Protocatechuate 3,4-dioxygenase. Resonance Raman studies of the oxygenated intermediate.
Protocatechuate 3,4-dioxygenase. Resonance Raman studies of the oxygenated intermediate.
复制标题
原儿茶酸 3,4-双加氧酶。
DOI：
10.1016/0006-291x(79)90646-6
复制
发表时间：
1979
影响因子：
3.1
通讯作者：
J. Loehr
中科院分区：
文献类型：
--
作者：
W. Keyes;T. Loehr;M. L. Taylor;J. Loehr
研究了铜绿假单胞菌原儿茶酸3,4-双加氧酶与底物和氧反应时的共振拉曼光谱。研究发现，在没有底物的情况下，翻转酶的光谱与静止酶的光谱难以区分，并且在1263和1174 cm−1处具有共振增强的酪氨酸环振动模式。然而，在三元eso2配合物中，酪氨酸的振动模式分别转移到1252和1165 cm−1。在1300 ~ 200 cm−1范围内，用16o2、18O2和16o18o制备的eso2配合物的光谱中没有任何双氧振动的证据。这个共振拉曼研究的结果被解释为表明分子氧在稳定的中间体中只附着在底物上（而不是铁），并且伴随的底物C4的重排引起了与铁配合物相关的酪氨酸残基的几何结构的实质性变化。此外，eso2配合物的光谱（λmax= 520 nm）以酪氨酸→Fe（III）电荷转移为主，很少或不含过氧化物→Fe（III）电荷转移。这些结果推翻了先前在该酶和呼吸蛋白氧氰菊酯之间的光谱特性的先进类比。
Resonance Raman spectra of protocatechuate 3,4-dioxygenase fromPseudomonas aeruginosahave been investigated during the reaction of the enzyme with substrate and oxygen. It is found that the spectrum of the turned-over enzyme is indistinguishable from that of the resting enzyme in the absence of substrate, and is characterized by resonance-enhanced tyrosinate ring vibrational modes at 1263 and 1174 cm−1. In the ternary ESO2complex, however, the tyrosinate vibrational modes are shifted to 1252 and 1165 cm−1, respectively. There is no evidence for any dioxygen vibrations in the spectra of ESO2complexes prepared with16O2,18O2, and16O18O in the region between 1300 and 200 cm−1. The results of this resonance Raman study are interpreted to indicate that molecular oxygen is attached only to the substrate (but not iron) in the stable intermediate, and that the concomitant rearrangement at C4 of the substrate induces a substantial change in geometry of the tyrosine residues associated with the iron complex. Furthermore, the optical spectrum of the ESO2complex (λmax= 520 nm) is dominated by tyrosinate → Fe(III) charge transfer and contains little or no peroxide → Fe(III) charge transfer. These results invalidate the previously advanced analogy in spectral properties between this enzyme and the respiratory protein, oxyhemerythrin.