Stearman R S, Frankel A D, Freire E, Liu B S, Pabo C O
Department of Biophysics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Biochemistry. 1988 Sep 20;27(19):7571-4. doi: 10.1021/bi00419a059.
We have combined three mutations previously shown to stabilize lambda repressor against thermal denaturation. Two of these mutations are in helix 3, where Gly-46 and Gly-48 have been replaced by alanines [Hecht, M. H., et al. (1986) Proteins: Struct., Funct., Genet. 1, 43-46]. The other mutation, which replaces Tyr-88 with cysteine, allows the protein to form an intersubunit disulfide bond [Sauer, R. T., et al. (1986) Biochemistry 25, 5992-5998]. Calorimetric measurements show that the two alanine substitutions stabilize repressor by about 8 degrees C, that the disulfide bond stabilizes repressor by about 8 degrees C, and that the triple mutant is 16 degrees C more stable than wild-type repressor.
我们将先前已证明能使λ阻遏蛋白稳定以抵抗热变性的三种突变组合在一起。其中两种突变位于螺旋3，甘氨酸-46和甘氨酸-48被丙氨酸取代[赫克特，M. H.等人（1986年）《蛋白质：结构、功能、遗传学》1，43 - 46]。另一种突变是将酪氨酸-88替换为半胱氨酸，使该蛋白质能够形成亚基间二硫键[索尔，R. T.等人（1986年）《生物化学》25，5992 - 5998]。量热测量表明，两个丙氨酸取代使阻遏蛋白稳定约8摄氏度，二硫键使阻遏蛋白稳定约8摄氏度，并且三重突变体比野生型阻遏蛋白稳定16摄氏度。
