DETECTION OF CRYSTALLINE CHOLESTEROL MONOHYDRATE IN MODEL BIOMEMBRANES

模型生物膜中结晶一水胆固醇的检测

• 批准号: 6281263
• 负责人: GERALD W FEIGENSON
• 金额: $ 1.25万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-15 至 1999-08-14
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6281263
• 关键词: biological products; biomedical resource; proteins; radiography; structural biology

The mole fraction of cholesterol in biomembranes varies from nearly zero to about 0.5. The principles that determine how much cholesterol can be accomodated in a biomembrane are not yet understood. A phenomenon with a relatively simple thermodynamic description is the maximum solubility of cholesterol in a bilayer, beyond which cholesterol precipitates as crystals. We were able to detect trace amounts of cholesterol monohydrate crystals coexisting with phospholipid-cholesterol lamellae. This sensitive detection enabled us to establish the phase boundary for appearance of the crystalline phase. The x-ray source at CHESS provided the resolution needed to distinguish higher order lamellar repeats from the low angle cholesterol monohydrate lines. The value of cholesterol solubility in (16:0,18:19)-PC, (12:0,12:0)-PC, (22:113,22:113)-PC, and (16:0,18:19)-PS is mole fraction 0.66. In (16:0,18:19)-PE, the value is 0.50. The underlying molecular basis for this difference is not understood, but seems to involve headgroup area. However, a simple prediction is that the inner leaflet of cellular plasma membranes should contain less cholesterol than the outer leaflet, because of the nearly exclusive location of PE in the inner leaflet.

生物膜中胆固醇的摩尔分数因 几乎为零至约0.5。 决定多少原则 胆固醇可以在生物膜中载有胆固醇 理解。 具有相对简单热力学的现象 描述是胆固醇在双层中的最大溶解度， 除此之外，胆固醇作为晶体沉淀。 我们能够 检测痕量的胆固醇一水合物晶体共存 与磷脂 - 胆固醇薄片。 这种敏感的检测 使我们能够建立外观的相边界 晶相。 国际象棋的X射线源提供了分辨率 需要从低角度区分高阶层状重复 胆固醇一水合物线。 胆固醇溶解度在 （16：0,18：1 9）-pc，（12：0,12：0）-pc，（22：1 13,22：1 13）-pc和 （16：0,18：1 9）-ps是摩尔分数0.66。 在（16：0,18：1 9）-pe， 值为0.50。 这种差异的基本分子基础是 不了解，但似乎涉及头组区域。 但是， 简单的预测是细胞等离子体的内部小叶 膜的胆固醇应比外部小叶少， 由于PE在内部传单中的位置几乎是独家位置。