Hattan Christopher M, Kerns Robert J
Division of Medicinal and Natural Products Chemistry, University of Iowa, Iowa City, IA 52242, United States.
Carbohydr Res. 2007 Dec 10;342(17):2664-9. doi: 10.1016/j.carres.2007.08.004. Epub 2007 Aug 23.
The carbazole assay is commonly employed to quantify heparin and other uronic acid-containing polysaccharides. Heparin-derived standard curves are often employed to quantify solutions of various natural and unnatural heparin structures that have different levels of sulfate substitution, different levels of N-sulfo and N-acetyl groups, and other structural changes as a consequence of reducing molecular weight. Recent studies in our laboratory have focused on chemically modified heparin derivatives comprised of structurally diverse N-acyl moieties substituted into heparin in place of N-sulfo groups. We report here that although differing degrees of 2-N-sulfo-, 2-N-acetyl- or 2-amino-d-glucosamine residues within heparin do not affect signal intensity in the carbazole assay, replacing N-sulfo groups in heparin with structurally diverse N-acyl moieties affords products that display significant variation in the assay. The structure of different N-acyl groups, and to a lesser extent the degree of N-acylation by individual N-acyl groups, is shown to variably alter signal intensity in the carbazole assay even though content and structure of uronic acid residues is unaltered.
咔唑测定法通常用于定量肝素和其他含糖醛酸的多糖。肝素衍生的标准曲线常被用于定量各种天然和非天然肝素结构的溶液，这些结构具有不同程度的硫酸化取代、不同水平的N-磺基和N-乙酰基，以及由于分子量降低而导致的其他结构变化。我们实验室最近的研究集中在化学修饰的肝素衍生物上，这些衍生物由结构多样的N-酰基部分取代肝素中的N-磺基组成。我们在此报告，尽管肝素中不同程度的2-N-磺基、2-N-乙酰基或2-氨基-D-葡萄糖胺残基不会影响咔唑测定法中的信号强度，但用结构多样的N-酰基部分取代肝素中的N-磺基会得到在该测定法中显示出显著差异的产物。结果表明，即使糖醛酸残基的含量和结构未改变，不同N-酰基的结构以及单个N-酰基的N-酰化程度在较小程度上也会可变地改变咔唑测定法中的信号强度。
