Inhibition of NADP(H) supply by highly active phosphatase-like ceria nanozymes to boost oxidative stress and ferroptosis

Ceria (CeO₂) with phosphatase-like activity is widely recognized as one of the promising nanozymes. In general, shrinkage of the sizes of CeO₂ can generate large active surface areas for dephosphorylation reactions. However, synthesizing CeO₂ with an ultra-small structure while retaining its surface activity and avoiding its aggregation for use in non-redox biological applications has been a continuous challenge. Herein, a phosphatase-mimicking nanozyme CeO₂ with ultra-small, excellent dispersibility, and accessibility, and largely exposed {111} facet was synthesized via a facile one-pot approach. In contrast to previous reports, which focus on enhancing the ·OH-induced cellular damage by peroxidase- or oxidase-like activity of CeO₂, the present work demonstrates the phosphatase-like activity of CeO₂ for boosting ferroptosis by disrupting cellular homeostasis. Cancer cells require high levels of nicotinamide adenine dinucleotide phosphate (NADP(H)) to enhance GSH synthesis and resist to ferroptosis. By virtue of the phosphatase-like activity, the obtained CeO₂ could sustainably dephosphorylate NADP(H) and effectively inhibit the intracellular biosynthesis of GSH. Our results showed that using CeO₂ as a phosphatase-mimicking nanozyme to deplete NADP(H) and its synthetic precursor glucose-6-phosphate (G6P) could attenuate the repair mechanisms under oxidative stress via indirectly inhibiting the supply of intracellular GSH and enhancing the occurrence of ferroptosis. The finding offers new insights into the regulation of ferroptosis by high-efficiency non-redox nanozymes, which could pave the way for the development of phosphatase-mimicking nanozymes.     

The energetics of metabolism in hydrothermal systems: Calculation of the standard molal thermodynamic properties of magnesium-complexed adenosine nucleotides and NAD and NADP at elevated temperatures and pressures

Calculation of the thermodynamic properties of biomolecules at high temperatures and pressures is fundamental to understanding the energetics of metabolism in hydrothermal systems. Perhaps the most direct interaction between hyperthermophilic microbes and their aquatic and mineralogic habitat involves conversion of environmentally available redox potential into biochemically useful energy. Although chemical thermodynamics can be used to quantify this process, little is known about the thermodynamic properties of the biomolecules involved, especially at high temperatures. However, recent advances in theoretical biogeochemistry make it possible to calculate these properties using the limited experimental data available in the literature, together with group additivity and correlation algorithms, reference model compounds and reactions, and the revised-HKF equations of state. This approach permits calculation of the standard molal thermodynamic properties and equations of state parameters for magnesium-complexed adenosine nucleotides, nicotinamide adenine dinucleotides (NADs), and nicotinamide adenine dinucleotide phosphates (NADPs) as a function of pressure and temperature. The thermodynamic properties and revised-HKF equations of state parameters generated in the present study can be used to carry out comprehensive mass transfer and Gibbs energy calculations to quantify the energetics of microbial energy production in hydrothermal systems.     

Emissive Synthetic Cofactors: Enzymatic Interconversions of tzA Analogues of ATP,NAD+, NADH,NADP+, and NADPH

A series of enzymatic transformations, which generate visibly emissive isofunctional cofactors based on an isothiazolo[4,3‐d]pyrimidine analogue of adenosine ( ^tz A ), was developed. Nicotinamide adenylyl transferase condenses nicotinamide mononucleotide and ^tz ATP to yield N^tzAD⁺ , which can be enzymatically phosphorylated by NAD⁺ kinase and ATP or ^tz ATP to the corresponding N^tzADP⁺ . The latter can be engaged in NADP‐specific coupled enzymatic transformations involving conversion to N^tzADPH by glucose‐6‐phosphate dehydrogenase and reoxidation to N^tzADP⁺ by glutathione reductase. The N^tzADP⁺ / N^tzADPH cycle can be monitored in real time by fluorescence spectroscopy.     

超高效液相色谱-质谱联用法同时快速测定细胞中的4种吡啶核苷酸辅酶

建立了超高效液相色谱-质谱联用法同时测定细胞内4种吡啶核苷酸辅酶(烟酰胺腺嘌呤二核苷酸(NAD+)和烟酰胺腺嘌呤二核苷酸磷酸(NADP+)以及它们的还原态(NADH和NADPH))的方法.样品经甲醇低温快速提取后,在新型混合模式Atlantis PREMIER BEH C18 AX色谱柱上分离,10 mmol/L甲酸铵...     

