中文摘要：

建立了一种简便快捷的甘露糖醛酸C-5差向异构酶活性的测定方法。研究发现相同分子质量的聚甘露糖醛酸和聚古罗糖醛酸与苯酚硫酸试剂反应后显色程度不同，以此可以用来测定β-D-甘露糖醛酸／α—L-古罗糖醛酸（M／G）值的变化，从而计算甘露糖醛酸C-5差向异构酶的活性。利用本方法测定了已知结构的褐藻胶片断的M／G比，其结果与传统的^1H—NMR测定值基本一致。

英文摘要：

A simple and convenient method for the C-5-mannuronan epimeration assay was established in this study. The color intensity of poly-mannuronate was markedly different from that of poly-guluronate when they reacted with sulfate-phenol. So the activity of C-5-mannuronan epimerase can be determined using the sulfate-phenol method by comparing the absorption of the alginate substrate before and after the enzymatic reaction. The M/G ratio of alginate fragments with known structure was detected by Sulfate-phenol method, and the result was almost the same as the value by ^1 H-NMR.