Process Requirements of Galactose Oxidase Catalyzed Oxidation of Alcohols
Process Requirements of Galactose Oxidase Catalyzed Oxidation of Alcohols
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DOI：
10.1021/acs.oprd.5b00278
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发表时间：
2015-11-01
影响因子：
3.4
通讯作者：
Woodley, John M.
中科院分区：
文献类型：
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作者：
Pedersen, Asbjorn Toftgaard;Birmingham, William R.;Woodley, John M.
生物催化氧化反应由于其上级区域和立体选择性以及低环境影响，在制药和精细化工中具有替代许多化学催化氧化的潜力。半乳糖氧化酶（GOase）是一种很有前途的生物催化剂，可将伯醇和仲醇分别氧化成相应的醛和酮。然而，GOase需要许多添加剂来维持其催化功能，例如用于降解副产物过氧化氢的酶过氧化氢酶以及用于在酶活性位点中的氨基酸自由基丧失时重新激活酶的单电子氧化剂。和铜离子进行了系统的研究，以找到获得完全活性的GOase所需的最低浓度。此外，还发现缓冲液的浓度和类型对GOase的活性至关重要，GOase在磷酸钠缓冲液中的活性明显高于其他研究缓冲液。酶的稳定性和氧需求对于基于氧化酶的工艺的实施至关重要。GOase在25 ℃搅拌下在缓冲液中完全稳定120 h，如果在类似的实验中也对酶溶液充气，则活性甚至增加30%。相对于氧在水中的溶解度，GOase的氧的高K-m（>5 mM）揭示了在以足够高的速率供应氧和确保高程度的酶利用率（即，确保最高可能的特定反应速率）：然而，GOase的良好稳定性和高活性预示着其作为工业生物催化剂的未来应用。
Biocatalytic oxidation reactions have the potential to substitute many Chemically catalyzed, oxidations, in the pharmaceutical and fine chemical industry due to their superior regio- and stereoselectivity and low environmental impact. Galactose oxidase (GOase) has been shown to be a promising biocatalyst for the Oxidation of primary and secondary alcohols to their corresponding aldehydes and ketones, respectively. However, GOase requires a number of additives to sustain its catalytic function, such as the enzyme catalase for degradation of the byproduct hydrogen peroxide as well as single electron oxidants to reactivate the enzyme upon loss of the amino acid radical in its active site In this work, the addition of catalase, single electron oxidants, and Copper ions was investigated systematically in order to find the minimum concentrations required to Obtain a fully active GOase. Furthermore, it was found that the concentration and type of buffer is essential for the activity of GOase, which was significantly more active in sodium phosphate buffer than in other buffers investigated. Enzyme stability and oxygen requirements are of crucial importance for the implementation of oxidase based processes. GOase was shown to he completely stable for 120 h in buffer with stirring at 25 degrees C, and the activity even increased 30% if the enzyme solution was also aerated in a similar experiment. The high K-m for oxygen of GOase (>5 mM) relative to the solubility of oxygen in water reveals a tradeoff between supplying oxygen at a sufficiently high rate and ensuring a high degree of enzyme utilization (i.e., ensuring the highest possible, specific rate of reaction): Nevertheless, the good stability and high activity of GOase bode well for its future application as an industrial biocatalyst.