Cholesterol Is Found To Reside in the Center of a Polyunsaturated Lipid Membrane

Citations Over TimeTop 10% of 2008 papers

Abstract

Previously, we reported neutron diffraction studies on the depth of cholesterol in phosphatidylcholine (PC) bilayers with varying amounts of acyl chain unsaturation [Harroun, T. A., et al. (2006) Biochemistry 45, 1227-1233]. The center of mass of the 2,2,3,4,4,6-D 6 deuterated sites on the sterol label was found to reside 16 A from the middle of the bilayer in 1-palmitoyl-2-oleoylphosphatidylcholine (16:0-18:1PC), 1,2-dioleoylphosphatidylcholine (18:1-18:1PC), and 1-stearoyl-2-arachidonylphosphatidylcholine (18:0-20:4PC). This location places cholesterol's hydroxyl group close to the membrane surface, indicative of the molecule in its commonly understood "upright" orientation. However, for dipolyunsaturated 20:4-20:4PC membranes the label, thus the hydroxyl group, was found sequestered in the center of the bilayer. We attributed the change in location to the high level of disorder of polyunsaturated fatty acids (PUFA) that is incompatible with proximity to the rigid steroid moiety in its usual upright orientation. From that study, the unresolved question was whether the molecule was inverted or lying flat with respect to the membrane plane, in the middle of the bilayer. We have followed up those results with additional neutron experiments employing [25,26,26,26,27,27-D 7]cholesterol, a deuterated analogue labeled in the tail. These diffraction measurements unequivocally show cholesterol lies flat in the middle of 20:4-20:4PC bilayers.

Related Papers

• → Studies on ion‐exchange membranes. XXXII. Heterogeneity in ion‐exchange membranes(1970)47 cited
• → Charge mosaic membranes prepared from laminated structures of PVA-based charged layers1. Preparation and transport properties of charged mosaic membranes(2007)34 cited
• → Synthetic an biological membranes(1982)6 cited
• → 516—Synthetic and biological membranes(1982)
• 나노 구조물을 이용한 농도 차 발전 시스템에 관한 연구(2012)