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Affiliation(s)
- Kazuo Kobayashi
- The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
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2
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Leung MHM, Mohan P, Pukala TL, Scanlon DB, Lincoln SF, Kee TW. Reduction of Copper(II) to Copper(I) in the Copper-Curcumin Complex Induces Decomposition of Curcumin. Aust J Chem 2012. [DOI: 10.1071/ch12081] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We report the decomposition of curcumin due to reduction of Cu(ii) to Cu(i). Cu(ii) binds tightly with curcumin to form a complex which exhibits a high stability in methanol, but it decomposes readily in acetonitrile and in SDS micelles in the presence of ascorbic acid, coincident with reduction of Cu(ii) to Cu(i). In this study, the UV-Vis absorption of the Cu-curcumin complex shows a monotonic decrease as a function of time, consistent with the decomposition of curcumin. At a high copper : curcumin molar ratio of 10 : 1, the UV-Vis absorption spectrum of the Cu(ii)-curcumin complex in acetonitrile exhibits a substantial blue shift of the absorption maximum from 420 nm to 350 nm, which is indicative of a significant decrease in conjugation length of curcumin in the presence of Cu(ii). Time-dependent mass spectrometry and high performance liquid chromatography (HPLC) data are also consistent with the decomposition of curcumin as a consequence of reduction of Cu(ii) to Cu(i).
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3
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Atochina-Vasserman EN, Gow AJ, Abramova H, Guo CJ, Tomer Y, Preston AM, Beck JM, Beers MF. Immune reconstitution during Pneumocystis lung infection: disruption of surfactant component expression and function by S-nitrosylation. THE JOURNAL OF IMMUNOLOGY 2009; 182:2277-87. [PMID: 19201882 DOI: 10.4049/jimmunol.0802775] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Pneumocystis pneumonia (PCP), the most common opportunistic pulmonary infection associated with HIV infection, is marked by impaired gas exchange and significant hypoxemia. Immune reconstitution disease (IRD) represents a syndrome of paradoxical respiratory failure in patients with active or recently treated PCP subjected to immune reconstitution. To model IRD, C57BL/6 mice were selectively depleted of CD4(+) T cells using mAb GK1.5. Following inoculation with Pneumocystis murina cysts, infection was allowed to progress for 2 wk, GK1.5 was withdrawn, and mice were followed for another 2 or 4 wk. Flow cytometry of spleen cells demonstrated recovery of CD4(+) cells to >65% of nondepleted controls. Lung tissue and bronchoalveolar lavage fluid harvested from IRD mice were analyzed in tandem with samples from CD4-depleted mice that manifested progressive PCP for 6 wks. Despite significantly decreased pathogen burdens, IRD mice had persistent parenchymal lung inflammation, increased bronchoalveolar lavage fluid cellularity, markedly impaired surfactant biophysical function, and decreased amounts of surfactant phospholipid and surfactant protein (SP)-B. Paradoxically, IRD mice also had substantial increases in the lung collectin SP-D, including significant amounts of an S-nitrosylated form. By native PAGE, formation of S-nitrosylated SP-D in vivo resulted in disruption of SP-D multimers. Bronchoalveolar lavage fluid from IRD mice selectively enhanced macrophage chemotaxis in vitro, an effect that was blocked by ascorbate treatment. We conclude that while PCP impairs pulmonary function and produces abnormalities in surfactant components and biophysics, these responses are exacerbated by IRD. This worsening of pulmonary inflammation, in response to persistent Pneumocystis Ags, is mediated by recruitment of effector cells modulated by S-nitrosylated SP-D.
