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Liver and Lung Microsomal Metabolism of the Tobacco Alkaloid β-Nicotyrine
Shigenaga, M. K.,Kim, B. H.,Caldera-Munoz, P.,Cairns, T.,Jacob III, P.,Trevor, A. J.,Castagnoli, N. 충남대학교 약학대학 의약품개발연구소 1989 藥學論文集 Vol.5 No.-
The in vitro metabolic fate of β-nicotyrine has been examined in rabbit lung and liver microsomal preparations as part of an effort to characterize the formation of potentially reactive metabolic species that may contribute to the toxic properties of tobacco products. HPLC analysis revealed the formation of an unstable metabolite which displayed HPLC-MS/MS characteristics consistent with the structure 1-methyl-5-(3-pyridyl)-3-pyrrolin-2-one. Attempted synthesis of this pyrrolinone, however, resulted in the isolation of the isomeric 1-methyl-5-(3-pyridyl)-2-pyrrolin-2-one. The HPLC, diode array UV, and mass spectral characteristics of this Δ^4,5-isomer proved to be identical with those of the metabolite derived from β-nicotyrine. Studies in D_2O suggest that the 2- and 3-pyrrolinones are in equilibrium in aqueous solution. The metabolite undergoes autoxidation, possible via radical intermediates, to yield 1-methyl-5-(3-pyridyl)-5-hydroxy-3-pyrrolin-2-one.
Metabolism-Dependent Covalent Binding of S(-)-^3H-Nicotine to Lung Microsomes in Vitro
Kim, Bong Hee,Shigenaga, Mark K. 충남대학교 약학대학 의약품개발연구소 1993 藥學論文集 Vol.9 No.-
Incubation of S(-)-^3H-nicotine with rabbit lung microsomes in the presence of dioxygen and NADPH results in the formation of metabolites that bind covalently to microsomal macromolecules. The addition of cytochrome P-450 monooxygenase inhibitiors, α-methylbenzyl aminobenzotriazole and aroclor 1260, inhibited both (S)-nicotine metabolism and covalent binding. The relative rates of oxidation of nicotine Δ^1',5' iminium ion to cotinine indicates that lung 100,000×g supematant catalyzed this oxidation approximately 18 times slower than that of liver system based on mg of protein, and increased convalent interactions. Since the activity of lung iminium oxidase appears much lower than the liver, it is tempting to speculate that localized concentrations of nicotine Δ^(1',5') iminum ion in the lung will survive for a longer period of time. These results support that cytochrome P-450 catalyzed oxidation of nicotine leads to the formation of reactive and electrophilic intermediates capable of chemical interactions with biomacromolecules.
김봉희,Mark K. Shigenaga 한국환경성돌연변이발암원학회 1989 한국환경성돌연변이·발암원학회지 Vol.9 No.2
Studies on the biodisposition of beta-nicotyrine by lung and liver microsomes was examined in order to provide a better understanding of its fate in this tissue. beta-nicotyrine (100$\mu$M) was incubated with microsomes (1 mg/ml) prepared from New Zealand White rabbits. The rate of oxidation observed in lung microsomal incubations was 1.7 nmoles $\beta$-nicotyrine oxidized mg$^{-1}$ min$^{-1}$ compared with 2.7 nmoles $\beta$-nicotyrine oxidized mg$^{-1}$ min$^{-1}$ by the liver microsomal preparation. However, when these rates were expressed as a function of cytochrome P-450 content, the specific activity of the metabolic oxidation catalyzed by lung (8.3 nmoles $\beta$-nicotyrine oxidized nmole cytochrome P-450$^{-1}$ min$^{-1}$) was approxiamtely 4 times greater than liver microsomes (2.3 nmoles $\beta$-nicotyrine oxidized nmole cytochrome P-450$^{-1}$ min$^{-1}$). Isozyme studies on the oxidation of $\beta$-nicotyrine employed several methods of altering activities of specific isozymes present in pulmonary microsomes, including the use of the isozyme 2 and 6 specific inhibitor $\alpa$-methyl ABT, metabolic inhibitor(MI) complex formation. The results of this inhibition study would appear to indicate the $\beta$-nicotyrine is metabolized predominantly by pulmonary isozyme 5.
Photo-triggered fluorescent labelling of recombinant proteins in live cells
Jung, Deokho,Sato, Kohei,Min, Kyoungmi,Shigenaga, Akira,Jung, Juyeon,Otaka, Akira,Kwon, Youngeun The Royal Society of Chemistry 2015 Chemical communications Vol.51 No.47
<P>A method to photo-chemically trigger fluorescent labelling of proteins in live cells is developed. The approach is based on photo-caged split-intein mediated conditional protein trans-splicing reaction and enabled background-free fluorescent labelling of target proteins with the necessary spatiotemporal control.</P> <P>Graphic Abstract</P><P>A method to photo-chemically trigger fluorescent labelling of proteins in live cells is developed for background-free fluorescent labelling of target proteins with the necessary spatiotemporal control. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5cc01067e'> </P>