W BAND STUDIES OF NEUROMELANIN

研究的总体目标是确定组成 (特别是主要单体单元及其衍生物)和 神经黑色素(NM)的物理化学性质及其关系 这些特性可能在病理生理学中发挥作用，包括 NM改变在衰老和退行性疾病中的作用 尤其是帕金森氏症。由于NMS起源于不同 它们的EPR谱应该显示出微妙的但 在不同的情况下检查时，非常重要和有用的差异 PH值和/或甚高频(VHF)。通过增加磁力 场和RS频率增加了十倍(3.3T和94 GHz)， 在具有不同g因子(或化学成分)的要素之间进行分割 班次)也将增加十倍。在.的情况下 自由基--这种分裂通常太小，不能用来解决 传统的EPR，在94 GHz分辨率的提高是相当大的 太戏剧化了。初步确定了平面pi-根的g-因子 通过O、N和S等杂原子的自旋密度，因为它们 具有比碳的自旋-轨道耦合常数大得多的自旋轨道耦合常数。 因此，人们可以很容易地区分半喹酮、半喹酮 亚胺和羟基苯并噻嗪的g-因子。W波段 人类神经黑色素样本的光谱显示出显著的差异 PH的作用和模型黑色素光谱的差异。它 应该强调的是，不能检测到这种一致的差异 在常规EPR频率(X波段)下。这是一个正在进行的项目。

The overall aim of the research is to determine the composition (especially the major monomeric units and their derivatives) and physical-chemical properties of neuromelanin (NM) and then to relate these properties to possible roles in pathophysiology, including the effects of the alteration of NM in aging and in degenerative diseases, especially Parkinson's Disease. Since NMs arise from different precursors than eumelanins, their EPR spectra should show subtle but crucially important and useful differences when examined at different pH's and/or very high frequency (VHF). By increasing the magnetic field and RS frequency by a factor of ten (3.3 T and 94 GHz), the splitting between features having different g-factors (or chemical shifts) will also increase by a factor of ten. In the case of free-radicals such splittings often are too small to resolve with conventional EPR, and the increase in resolution at 94 GHz is quite dramatic. The g-factor of planar pi-radicals is determined prima rily by the spin density on heteroatoms such as O, N, and S, since they have spin-orbit coupling constants much larger than that for carbon. Thus, one can readily distinguish between semiquinone, semiquinone imine, and hydroxybenzothiazine radicals from their g-factors. W-band spectra of human neuromelanin samples show marked differences as a function of pH and differences between spectra of model melanins. It should be stressed that no such consistent differences can be detected at conventional EPR frequencies (X-band). This is an ongoing project.