木糖还原酶（XR, EC 1.1.1.21）是真菌微生物代谢木糖的关键酶之一。本文以米曲霉基因组DNA为模板，克隆木糖还原酶基因（xr，GenBank登录号：FJ957890.1），并对XR的序列、系统进化树、理化性质及蛋白结构等进行生物信息学分析。结果表明： xr基因序列长1449 bp，其中开放阅读框长960 bp，编码319个氨基酸，蛋白质分子质量35.9 kDa，等电点为5.78；米曲霉XR与其他菌种XR有较高的同一性，含有醛酮还原酶家族的两个指纹结构和一个参与辅酶结合活性位点指纹结构，以及醛酮还原酶家族典型的（β/α）8 TIM桶结构，说明米曲霉XR属于醛酮还原酶家族。

Xylose reductase (XR, EC 1.1.1.21) is one of the key enzymes of xylose metabolism for the eukaryotic microorganism. The XR gene (xr) from Aspergillus oryzae was amplified by PCR and cloned (GenBank accession number: FJ957890.1). Then the similarity of amino acid sequences, phylogenetic trees, physic-chemical property and protein structure were analyzed bioinformatically. Sequence analysis reveals that the length of xr is 1449 bp, which contains 960 bp open reading frame encoding 319 amino acids. A. oryzae XR has high sequence identity with other strain XR. The presence of two aldo-keto reductase family signatures, a putative coenzyme-binding active site signature and a typical parallel beta-8/alpha-8-barrel tertiary structure suggests that XR is a member of aldo-keto reductase superfamily. The obtained information lays the basis for the expression of XR and further research on xylose metabolic regulation and widely industrial application of A. oryzae.