豇豆几丁质酶N端序列测定及与其它植物的比较

通过自动 Edman降解程序 ,测定了经诱导、纯化的豇豆几丁质酶 N端 1 0个氨基酸的序列 ,并将该序列与其它植物几丁质酶 N端相应部分的氨基酸序列进行了比较分析。结果表明 ,该豇豆 ( Vigna sesquipedalis)几丁质酶 N端 1 0个氨基酸的序列为 EQCGSQAGGA,与 类几丁质酶同一部分同感序列同源性高达 1 0 0 % ;而与 、 及 类几丁质酶的相应序列均无同源性。结合考虑此酶的等电点 ( 8.3)及分子量 ( 33k D) ,可推测该豇豆几丁质酶属于 类几丁质酶。其 N端序列的高度保守性提示 ,该段序列可作为 类几丁质酶的一段主要特征序列 ,并可据其合成核酸探针 ,以分离、克隆其它 类几丁质酶编码基因。

Determination of the N-terminal amino acid sequence of a chitinase from Vigna sesquipedalis and its comparison with those of the same regions from other plant chitinases

The sequence of ten N-terminal amino acids was determined by automatic Edman degradation, for an induced and purified chitinase from Vigna sesquipedalis, and compared with those of the same regions of other plant chitinases. The results indicated that the first ten N-terminal amino acids for the chitinase from V. sesquipedalis were sequenced in EQCGSQAGGA. The sequene shared a 100% homology with the consensus sequence of the other sequenced chitinases class Ⅰ, however, presented no homology to the sequences of ten N-terminal amino acids from the chitinases of class Ⅱ, class Ⅲ and class Ⅳ, respectively. With its isoelectric point (8.3) and molecular weight (33kD), it was deducible that the chitinase from V. sesquipedalis was one of the chitinases class Ⅰ. The fact that the first ten N-terminal amino acids were very high conservative within the chitinases class Ⅰ suggested that the sequence could serve as a main characteristic sequence for class Ⅰ. And some oligo-nucleotide probes, synthetized on the basis of it, could be used to isolate and clone the genes encoding the chitinases of class Ⅰ.