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

描述（由申请人提供）：美国有超过1600万人患有糖尿病。这些病例中近95%是2型糖尿病。2型糖尿病是过去几十年来糖尿病病例迅速增加的原因，并与胰岛素抵抗有关。身体正常产生胰岛素（至少在开始时）;然而，胰岛素信号没有正确地传递到细胞中。任何可能增强胰岛素敏感性的机制在治疗2型糖尿病和其他与胰岛素抵抗相关的病症（高血压、心血管疾病等）中具有潜在价值。已提出铬在胰岛素信号传导中起作用，并且药理学剂量的铬在糖尿病患者和模型动物中具有有益作用。在分子水平上理解铬在胰岛素信号增强中的作用，可能会导致开发以铬为基础的治疗糖尿病的药物。NCCAM最近通过资助项目“铬作为2型糖尿病和糖耐量受损的辅助治疗”（PA-01-114）认识到铬的重要性。阐明铬在增强胰岛素敏感性中的作用受到一些实验问题的阻碍。首先，铬在体内分布的途径尚未完全阐明。组织如肝脏和肾脏中的铬通过寡肽低分子量铬结合物质（LMWCr）或铬调蛋白结合，已提出其通过与胰岛素受体相互作用而具有增强胰岛素信号传导的作用。然而，虽然LMWCR已被很好地表征光谱和磁性，寡肽已被证明难以测序和生物基质中检测。这项工作的具体目标是1）开发和利用质谱法分析含铬大分子的程序，最值得注意的是高酸性肽及其铬络合物，包括其片段化途径，2）将这些知识应用于测序LMWCr（铬调蛋白）和相关的含铬肽，和3）确定尿的低摩尔质量铬结合组分的性质，假设为LMWCr。该方法将采用两种先进的质谱方法：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).