过氧化氢酶Ⅰ结构延伸突变改善酶热稳定性的初步研究

Primary Studies on the Improvement of Enzyme Thermostability by Elongation Mutation of Catalase Ⅰ

嗜热脂肪芽孢杆菌过氧化氢酶Ⅰ及其取代突变酶８８（２５）的延伸突变是指在酶蛋白的Ｃ末端上连接一段随机肽链，从而改变了酶蛋白的结构．研究结果表明，这种延伸突变的方法非常有效地提高了酶的热稳定性，并且随机肽链的疏水性与其对应的延伸突变体酶的热稳定性呈现一定的负相关性，即随机肽链的疏水性越高。

The connection of random peptide at C terminal of catalase Ⅰ from Bacillus stearothermophilus and its derivative mutant 88(25) (108 Ile→Thr,130 Asp→Asn and 222 Ile→Thr)to expand the sequence space by increasing their dimensions has been used to enhance the thermostability of catalase Ⅰ and its mutant 88(25).The amino acid sequences of random peptides were identified by translating nucleotide squences.The elongation approach has been effective for improving enzyme thermostability.It was tried to find the effects of molecular attributions of a random peptide,such as hydrophobicity,charge,specific volumn etc ,on enzyme thermostability.An intriguing insight was described that the random peptides’ hydrophobicity on the thermostability of elongation mutants demonstrated a certain statistical patten,a negative correlation is observed such that the higher hydrophobicity of a random peptide resulted in lower thermostability of an elongation mutant enzyme.