Pulsed EPR Study of Amino Acid and Tetrahydropterin Binding in a Tyrosine Hydroxylase Nitric Oxide Complex: Evidence for Substrate Rearrangements in the Formation of the Oxygen-Reactive Complex
作者:Matthew D. Krzyaniak、Bekir E. Eser、Holly R. Ellis、Paul F. Fitzpatrick、John McCracken
DOI:10.1021/bi4010914
日期:2013.11.26
tyrosine and cofactor 6-methyltetrahydropterin with respect to the magnetic axes of the FeNO}7 paramagnetic center. Our results show that the addition of tyrosine triggers a conformational change in the enzyme that reduces the distance from the FeNO}7 center to the closest deuteron on 6,7-2H-6-methyltetrahydropterin from >5.9 Å to 4.4 ± 0.2 Å. Conversely, the addition of 6-methyltetrahydropterin to enzyme
酪氨酸羟化酶是在神经系统中发现的一种非血红素铁酶,可催化酪氨酸羟基化形成l -3,4-二羟基苯丙氨酸,这是儿茶酚胺神经递质生物合成的限速步骤。催化需要结合三种底物:酪氨酸、四氢生物蝶呤和分子氧。我们使用一氧化氮作为 O 2替代物,以S = 3 / 2 FeNO} 7形式在催化位点处平衡 Fe(II),适合 EPR 光谱。2然后使用 H 电子自旋回波包络调制来测量特定氘代底物酪氨酸和辅因子 6-甲基四氢蝶呤相对于 FeNO} 7顺磁中心的磁轴的距离和方向。我们的结果表明,加入酪氨酸的触发以减少从FeNO水平}的距离的酶的构象变化7中心与最接近的氘核上6,7- 2 H-6-methyltetrahydropterin从> 5.9埃至4.4±0.2的. 相反,向用 3,5- 2 H-酪氨酸处理的酶样品添加 6-甲基四氢蝶呤导致S = 3 / 2 , FeNO} 7的磁轴重新定向以氘代底物