標識されていない炭水化物における (1) H ホモ核スケーラ結合の決定
Catherine Zwahlen1, Sébastien J F Vincent
1Université de Lausanne, Institut de Chimie Organique, CH-1015 Lausanne, Switzerland.
Journal of the American Chemical Society
|June 13, 2002
まとめ
この研究は,炭水化物の重要な構造パラメータを測定するための新しいNMR実験を導入しています. この方法は,ポリサッカライドやグリコプロテインなどの大きなバイオ分子を分析する際の限界を克服します.
科学分野:
- 炭水化物化学 炭水化物の化学
- 構造生物学 構造生物学とは
- 核磁共振 (NMR) スペクトロスコピー
背景:
- 炭水化物の構造の解明は,結晶化の困難と現在のNMR分析の限界のために困難です.
- (1) H同核スカラー結合を決定するための既存の方法は,ポリサッカリドやグリコタンパク質などの大きなバイオ分子では不十分である.
研究 の 目的:
- 標識されていない炭水化物における内循環性 (1) H ホモ核スカラー結合 ((3) J(HH)) を決定するための新しいNMR実験を提示する.
- 開発されたNMR技術を使用して,大型ポリサッカリドの交互に相関する二極二極リラクゼーション率を測定する.
主な方法:
- (1) H同核スカラー結合の決定のための新しいNMR実験の開発と応用.
- エンドサイクリックカップリング定数と相互相関の二極二極緩解率の測定.
主要な成果:
- NMR実験では,炭水化物の内循環性 (1) H ホモ核スケーラカップリングを成功裏に決定しました.
- すべての内循環性同核結合定数は,乳糖,ディサカリドモデルのために測定されました.
- この方法は,Streptococcus thermophilus Sfi39の2MDaの細菌のポリサッカリドに適用され,構造的結合情報を得ました.
結論:
- 提示されたNMR実験は,炭水化物の構造分析,特に大きく,ラベルが付けられていないバイオ分子に著しく進歩します.
- このテクニックは,重要なスケラーカップリングデータを提供し,ポリサッカライドとグリコタンパク質の構造解像度を改善します.
- この研究は,細菌のポリサッカリドを含む複雑な天然製品に対する方法の適用性を実証しています.
関連する概念動画
Degree of Unsaturation
The degree of unsaturation (U), or index of hydrogen deficiency (IHD), is defined as the difference in the number of pairs of hydrogen atoms between the compound and the acyclic alkane with the same number of carbon atoms. Each double bond or ring costs two hydrogen atoms compared to a saturated analog and results in one degree of unsaturation.
The degree of unsaturation for hydrocarbons is U = (2C + 2 − H) / 2, where C is the number of carbon atoms and H is the number of hydrogen atoms.
For...
The degree of unsaturation for hydrocarbons is U = (2C + 2 − H) / 2, where C is the number of carbon atoms and H is the number of hydrogen atoms.
For...
2D NMR: Heteronuclear Single-Quantum Correlation Spectroscopy (HSQC)
Heteronuclear single-quantum correlation spectroscopy (HSQC) is a 2D NMR technique that reveals one-bond correlations between hydrogen and a heteronucleus. The HSQC experiment is similar to the heteronuclear correlation experiment (HETCOR) but is more sensitive. In the HSQC spectrum, the proton chemical shift is plotted on the horizontal F2 axis, while the 13C chemical shift is plotted on the vertical F1 axis. The corresponding proton and 13C spectra are also shown. The HSQC contour plot does...
High-Resolution Mass Spectrometry (HRMS)
The resolution of a mass spectrometer depends on the efficiency of separating ions with different ion masses. The mass of an atom is approximated to the sum of the masses of protons and neutrons inside, considering the masses of protons and neutrons as equal. However, the masses of the proton (1.6726 × 10−24 g) and neutron (1.6749 × 10−24 g) are not truly equal. There is a minor error in the expression of atomic masses relative to the simplest atom of hydrogen. For example, the mass of helium...
¹³C NMR: ¹H–¹³C Decoupling
The probability of having two carbon-13 atoms next to each other is negligible because of the low natural abundance of carbon-13. Consequently, peak splitting due to carbon-carbon spin-spin coupling is not observed in spectra. However, protons up to three sigma bonds away split the carbon signal according to the n+1 rule, resulting in complicated spectra.
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
Mass Spectrum: Interpretation
An unknown compound can be established by identifying the molecular ion peak in the mass spectrum. The molecular ion peak is often weak or absent due to the predominance of fragmentation in high-energy electron beams. In such cases, a soft-energy electron beam can be used to scan the spectrum to enhance the intensity of the molecular ion peak. Additionally, chemical ionization, field ionization, and desorption ionization spectra are used to obtain a relatively intense molecular ion peak.To...
2D NMR: Overview of Heteronuclear Correlation Techniques
Heteronuclear correlation spectroscopy is an analytical technique that investigates the coupling between different types of nuclei, often a proton and an X-nucleus, such as carbon-13 or nitrogen-15. This method is commonly used in nuclear magnetic resonance (NMR) spectroscopy to gain insights into complex chemical compounds' structural and compositional aspects. A typical heteronuclear correlation spectrum displays X-nucleus chemical shifts on one axis and a proton spectrum on the other axis.