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Affiliation(s)
- Elena N Atochina-Vasserman
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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Scheers NM, Sandberg AS. Ascorbic acid uptake affects ferritin, Dcytb and Nramp2 expression in Caco-2 cells. Eur J Nutr 2008; 47:401-8. [DOI: 10.1007/s00394-008-0741-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Accepted: 09/11/2008] [Indexed: 11/29/2022]
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Kamensky Y, Liu W, Tsai AL, Kulmacz RJ, Palmer G. Axial ligation and stoichiometry of heme centers in adrenal cytochrome b561. Biochemistry 2007; 46:8647-58. [PMID: 17602662 PMCID: PMC2551744 DOI: 10.1021/bi700054g] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Cytochrome (cyt) b561 transports electrons across the membrane of chromaffin granules (CG) present in the adrenal medulla, supporting the biosynthesis of norepinephrine in the CG matrix. We have conducted a detailed characterization of cyt b561 using electron paramagnetic resonance (EPR) and optical spectroscopy on the wild-type and mutant forms of the cytochrome expressed in insect cells. The gz = 3.7 (low-potential heme) and gz = 3.1 (high-potential heme) signals were found to represent the only two authentic hemes of cyt b561; models that propose smaller or greater amounts of heme can be ruled out. We identified the axial ligands to hemes in cyt b561 by mutating four conserved histidines (His54 and His122 at the matrix-side heme center and His88 and His161 at the cytoplasmic-side heme center), thus confirming earlier structural models. Single mutations of any of these histidines produced a constellation of spectroscopic changes that involve not one but both heme centers. We hypothesize that the two hemes and their axial ligands in cyt b561 are integral parts of a structural unit that we term the "kernel". Histidine to glutamine substitutions in the cytoplasmic-side heme center but not in the matrix-side heme center led to the retention of a small fraction of the low-potential heme with gz = 3.7. We provisionally assign the low-potential heme to the matrix side of the membrane; this arrangement suggests that the membrane potential modulates electron transport across the CG membrane.
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Affiliation(s)
- Yury Kamensky
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77251, USA.
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Samms WC, Perera RP, Wimalasena DS, Wimalasena K. Perturbation of dopamine metabolism by 3-amino-2-(4'-halophenyl)propenes leads to increased oxidative stress and apoptotic SH-SY5Y cell death. Mol Pharmacol 2007; 72:744-52. [PMID: 17576792 DOI: 10.1124/mol.107.035873] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have recently characterized a series of 3-amino-2-phenyl-propene (APP) derivatives as reversible inhibitors for the bovine adrenal chromaffin granule vesicular monoamine transporter (VMAT) that have been previously characterized as potent irreversible dopamine-beta-monooxygenase (DbetaM) and monoamine oxidase (MAO) inhibitors. Halogen substitution on the 4'-position of the aromatic ring gradually increases VMAT inhibition potency from 4'-F to 4'-I, parallel to the hydrophobicity of the halogen. We show that these derivatives are taken up into both neuronal and non-neuronal cells, and into resealed chromaffin granule ghosts efficiently through passive diffusion. Uptake rates increased according to the hydrophobicity of the 4'-substituent. More importantly, these derivatives are highly toxic to human neuroblastoma SH-SY5Y but not toxic to M-1, Hep G2, or human embryonic kidney 293 non-neuronal cells at similar concentrations. They drastically perturb dopamine (DA) uptake and metabolism in SH-SY5Y cells under sublethal conditions and are able to deplete both vesicular and cytosolic catecholamines in a manner similar to that of amphetamines. In addition, 4'-IAPP treatment significantly increases intracellular reactive oxygen species (ROS) and decreases glutathione (GSH) levels in SH-SY5Y cells, and cell death is significantly attenuated by the common antioxidants alpha-tocopherol, N-acetyl-l-cysteine and GSH, but not by the nonspecific caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone. DNA fragmentation analysis further supports that cell death is probably due to a caspase-independent ROS-mediated apoptotic pathway. Based on these and other findings, we propose that drastic perturbation of DA metabolism in SH-SY5Y cells by 4'-halo APP derivatives causes increased oxidative stress, leading to apoptotic cell death.
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Affiliation(s)
- Warren C Samms
- Department of Chemistry, Wichita State University, Wichita, Kansas, USA
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7
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Bérczi A, Su D, Lakshminarasimhan M, Vargas A, Asard H. Heterologous expression and site-directed mutagenesis of an ascorbate-reducible cytochrome b561. Arch Biochem Biophys 2005; 443:82-92. [PMID: 16256064 DOI: 10.1016/j.abb.2005.09.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2005] [Revised: 09/09/2005] [Accepted: 09/13/2005] [Indexed: 11/29/2022]
Abstract
Cytochromes b561 (Cyts b561) are ubiquitous membrane proteins catalyzing ascorbate-mediated trans-membrane electron transfer. A heterologous expression system in Saccharomyces cerevisiae was developed to study their structure-function relationship. Recombinant mouse chromaffin granule Cyt b561 (CGCytb) shows spectral characteristics, ascorbate reducibility, and redox potentials identical to that of the native bovine protein. Moreover, the reconstituted recombinant protein mediated trans-membrane electron transport with kinetic characteristics similar to that of bovine CGCytb. Site-directed mutant analysis supports the presence of two hemes coordinated by the highly conserved His pairs H52/H120 and H86/H159. Reduction of CGCytb by ascorbate showed biphasic kinetics (Kd1: 0.016 +/- 0.005 mM, Kd2: 1.24 +/- 0.19 mM). Mutation of a well-conserved Arg residue (R72) abolished high affinity CGCytb reduction by ascorbate, indicating that this residue may be critical for substrate binding. On the other hand, mutation of a Lys previously suggested to play a role in ascorbate binding (K83), did not affect the ascorbate-mediated reduction of the protein.
