Draborg H, Kauppinen S, Dalbøge H, Christgau S
GeneExpress, Novo Nordisk A/S, Copenhagen O, Denmark.
Biochem Mol Biol Int. 1995 Jul;36(4):781-91.
The synthetic exochitinase substrate 4-methylumbelliferyl N-acetylglucosamine was used to identify seven full-length exochitinase-encoding cDNAs from a Trichoderma harzianum cDNA library by expression in yeast. The cDNA clones represented transcripts of two exochitinase genes, designated as exc1 and exc2, which cross-hybridized under moderate stringency conditions in genomic Southern blots. The exc1 cDNA encodes a 578 amino acid polypeptide showing 72% similarity to the exc2-encoded 602-residue polypeptide. The deduced exochitinase amino acid sequences were found to be homologous with mammalian and fungal hexosaminidases as well as a bacterial chitobiosidase. The substrate specificity of the recombinant enzymes expressed in S. cerevisiae indicates that the enzymes are N-acetylglucosaminidases releasing single N-acetylglucosamine residues from the non-reducing end of the chitin substrate.
合成的外切几丁质酶底物4-甲基伞形酮基N-乙酰葡糖胺被用于通过在酵母中表达，从哈茨木霉cDNA文库中鉴定出7个全长外切几丁质酶编码cDNA。这些cDNA克隆代表了两个外切几丁质酶基因的转录本，命名为exc1和exc2，它们在基因组Southern印迹中在中等严格条件下交叉杂交。exc1 cDNA编码一个578个氨基酸的多肽，与exc2编码的602个残基的多肽显示出72%的相似性。推导的外切几丁质酶氨基酸序列与哺乳动物和真菌的氨基己糖苷酶以及一种细菌壳二糖酶同源。在酿酒酵母中表达的重组酶的底物特异性表明，这些酶是从几丁质底物的非还原端释放单个N-乙酰葡糖胺残基的N-乙酰葡糖胺酶。
