Glyoxal oxidase (GLOX) is an extracellular source of H₂O₂ in white-rot secretomes, where it acts in concert with peroxidases to degrade lignin. It has been reported that GLOX requires activation prior to catalytic turnover and that a peroxidase system can fulfill this task. In this study, we verify that an oxidation product of horseradish peroxidase, the radical cation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), is an activator for GLOX. A spectroelectrochemical cell was used to generate the activating radical species, to continuously measure its concentration, and to simultaneously measure the catalytic activity of GLOX based on its O₂ consumption. The results show that GLOX can undergo multiple catalytic turnovers upon activation and that activity increases with the activator concentration. However, we also found that the ABTS cation radical can serve as an electron acceptor which becomes visible in the absence of O₂. Furthermore, GLOX activity is highly restrained by the naturally occurring, low O₂ concentration. We conclude that GLOX is indeed an auxiliary enzyme for H₂O₂ production in white-rot secretomes. Its turnover rate is strongly regulated by the availability of O₂ and the radical generating activity of peroxidases present in the secretome, which acts as a feedback loop for GLOX activity.

乙二醛氧化酶 (GLOX) 是白腐分泌物中 H ₂ O ₂的细胞外来源，它与过氧化物酶协同作用以降解木质素。据报道，GLOX 在催化转化之前需要活化，而过氧化物酶系统可以完成这项任务。在这项研究中，我们验证了辣根过氧化物酶的氧化产物，即 2,2'-叠氮基-双（3-乙基苯并噻唑啉-6-磺酸）的自由基阳离子，是 GLOX 的活化剂。使用光谱电化学电池产生活化自由基物种，连续测量其浓度，同时基于其 O ₂测量 GLOX 的催化活性消耗。结果表明，GLOX 在活化后可以进行多次催化转换，并且活性随着活化剂浓度的增加而增加。然而，我们还发现 ABTS 阳离子自由基可以作为电子受体，在没有 O ₂的情况下变得可见。此外，GLOX 活性受到天然存在的低 O ₂浓度的高度限制。我们得出结论，GLOX 确实是白腐菌分泌组中产生H ₂ O ₂的辅助酶。其周转率受到 O ₂的可用性和分泌组中存在的过氧化物酶的自由基生成活性的强烈调节，分泌组充当 GLOX 活性的反馈回路。