来源于Aspergillus candidus的乳糖酶基因的克隆及序列分析

从一株产乳糖酶的亮白曲霉（Aspergillus candidus)中克隆到了乳糖酶基因组DNA及cDNA序列（EMBL AC－CESSION No.AJ431643)，序列分析表明，乳糖酶基因组DNA序列长3458bp，其中含有8个内含子，cDNA编码区长3015bp，共编码1005个氨基酸，前19个氨基酸为信号肽序列，氨基酸序列中共含有11个潜在的糖基化位点。将此基因在不同来源的乳糖酶基因序列进行比较发现，该基因与绝大多数乳糖酶基因同源性较低。虽与米曲霉ATCC20423的乳糖酶序列同源性较高，但其在酶学性质上更优于后者，亮白曲霉的乳糖酶基因可能是一个具有更广阔的生产应用前景的新基因。

Cloning and Sequencing of Lactase Gene from Aspergillus candidus

Genomic DNA and cDNA sequences of lactase from Aspergillus candidus were cloned. Sequences analysis revealed that the genomic DNA was 3458bp containing eight introns, cDNA was 3015bp and encoding a polypeptide of 1005 amino acid residues. Signal peptide was 19 amino acid residues, eleven potential N-glycosylation sites were assumed. Comparing the gene cDNA and amino acid sequences with other lactase sequences from various sources, it showed a very low homology with most of other sequences. Although the gene had a higher homology to Aspergillus oryzae lactase sequence, characterization of both enzymes exhibited obvious difference. The gene from Aspergillus candidus was a promising new gene for food industry.