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The Modification of Arginine
Published in Roger L. Lundblad, Claudia M. Noyes, Chemical Reagents for Protein Modification, 1984
Roger L. Lundblad, Claudia M. Noyes
The determination of the extent of arginine modification is generally determined by amino acid analysis after acid hydrolysis but conditions generally need to be modified to prevent loss of the arginine derivative.8 This will be discussed for each of the reagents discussed below. The Sakaguchi reaction16 continues to be useful with recent modifications17,18 and has recently been used, after acid hydrolysis, to determine the extent of arginine modification by 2,3-butanedione.19 The use of ninhydrin as a fluorometric reagent for arginine has been described above.10 Another fluorometric method for the determination of arginine using 9,10-phenanthrenequinone20 has been described. Figure 5 shows the excitation spectrum for the reaction product of arginine and phenanthrenequinone, while the emission spectrum is shown in Figure 6. The structure of 9,10-phenanthrenequinone is shown in Figure 7 as is the likely reaction with arginine. The time course for the reaction with free arginine is shown in Figure 8 while the time course for the reaction with arginyl residues in proteins is shown in Figure 9. This method is some 1000-fold more sensitive than the Sakaguchi reaction but some concern remains concerning the absolute accuracy of the reagent for determination of arginine in peptide linkage. This is also true of the other reagents.
The Modification of Arginine
Published in Roger L. Lundblad, Claudia M. Noyes, Chemical Reagents for Protein Modification, 1984
Roger L. Lundblad, Claudia M. Noyes
The determination of the extent of arginine modification is generally determined by amino acid analysis after acid hydrolysis but conditions generally need to be modified to prevent loss of the arginine derivative.8 This will be discussed for each of the reagents discussed below. The Sakaguchi reaction16 continues to be useful with recent modifications17, 18 and has recently been used, after acid hydrolysis, to determine the extent of arginine modification by 2,3-butanedione.19 The use of ninhydrin as a fluorometric reagent for arginine has been described above.10 Another fluorometric method for the determination of arginine using 9,10-phenanthrenequinone20 has been described. Figure 5 shows the excitation spectrum for the reaction product of arginine and phenanthrenequinone, while the emission spectrum is shown in Figure 6. The structure of 9,10-phenanthrenequinone is shown in Figure 7 as is the likely reaction with arginine. The time course for the reaction with free arginine is shown in Figure 8 while the time course for the reaction with arginyl residues in proteins is shown in Figure 9. This method is some 1000-fold more sensitive than the Sakaguchi reaction but some concern remains concerning the absolute accuracy of the reagent for determination of arginine in peptide linkage. This is also true of the other reagents.
Combination of puerarin and tanshinone IIA alleviates ischaemic stroke injury in rats via activating the Nrf2/ARE signalling pathway
Published in Pharmaceutical Biology, 2022
Qing Miao, Ruihai Wang, Xiaoxin Sun, Song Du, Limei Liu
Puerarin (Pue) and tanshinone IIA (Tan IIA) (Figure 1) are the main active components of Pueraria lobata (Willd.) Ohwi (Leguminosae) and Salvia miltiorrhiza Bge. (Lamiaceae), respectively. They are the most used herbal drugs in China. The combination of the two is recorded in ‘Shijinmo Duiyao’ as a common herb pair for promoting blood circulation and removing blood stasis in the clinical treatment of IS (Lv 2016; Gao et al. 2019; Sun et al. 2020). Numerous studies have shown that Pue, a polyhydroxy isoflavonoid, can selectively accumulate in the ischaemic tissues of the brain, increase cerebral blood flow and vascular endothelial growth factor expression and inhibit the release and production of inflammatory factors, excitatory amino acid toxicity, and oxidative stress (Cheng et al. 2016; Liu et al. 2016; Xu et al. 2016; Kong et al. 2019). Tan IIA is a lipid-soluble derivative of phenanthrenequinone. Tan IIA has demonstrated antioxidant, anti-inflammatory, antibacterial, anti-apoptotic effects, and it can easily penetrate the blood–brain barrier (Chen et al. 2012; Li et al. 2015; Yang et al. 2016; Cai et al. 2017). Injection forms of Pue and Tan IIA have been developed and used clinically in the treatment of cerebrovascular diseases, respectively (Zheng et al. 2017; Zhang et al. 2020). Current clinical studies have shown that the combination of two treatments is more effective than a single injection for reducing the symptoms in patients with affective disorders after the first acute cerebral infarction, with a lower incidence of adverse reactions (Bai and Lv 2014). However, the exact neuroprotective effects and underlying mechanisms of Pue-Tan IIA on the treatment of IS remain unclear and need to be evaluated in depth.
Moonlighting in drug metabolism
Published in Drug Metabolism Reviews, 2021
Lens QOR catalyzes the NADPH-dependent, one-electron reduction of quinones, including 2,6-dichlorophenolindophenol, 1,2-naphthoquinone, 9,10-phenanthrenequinone, methyl-1,4-benzoquinone, and 5-hydroxy-1,4-benzoquinone along with several 2-alkenals, and 3-alken-2-ones (Rao and Zigler 1991; Rao et al. 1992; Porté et al. 2011). 9,10-Phenanthrenequinone is, however, a far better substrate for NAD(P)H:quinone oxidoreductase (NQO1) than for QOR (Porté et al. 2009).
Protective properties of geniposide against UV-B-induced photooxidative stress in human dermal fibroblasts
Published in Pharmaceutical Biology, 2018
Daehyun Shin, Sihyeong Lee, Yu-Hua Huang, Hye-Won Lim, Yoonjin Lee, Kyounghee Jang, Yongwan Cho, Sang Jun Park, Dae-Duk Kim, Chang-Jin Lim
Nrf2 is known as a redox-sensitive transcription factor which plays an important role in the protective process against UV-B-induced photoaging, originally based upon the fact that UV-B-irradiated nrf2–/– mice exhibit accelerated photoaging symptoms and decreased cutaneous GSH levels (Hirota et al. 2011). As a master regulator of the cellular antioxidant defence against environmental electrophilic insult, Nrf2 has emerged as a crucial determinant of cutaneous damage from solar UV, and the concept of pharmacological activation of Nrf2 has attracted considerable attention as a valuable approach to skin photoprotection (Tao et al. 2013). Nrf2 plays a protective role against UV-induced apoptosis in vitro and acute sunburn reactions in vivo, and prevents photoaging by preserving high levels of antioxidants, such as GSH, in the skin (Kim et al. 2015). In a human skin reconstruct exposed to solar simulated UV radiation, dihydrotanshinone, a phenanthrenequinone-based Nrf2 inducer, was found to cause an enhancement in Nrf2 and γ-glutamylcysteine synthetase levels together with the elevation of total GSH levels, and subsequently attenuate the occurrence of epidermal solar insult-markers, such as cleaved procaspase-3, pyknotic nuclei, eosinophilic cytoplasm and acellular cavities (Tao et al. 2013). Sulforaphane, an isothiocyanate derived from broccoli, induces the endogenous cellular defences regulated by Nrf2, including cytoprotective enzymes and GSH (Benedict et al. 2012). The apocarotenoid bixin, a natural food additive consumed worldwide, was previously shown to protect skin against solar UV-induced damage through the activation of Nrf2 (Tao et al. 2015). Geniposide is capable of up-regulating Nrf2 levels diminished under UV-B irradiation, suggesting that geniposide acts as an Nrf2 activator. Subsequently, geniposide causes enhancements in antioxidant components, which may result from its up-regulation of Nrf2. Currently, geniposide is assumed to have its defensive properties against photooxidative stress via the mediation of Nrf2.