyl carnitine; CMC, critical micelle concentration; PC, phosphatidylcholine; SUV, small unilamellar vesicles

Supplementary key words nuclear magnetic resonance • small unilamellar vesicles

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				M. P Corcoran, S. Lamon-Fava, and R. A Fielding Skeletal muscle lipid deposition and insulin resistance: effect of dietary fatty acids and exercise Am. J. Clinical Nutrition, March 1, 2007; 85(3): 662 - 677. [Abstract] [Full Text] [PDF]

				P. Schrauwen and M. K.C. Hesselink Oxidative Capacity, Lipotoxicity, and Mitochondrial Damage in Type 2 Diabetes Diabetes, June 1, 2004; 53(6): 1412 - 1417. [Abstract] [Full Text] [PDF]