| Budget Amount *help |
¥16,440,000 (Direct Cost: ¥14,700,000、Indirect Cost: ¥1,740,000)
Fiscal Year 2007: ¥7,540,000 (Direct Cost: ¥5,800,000、Indirect Cost: ¥1,740,000)
Fiscal Year 2006: ¥4,300,000 (Direct Cost: ¥4,300,000)
Fiscal Year 2005: ¥4,600,000 (Direct Cost: ¥4,600,000)
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| Research Abstract |
Mass spectrometry (MS) is an important analytical tool that provides information about molecular weight. However MS is not only for the simple analysis of molecular weights, but it is in general one of the most sensitive detection methods for biological, chemical, pharmaceutical, and environmental analysis. Detection by MS consists of the steps of introduction into the mass spectrometer ionization, separation, and detection of a target molecule. Nowadays, several ionization and separation methods exist. Among the ionization methods, electrospray ionization (ESI), and matrix-assisted laser desorption/ionization (MALDI) became most popular. However the further development of new ionization methods is required for more sensitive and more accurate MS measurements.
In this investigation, we designed and synthesized MS probes (labeling reagents) for different kinds of ions and molecules. The MS probes for proteins are designed to enable the detection of tag molecules, instead of the proteins
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themselves. The molecular weight of the tag molecules is designed to be within the range of 100-1000 mass units, allowing the continuous detection of proteins and other molecules without changing the settings of the MS instrument, since this is the most suitable mass range for the detection of the majority of other target small molecules or metal cations labeled with mass probes. The labeling of the proteins with the MS probes occurs via an intermediate antibody, because a protein sample has a number of reactive moieties, and is thus difficult to be labeled by a chemical reaction.
Metal cations are essential targets in clinical, biological, and environmental samples and are desirably detected together with other small molecules. Normally, metal cations exist as a mixture, and their identification by ESI-MS is difficult because they are detected as the mass values divided by their valencies. In addition, the separation of different metal ions by LC before sample introduction is difficult. Mass probes are a powerful tool for the detection by ESI-MS of a singly charged molecule within the appropriate range of molecular size. We have developed mass probes that nonspecifically bind to different metal cations to form a charged-chelate complex, which enables the detection of ions with consecutive measurements by a mass spectrometer for liquid samples. Less
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