Velthuys B, Kok B
Biochim Biophys Acta. 1978 May 10;502(2):211-21. doi: 10.1016/0005-2728(78)90043-9.
A study was made of the interactions of flash-illuminated chloroplasts with hydrogen peroxide. We conclude: 1. The oxygen precursor system can be reduced beyond the S0 state to an S-1 state, which can be oxidized to S0 by a single flash. 2. In the dark, a two-electron donation by H2O2 takes place which reduces S2 to S0 and S1 to S-1. 3. At the same time, two-electron oxidations by H2O2 re-form, S2 from S0 and S1 from S-1. 4. The catalase-like activity due to this cyclic oxidation and reduction of the S enzyme is higher with the S2 in equilibrium S0 couple than with the S1 in equilibrium S-1 couple. Another process, however, is responsible for most of the O2 evolution from H2O2 in the light. Our evidence indicates that this process: (1) is independent of the S states and insensitive to Tris washing, (2) turns over rapidly in high concentrations of peroxide, (3) yields 1 O2 per electron passing through system II; (4) dismutates two H2O2 molecules, so that there is no net consumption of 'holes'.
对闪光照射的叶绿体与过氧化氢的相互作用进行了一项研究。我们得出以下结论：1. 氧前体系统可以被还原至S0状态之外，达到S-1状态，该状态可通过单次闪光被氧化回S0状态。2. 在黑暗中，过氧化氢进行双电子供体反应，将S2还原为S0，将S1还原为S-1。3. 同时，过氧化氢的双电子氧化反应又将S0重新生成S2，将S-1重新生成S1。4. 由于S酶的这种循环氧化和还原作用，S2处于平衡S0对时的过氧化氢酶样活性高于S1处于平衡S-1对时的活性。然而，另一个过程才是光照下过氧化氢产生大部分氧气的原因。我们的证据表明，这个过程：（1）独立于S状态且对Tris洗涤不敏感，（2）在高浓度过氧化物中周转迅速，（3）每一个通过系统II的电子产生1个氧气分子；（4）使两个过氧化氢分子发生歧化反应，因此“空穴”没有净消耗。
