甘露聚糖酶Man1602中的色氨酸修饰及其突变体性质的研究

Studies on Modifying Tryptophan Residues of Man1602 and Researching Characteristics of Site-Directed mutant Man1602

摘要:

为了揭示色氨酸残基与Man1602酶活力的关系，提高Man1602的表达量，笔者通过研究色氨酸专一化学修饰剂与甘露聚糖酶Man1602的反应，同时根据甘露聚糖酶Man1602的序列比对结果，推测色氨酸残基与酶活的关系，对保守位点的色氨酸进行定点突变，检测各突变体酶的活力变化。结果表明，色氨酸为甘露聚糖酶Man1602的活性必需氨基酸，其中W196和W199位点的突变导致酶活几乎完全丧失，可以推断W196和W199为活性中心的氨基酸，W198也具有较高保守性，但对其突变并未造成酶的完全失活，推断W198是维持活性中心疏水性的重要氨基酸。

Abstract:

In order to reveal the relationship between the tryptophan residue and the activity of Man1602，the expression of Man1602 was increased，the authors studied the reaction of tryptophan-specific chemical modifier with mannanase Man1602，at the same time，according to the sequence alignment results of Man1602，the relationship between tryptophan residues and enzyme activity was deduced，the fixed position of tryptophan was fixed，and the activity of the mutant was detected. The results showed that tryptophan is the active essential amino acid of Man1602，in which the mutation of W196 and W199 sites leads to almost complete loss of enzyme activity. It can be inferred that W196 and W199 are the active centers of amino acids. W198 also has a high conservation，but its mutation did not cause the complete inactivation of the enzyme so it was concluded that W198 was an important residue to sustain the hydrophobic constant of the enzyme active site.