Paulsen K E, Stankovich M T, Stockman B J, Markley J L
Department of Chemistry, University of Minnesota, Minneapolis 55455.
Arch Biochem Biophys. 1990 Jul;280(1):68-73. doi: 10.1016/0003-9861(90)90519-5.
We report here on the spectrophotometric and electrochemical properties of the flavodoxin from Anabaena 7120 and compare these properties with those of flavodoxins that have been studied previously. Molar absorption coefficients have been determined for all three oxidation states of this protein, at various wavelengths. For oxidized flavodoxin, molar absorption coefficients for the absorption maxima at 464 and 373 nm were 9200 and 8500 M-1 cm-1, respectively. Reduction by the first electron produced a neutral blue semiquinone which exhibited an absorption maximum at 575 nm. The molar absorption coefficients at 575 nm were 200 M-1 cm-1 for the oxidized form, 5100 M-1 cm-1 for the semiquinone form, and 250 M-1 cm-1 for the hydroquinone form. Redox potentials have been determined, in the pH range of 6.0 to 8.5, for both electron transfers. At pH 7.0, the midpoint potential values for the first and second electron transfers were -0.196 and -0.425 V, respectively. We determined that the first electron transfer is pH dependent and that a proton transfer accompanies this one electron transfer. It was also determined that the second electron transfer is pH independent in the pH range of 6.0 to 8.5.
我们在此报告了鱼腥藻7120黄素氧还蛋白的分光光度和电化学性质，并将这些性质与先前研究过的黄素氧还蛋白的性质进行了比较。已测定了该蛋白质在不同波长下三种氧化态的摩尔吸收系数。对于氧化型黄素氧还蛋白，在464和373nm处吸收最大值的摩尔吸收系数分别为9200和8500 M-1 cm-1。第一个电子的还原产生了一种中性蓝色半醌，其在575nm处有最大吸收。在575nm处，氧化型的摩尔吸收系数为200 M-1 cm-1，半醌型为5100 M-1 cm-1，对苯二酚型为250 M-1 cm-1。已测定了在pH 6.0至8.5范围内两种电子转移的氧化还原电位。在pH 7.0时，第一次和第二次电子转移的中点电位值分别为-0.196和-0.425V。我们确定第一次电子转移依赖于pH，并且质子转移伴随着这一单电子转移。还确定在pH 6.0至8.5范围内第二次电子转移不依赖于pH。