Substrate selectivity of Gluconobacter oxydans for production of 2,5-diketo-D-gluconic acid and synthesis of 2-keto-L-gulonic acid in a multienzyme system

Substrate selectivity of Gluconobacter oxydans (ATCC 9937) for 2,5-diketo-d-gluconic acid (2,5-DKG) production was investigated with glucose, gluconic acid, and gluconolactone in different concentrations using a resting-cell system. The results show that gluconic acid was utilized favorably by G. oxydans as substrate to produce 2,5-DKG. The strain was coupled with glucose dehydrogenase (GDH) and 2,5-DKG reductase for synthesis of 2-keto-l-gulonic acid (2-KLG), a direct precursor of l-ascorbic acid, from glucose. NADP and NADPH were regenerated between GDH and 2,5-DKG reductase. The mole yield of 2-KLG of this multienzyme system was 16.8%. There are three advantages for using the resting cells of G. oxydans to connect GDH with 2,5-DKG reductase for production of 2-KLG: gluconate produced by GDH may immediately be transformed into 2,5-DKG so that a series of problems generally caused by the accumulation of gluconate would be avoided; 2,5-DKG is supplied directly and continuously for 2,5-DKG reductase, so it is unnecessary to take special measures to deal with this unstable substrate as it was in Sonoyama’s tandem fermentation process; and NADP(H) was regenerated within the system without any other components or systems.     

Emissive Synthetic Cofactors: Enzymatic Interconversions of tzA Analogues of ATP,NAD+, NADH,NADP+, and NADPH

A series of enzymatic transformations, which generate visibly emissive isofunctional cofactors based on an isothiazolo[4,3‐d]pyrimidine analogue of adenosine ( ^tz A ), was developed. Nicotinamide adenylyl transferase condenses nicotinamide mononucleotide and ^tz ATP to yield N^tzAD⁺ , which can be enzymatically phosphorylated by NAD⁺ kinase and ATP or ^tz ATP to the corresponding N^tzADP⁺ . The latter can be engaged in NADP‐specific coupled enzymatic transformations involving conversion to N^tzADPH by glucose‐6‐phosphate dehydrogenase and reoxidation to N^tzADP⁺ by glutathione reductase. The N^tzADP⁺ / N^tzADPH cycle can be monitored in real time by fluorescence spectroscopy.     

光敏胞质雄性不育小麦NAD激酶和NADP磷酸酶对光周期的反应

研究了光敏感胞质雄性不育小麦及其对照可育系，在不同生育期叶片内ＮＡＤ激酶和ＮＡＤＰ磷酸酶的活性对不同光周期的反应．ＬＤ下可育核供体小麦叶片内的ＮＡＤ激酶总活性、ＣａＭ依赖性和ＣａＭ非依赖性ＮＡＤ激酶活性均略高于ＳＤ，但差别不显著；ＮＡＤＰ磷酸酶活性在孕穗、抽穗和籽粒灌浆期均高出ＳＤ一倍以上．光敏胞质雄性不育小麦在ＬＤ和ＳＤ下，叶片中的ＮＡＤ激酶总活性、ＣａＭ依赖性和ＣａＭ非依赖性ＮＡＤ激酶活性以及ＮＡＤＰ磷酸酶活性均有明显差别，而且ＬＤ下ＣａＭ依赖性ＮＡＤ激酶活性逐渐被ＣａＭ非依赖性ＮＡＤ激酶活性所取代．这反应出光敏胞质雄性不育小麦体内的ＮＡＤ激酶和ＮＡＤＰ磷酸酶活性比核供体正常可育系对光周期的反应更敏感，这可能是ＬＤ导致光敏小麦育性转换和花粉败育的原因之一．     

伴有辅酶再生的生物催化过程

很多生物催化的氧化还原反应需要昂贵辅酶的参与,本文详细介绍了伴有辅酶再生的生物催化过程中,辅酶的使用、辅酶的酶反应再生、电化学再生及载体再生的特点,并对各种再生方法的优缺点进行了比较,同时介绍了辅酶的固定化及化学改性方法的研究进展.简单综述了伴有辅酶再生的基于细胞、游离酶和固定化酶的生物催化系统的研究和应用,并展望了辅酶的研究前景及辅酶再生研究的发展方向和亟待解决的问题.     

Hydrogen Evolution from Glucose with the Combination of Glucose Dehydrogenase, Ferredoxin NADP Reductase and Hydrogenase from A. Eutrophus H16

Hydrogen evolution system from glucose consisting of glucose dehydrogenase from Bacillus sp., ferredoxin NADP reductase from spinach leaves and hydrogenase from Alcaligenes eutrophus H16 was established. When the solution containing glucose, glucose dehydrogenase, NAD, ferredoxin NADP reductase, methyl viologen and hydrogenase was incubated at 30°C, hydrogen evolution was observed.