Leontakianakou Savvina, Grey Carl, Karlsson Eva Nordberg, Sardari Roya R R
Division of Biotechnology, Department of Chemistry, Lund University, PO Box 124, 22100, Lund, Sweden.
BMC Biotechnol. 2024 Dec 12;24(1):100. doi: 10.1186/s12896-024-00931-9.
Glucuronic acid (GlcA) is an abundant substituent in hardwood xylan, and it is often found in its methylated form as methyl glucuronic acid (MeGlcA). GlcA and MeGlcA are sugar acids, bound to the xylose backbone at position O-2, and their presence can affect the digestibility of the polymer. Currently, detection of released GlcA or MeGlcA from synthetic substrates such as pNP-glucuronic acid can be achieved with colorimetric assays, whereas analysis from natural substrates such as xylan is more complicated. High performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) with an isocratic elution profile has been proposed for quantification of uronic acids in acid-hydrolysed wood samples. However, achieving sufficient separation for comprehensive analysis of hardwood-related xylan components, particularly MeGlcA remains challenging with this methodology. This study offers modified protocols for improved separation by introducing gradient elution profiles to effectively separate hydrolysed hardwood-related compounds, including MeGlcA, and GlcA within a single analytical run. The method showed excellent reproducibility and a standard curve of MeGlcA assured first order linearity in a wide range of concentrations, making the method excellent for quantification.
葡萄糖醛酸（GlcA）是阔叶木聚糖中一种丰富的取代基，并且它常常以甲基葡萄糖醛酸（MeGlcA）的甲基化形式存在。GlcA和MeGlcA是糖酸，在O-2位与木糖主链相连，它们的存在会影响聚合物的消化率。目前，使用比色法可以检测从合成底物如对硝基苯葡萄糖醛酸中释放的GlcA或MeGlcA，而从天然底物如木聚糖进行分析则更为复杂。有人提出采用等度洗脱模式的高效阴离子交换色谱-脉冲安培检测法（HPAEC-PAD）来定量分析酸水解木材样品中的糖醛酸。然而，用这种方法实现对阔叶木相关木聚糖成分（特别是MeGlcA）进行全面分析的充分分离仍然具有挑战性。本研究提供了改进的方案，通过引入梯度洗脱模式来改善分离效果，从而在一次分析运行中有效分离水解后的阔叶木相关化合物，包括MeGlcA和GlcA。该方法具有出色的重现性，MeGlcA的标准曲线在很宽的浓度范围内保证了一阶线性，使得该方法非常适合定量分析。
