论文部分内容阅读
本文研究了单点突变Q92P对酶活性,稳定性以及折叠途径的影响.尽管该位点不直接参与底物催化,但92位氨基酸的突变对酶的活性,稳定性以及折叠过程产生了重大的影响.该突变的酶活性有较大程度的降低,通过模拟发现该位点的氢键网被破坏.而且光谱实验表明该突变导致更多被掩埋的色氨酸暴露于周边环境,但并没有较大的影响到二级结构和疏水面暴露程度.在对抗化学品诱导的去折叠程度上,相比于野生型蛋白,该突变蛋白稳定性较差.通过吉布斯自由能的计算发现该突变位点轻微的降低了中间体的稳定性,但相对更大的影响了天然态的稳定性,天然态至中间体的能量大约为野生型的20%左右.该结果有组于解释在折叠过程中倾向于聚沉的中间体的存在,该中间体的存在影响了正常的折叠路径.该实验表明92位氨基酸对人碳酸酐酶Ⅱ的活性和稳定性很重要.
In this paper, the effect of single point mutation Q92P on enzyme activity, stability and folding pathway was investigated.Although the site was not directly involved in the substrate catalysis, the amino acid mutation at position 92 had a significant effect on enzyme activity, stability and folding process Affected the enzyme activity of this mutation to a greater extent, and found that the hydrogen bond network of the site was destroyed by the simulation.Furthermore, spectral experiments showed that the mutation resulted in more buried tryptophan exposed to the surrounding environment, but no Greatly affect the degree of secondary structure and hydrophobic surface exposure in the degree of resistance to chemical-induced defoliation, compared to the wild-type protein, the mutant protein stability is poor.From Gibbs free energy calculations found that the The site of mutation slightly reduced the stability of the intermediate, but affected the stability of the natural state relatively more, the energy of the natural state to the intermediate was about 20% The presence of this intermediate affected the normal folding pathways, suggesting that the 92 amino acids are important for the activity and stability of human carbonic anhydrase II.