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Affiliation(s)
- Alajos Bérczi
- Institute of Biophysics, Biological Research Center, Hungarian Academy of Sciences, Szeged, H6701, Hungary
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Nanasato Y, Akashi K, Yokota A. Co-expression of cytochrome b561 and ascorbate oxidase in leaves of wild watermelon under drought and high light conditions. PLANT & CELL PHYSIOLOGY 2005; 46:1515-24. [PMID: 16020428 DOI: 10.1093/pcp/pci164] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Despite carrying out C3 photosynthesis, wild watermelon (Citrullus lanatus sp.) exhibits exceedingly good tolerance to severe drought at high light intensities. However, the mechanism(s) by which this plant protects itself from photodamage has yet to be elucidated. In this study, we characterized wild watermelon cytochrome b561 (cyt b561), which potentially mediates regeneration of apoplastic ascorbate by transferring electrons from cytosolic ascorbate across the plasma membrane. Two cDNA species for wild watermelon cyt b561, designated CLb561A and CLb561B, were isolated. Levels of both CLb561A mRNA and protein were significantly elevated in the leaves during drought at a light intensity of 700 micromol photons m(-2) s(-1). The transcript of CLb561B was detected to a much lesser extent, but no CLb561B protein was produced under any condition used in this study. A transient expression assay with the CLb561A::green fluorescent protein fusion construct showed clear fluorescence on the plasma membrane of onion epidermal cells. The CLb561A protein was enriched in the plasma membrane fraction in leaves of transgenic tobacco expressing CLb561A. Moreover, the high activity of apoplastic ascorbate oxidase (AO), which was able to dispose of cyt b561-transferred reducing equivalents, increased in leaves of wild watermelon grown at high light intensity, but not lower light intensities. Taken together, these observations suggest the occurrence of a novel pathway for excess light energy dissipation in wild watermelon leaves, where excessive energy absorbed by chloroplasts can be transported to and dissipated safely in the apoplasts through the cooperative action of cyt b561 and AO.
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Affiliation(s)
- Yoshihiko Nanasato
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192 Japan
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Asada A, Orii H, Watanabe K, Tsubaki M. Planarian peptidylglycine-hydroxylating monooxygenase, a neuropeptide processing enzyme, colocalizes with cytochrome b561along the central nervous system. FEBS J 2005; 272:942-55. [PMID: 15691328 DOI: 10.1111/j.1742-4658.2004.04528.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Planarians are one of the simplest animal groups with a central nervous system. Their primitive central nervous system produces large quantities of a variety of neuropeptides, of which many are amidated at their C terminus. In vertebrates, peptide amidation is catalyzed by two enzymes [peptidylglycine alpha-hydroxylating monooxygenase (PHM) and peptidyl-alpha-hydroxylglycine alpha-amidating lyase] acting sequentially. In mammals, both enzymatic activities are contained within a single protein that is encoded by a single gene. By utilizing PCR with degenerate oligonucleotides derived from conserved regions of PHM, we succeeded in cloning a full-length cDNA encoding planarian PHM. The deduced amino acid sequence showed full conservation of five His residues and one Met residue, which bind two Cu atoms that are essential for the activity of PHM. Northern blot analysis confirmed the expression of a PHM mRNA of the expected size. Distribution of the mRNA was analyzed by in situ hybridization, showing specific expression in neurons with two morphologically distinct structures, a pair of the ventral nerve cords and the brain. The distribution of PHM was very similar to that of cytochrome b561. This indicates that the ascorbate-related electron transfer system operates in the planarian central nervous system to support the PHM activity and that it predates the emergence of Plathelminthes in the evolutionary history.
