The synthesis of tools for the quantification by mass spectroscopy of biologically relevant Phosphatidyl Inositol Phosphates

有许多脂质（脂肪）分子统称为磷脂酰肌醇磷酸（PIPs），它们是细胞内事件通信的重要组成部分。当这些分子没有达到适当的水平时，细胞内的通讯途径就不能正常工作，这就会导致对细胞正常功能造成灾难性影响的变化，并可能导致从细胞死亡到无法控制的细胞生长的广泛影响。pip是由肌醇“头”组成的，肌醇“头”上可以添加磷酸盐、一个甘油单元和一个或两个脂肪酸链。传统上，研究磷酸基团在pip肌醇部分的位置是可能的，然而，在Babraham研究所，我们开发了质谱方法，使我们第一次能够同时观察完整pip中磷酸基团的变化和脂肪酸组成的差异。我们发现，在功能失调的细胞中，PIPs的脂肪酸组成和磷酸化水平都会发生变化。这项工作还处于早期阶段，我们还不知道为什么会发生这些变化，也不知道它们意味着什么。为了进一步发展这一重要方法，我们需要我们已经确定的生物活性pip的合成标准，这些pip不能在商业上获得。这些标准将用于校准质谱仪，以便我们能够准确测量组织样品中pip的水平。这些标准还将确认我们通过质谱数据的比较正确地分配了结构，并将使我们能够将分析扩展到进一步的生物学上重要的PIP物种。精确测量pip的新方法的发展将有助于学术界和制药行业开发旨在调节细胞中这些磷脂水平的新疗法。事实上，世界上几乎每一家大型制药公司目前都有旨在抑制至少一种PIP品种生产的方案，因此这些方法将立即适用于支持这一努力。此外，测量pip的脂肪酰基组成的可能性可能会开辟一个全新的研究领域，研究膳食脂肪酸对这些分子功能的影响。

There are a number of lipid (fat) molecules known collectively as Phosphatidyl Inositol Phosphates (PIPs) that are important components in the communication of events within cells. When these molecules are not found at appropriate levels, the communication pathways within the cells do not work properly and this leads to changes which can be catastrophic to the normal functioning of the cell, and can lead to a wide range of effects from cell death to uncontrollable cell growth. PIPs are made from an inositol 'head' which can have phosphates added to it, a glycerol unit and one or two fatty acid chains added to the glycerol unit. Traditionally it has only been possible to study the position of phosphate groups on the inositol part of PIPs, however, at the Babraham Institute we have developed mass spectroscopy methods which allow us, for the first time, to look both at changes in the phosphates and differences in the fatty acid composition in intact PIPs. What we have found is that changes in both the fatty acid composition of the PIPs and levels of phosphorylation occur in malfunctioning cells. This work is in the early stages and we do not yet understand why these changes occur or what they mean. To further the development of this important method we require synthetic standards of the biologically active PIPs that we have identified and which cannot be obtained commercially. These standards will be used to calibrate the mass spectrometer so that we can accurately measure the levels of PIPs in tissue samples. These standards will also confirm that we have assigned the structures correctly by the comparison of the mass spectroscopic data and will allow us to extend our analyses to further biologically important PIP species. The development of new methods to accurately measure PIPs will help both academics and the pharmaceutical industry develop novel therapies aimed at regulating the levels of these phospholipids in cells. Indeed, almost every large pharmaceutical company in the world currently has programmes aimed at inhibiting the production of at least one of these PIP species and hence these methods will have immediate applicability in supporting this effort. Further, the possibility of measuring the fatty acyl composition of PIPs may open up a whole new area of research examining the impact of dietary fatty acids on the function of these molecules.