Elucidating the properties of low-molecular-weight chromuim-binding substance

描述(申请人提供)：美国有1600多万人患有糖尿病。这些病例中近95%是2型糖尿病。2型糖尿病是过去几十年糖尿病病例迅速增加的原因，并与胰岛素抵抗有关。人体正常地(至少在一开始)产生胰岛素；然而，胰岛素信号没有正确地传递到细胞中。任何可以增强胰岛素敏感性的机制在治疗2型糖尿病症状和其他与胰岛素抵抗相关的疾病(高血压、心血管疾病等)方面都有潜在的价值。铬已被认为在胰岛素信号转导中发挥作用，药理剂量的铬对糖尿病患者和模型动物有有益的影响。在分子水平上了解铬在胰岛素信号增强中的作用可能会导致开发治疗糖尿病的含铬药物。铬的重要性最近被NCCAM通过资助项目“铬作为2型糖尿病和糖耐量受损的辅助治疗”(PA-01-114)认识到。一些实验问题阻碍了阐明铬在增强胰岛素敏感性中的作用。首先，铬在体内的分布途径尚未完全阐明。肝脏和肾脏等组织中的铬被低分子量铬结合物质(LMWCR)或铬调素结合，它被认为通过与胰岛素受体相互作用而增强胰岛素信号转导。然而，虽然LMWCR已经得到了很好的光谱和磁性表征，但事实证明，这种寡肽很难在生物基质中进行测序和检测。这项工作的具体目标是1)开发和利用质谱仪分析含铬大分子，最显著的是高酸性多肽及其铬络合物及其裂解途径，2)将这一知识应用于测序LMWCR(嗜铬调素)和相关的含铬多肽，以及3)确定尿中低摩尔质量铬结合组分的性质，推测为低相对分子质量铬结合组分。该方法将采用两种先进的质谱学方法：电喷雾电离傅里叶变换离子回旋共振(ESI/FT-ICR)和基质辅助激光解吸电离飞行时间(MALDI/TOF)。

DESCRIPTION (provided by applicant): Over 16 million people in the US have diabetes mellitus. Nearly 95% of these cases are of type 2 diabetes. Type 2 diabetes is responsible for the rapid increase in diabetes cases over the last few decades and is associated with insulin resistance. The body produces insulin normally (at least at first); however, the insulin signal is not properly transmitted into cells. Any mechanism by which insulin sensitivity might be enhanced has potential value in the treatment of symptoms of type 2 diabetes and other conditions related to insulin resistance (hypertension, cardiovascular disease, etc.). Chromium has been proposed to play a role in insulin signaling, and pharmacological doses of chromium have beneficial effects in diabetic patients and model animals. Understanding at a molecular level the role of chromium in insulin-signaling enhancement could lead to development of chromium-bsaed drugs for the treatment of diabetes. The importance of chromium was recently recognized by NCCAM through the funding program "Chromium as adjuvant therapy for type 2 diabetes and impaired glucose tolerance" (PA-01-114). Elucidating the role of chromium in enhancing insulin sensitivity has been hindered by a couple of experimental problems. First, the pathway by which chromium is distributed in the body has not been completely elucidated. Chromium in tissues such as liver and kidney is bound by the oligopeptide low-molecular weight chromium-binding substance (LMWCr) or chromodulin, which has been proposed to have a role in enhancing insulin signaling by interacting with insulin receptor. However, while LMWCR has been well characterized spectroscopically and magnetically, the oligopeptide has proven difficult to sequence and detect in biological matrices. The specific aims of this work are 1) to develop and utilize procedures for analyzing chromium-containing macromolecules by mass spectrometry, most notably highly acidic peptides and their Cr complexes including their fragmentation pathways, 2) to apply this knowledge to sequencing LMWCr (chromodulin) and related chromium-containing peptides, and 3) to determine the nature of the low-molar mass chromium-binding component of urine, postulated to be LMWCr. The approach will employ two advancing methodologies in mass spectrometry: electrospray ionization Fourier transform ion cyclotron resonance (ESI/FT-ICR) and matrix-assisted laser desorption ionization time-of-flight (MALDI/TOF).