硫氧还蛋白及其L79Y变体酶切后片段自身重新结合为同源二聚体的稳定性和动力学研究  

COMPARISON OF THE STABILITY AND KINETICS OF THE SELF-ASSEMBLED THIOREDOXIN FRAGMENTS WITH IT\'S L79Y MUTANT

作　　者：王建华[1] 海尔汗[2] 冶杰慧[2] 谢红霞[1] 

机构地区：[1]内蒙古医学院药学系,内蒙古呼和浩特010059 [2]内蒙古工业大学化工学院

出　　处：《内蒙古医学院学报》2002年第3期148-152,共5页Acta Academiae Medicinae Neimongol

摘　　要：目的 :进一步研究蛋白质酶切后重新结合成同源二聚体时功能区域中残基的影响。方法 :在研究了野生硫氧还蛋白、硫氧还蛋白 L79F变体、硫氧还蛋白 L79K变体的基础上 ,本文选用野生硫氧还蛋白 (TRX)和硫氧还蛋白 L79Y变体分别做为研究对象 ,使硫氧还蛋白和硫氧还蛋白 L79Y变体分别进行酶切。结果 :酶切后得到的两组片段。以 N片段 (1 -73 )和 C片段 (74-1 0 8)再重新进行结合形成同源二聚体。比较排 79位的残基的改变对 N片段 (1 -73 )和 C片段 (74-1 0 8)重新结合成同源二聚体的影响。结论 :1 .TRX中处于 β折叠状态的β4 区域 (P76,T77,L78,L79,L80 ,F81和 K82 )中 79位的残基由非极性改变为带有羟基的极性残基使 N片段和C片段重新聚合成非共价同源二聚体的速率常数有所增大 ,说明聚合较易进行。 2 .这一变化使酶切后的 N片段和 C片段重新形成的同源二聚体的稳定性大大降低。Objective: The stability and kinetics of self-assembled complex may be effected by the size, charge and polarity of a residue in a α/β domain. Methods: We choose L79Y mutant of thioredoxin in which at position 79 leucine is substituted by tyrosine. In this mutant, the residue\'s polarity is stronger than wild type TRX. After we compared the stability of the complex of the re-assembled N fragment and C fragment of wild type TRX with the complex of the re-assembled N fragment and C fragment of L79Y mutant and the kinetics of these two complexes. Results: (1) The stability of re-assembled complex which N fragment (1-73) combines with C fragment from L79Y is much more unstable than the complex from the wild type thioredoxin. (2) The kinetics of the re-assembly complex of the L79Y is different from that of wild type thioredoxin. Conclusion: The rate constant of the re-assembly of the L79Y mutant\'s N fragment and C fragment is much higher than that of the wild type thioredoxin.\;

关 键 词：硫氧还蛋白 L79Y变体酶 同源二聚体 稳定性 动力学 离解常数 

分 类 号：Q51[生物学—生物化学]