Conformational changes in the catalytic region are responsible for heat-induced activation of hyperthermophilic homoserine dehydrogenase

Fig. 2: Effect of pH on enzyme activity. The activity of the immature (white bar) and mature enzymes (grey bar) were assayed in 100 mM acetate (pHs4.5, 5,0 and 5.5), MES (pHs 5.5, 6.0 and 6.5), HEPES (pHs 6.5, 7.0, 7.5 and 8.0), Tris (pHs 8.0, 8.5 and 9.0), Glycine (pHs 9.0, 9.5 and 10.0) or CAPS (pHs 10.0, 10.5, 11.0 and 11.5) at 303 K. Fig. 3: Effect of temperature on enzyme activity. The activity of the immature (white bar) and mature enzymes (grey bar) were assayed in 100 mM tris (pH 8.0) at various temperatures. Supplementary Figure 1. pH stabilities of the enzymes. The activity of the immature (white bar) and mature enzymes (grey bar) were incubated in 100 mM acetate (pHs 4.5, 5,0 and 5.5), MES (pHs 5.5, 6.0 and 6.5), HEPES (pHs 6.5, 7.0, 7.5 and 8.0), Tris (pHs 8.0, 8.5 and 9.0), Glycine (pHs 9.0, 9.5 and 10.0) or CAPS (pHs 10.0, 10.5, 11.0 and 11.5) at 353 K for 10 min and the residual activities were assayed in 100 mM Tris pH 8.0 at 303 K.

图2：pH对酶活性的影响。于303开尔文条件下，分别在100 mM乙酸盐（acetate，pH值4.5、5.0、5.5）、吗啉乙磺酸（MES，pH值5.5、6.0、6.5）、4-羟乙基哌嗪乙磺酸（HEPES，pH值6.5、7.0、7.5、8.0）、三羟甲基氨基甲烷（Tris，pH值8.0、8.5、9.0）、甘氨酸（Glycine，pH值9.0、9.5、10.0）或3-环己胺基丙磺酸（CAPS，pH值10.0、10.5、11.0、11.5）缓冲液中，测定未成熟酶（白色柱）与成熟酶（灰色柱）的活性。
图3：温度对酶活性的影响。于不同温度条件下，在100 mM三羟甲基氨基甲烷（Tris，pH值8.0）缓冲液中，测定未成熟酶与成熟酶的活性。
补充图1：酶的pH稳定性。将未成熟酶与成熟酶于353开尔文下，在100 mM乙酸盐（acetate，pH值4.5、5.0、5.5）、吗啉乙磺酸（MES，pH值5.5、6.0、6.5）、4-羟乙基哌嗪乙磺酸（HEPES，pH值6.5、7.0、7.5、8.0）、三羟甲基氨基甲烷（Tris，pH值8.0、8.5、9.0）、甘氨酸（Glycine，pH值9.0、9.5、10.0）或3-环己胺基丙磺酸（CAPS，pH值10.0、10.5、11.0、11.5）缓冲液中孵育10分钟，随后在100 mM三羟甲基氨基甲烷（Tris，pH值8.0）缓冲液、303开尔文条件下测定其残余酶活性。