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Affiliation(s)
- Akikazu Asada
- Department of Life Science, Graduate School of Life Science, University of Hyogo (formerly Himeji Institute of Technology), Hyogo, Japan
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Griesen D, Su D, Bérczi A, Asard H. Localization of an ascorbate-reducible cytochrome b561 in the plant tonoplast. PLANT PHYSIOLOGY 2004; 134:726-34. [PMID: 14730083 PMCID: PMC344548 DOI: 10.1104/pp.103.032359] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2003] [Revised: 09/23/2003] [Accepted: 10/30/2003] [Indexed: 05/20/2023]
Abstract
As a free radical scavenger, and cofactor, ascorbate (ASC) is a key player in the regulation of cellular redox processes. It is involved in responses to biotic and abiotic stresses and in the control of enzyme activities and metabolic reactions. Cytochromes (Cyts) b561 catalyze ASC-driven trans-membrane electron transport and contribute to ASC-mediated redox reactions in subcellular compartments. Putative Cyts b561 have been identified in Arabidopsis (ecotype Columbia) on the basis of sequence similarity to their mammalian counterparts. However, little is known about the function or subcellular localization of this unique class of membrane proteins. We have expressed one of the putative Arabidopsis Cyt b561 genes (CYBASC1) in yeast and we demonstrate that this protein encodes an ASC-reducible b-type Cyt with absorbance characteristics similar to that of other members of this family. Several lines of independent evidence demonstrate that CYBASC1 is localized at the plant tonoplast (TO). Isoform-specific antibodies against CYBASC1 indicate that this protein cosediments with the TO marker on sucrose gradients. Moreover, CYBASC1 is strongly enriched in TO-enriched membrane fractions, and TO fractions contain an ASC-reducible b-type Cyt with alpha-band absorbance maximum near 561 nm. The TO ASC-reducible Cyt has a high specific activity, suggesting that it is a major constituent of this membrane. These results provide evidence for the presence of trans-membrane redox components in this membrane type, and they suggest the coupling of cytoplasmic and vacuolar metabolic reactions through ASC-mediated redox activity.
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Affiliation(s)
- Daniel Griesen
- Department of Biochemistry, University of Nebraska, Lincoln, Nebraska 68588, USA
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Wimalasena DS, Wimalasena K. Kinetic evidence for channeling of dopamine between monoamine transporter and membranous dopamine-beta-monooxygenase in chromaffin granule ghosts. J Biol Chem 2004; 279:15298-304. [PMID: 14732710 DOI: 10.1074/jbc.m313325200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The nature of coupling between the uptake and dopamine-beta-monooxygenase (DbetaM) catalyzed hydroxylation of dopamine (DA) was studied in bovine chromaffin granule ghosts. Initial rate and transient kinetics of DA uptake and conversion were determined under a variety of conditions. The uptake kinetics of DA, norepinephrine (NE), and epinephrine demonstrate that DA is a better substrate than NE and epinephrine under optimal uptake conditions. The transient kinetics of DA accumulation and NE production under both optimal uptake and uptake and conversion conditions were zero-order with no detectable lag or burst periods. The mathematical analyses of the data show that a normal sequential uptake followed by the conversion process could not explain the observed kinetics, under any condition. On the other hand, all experimental data are in agreement with a mechanism in which DA is efficiently channeled from the vesicular monoamine transporter to membranous DbetaM for hydroxylation, prior to the release into the bulk medium of the ghost interior. The slow accumulation of DA under optimal conversion conditions appears to be caused by the slow leakage of DA from the channeling pathway to the ghost interior. Because DbetaM activity in intact granules is equally distributed between soluble and membranous forms of DbetaM, if an efficient channeling mechanism is operative in vivo, soluble DbetaM may not have access to the substrate, making the catalytic activity of soluble DbetaM physiologically insignificant, which is consistent with the increasing experimental evidence that membranous DbetaM may be the physiologically functional form.
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Wanduragala S, Wimalasena DS, Haines DC, Kahol PK, Wimalasena K. pH-induced alteration and oxidative destruction of heme in purified chromaffin granule cytochrome b(561): implications for the oxidative stress in catecholaminergic neurons. Biochemistry 2003; 42:3617-26. [PMID: 12653566 DOI: 10.1021/bi0206661] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The transmembrane hemoprotein, cytochrome b(561) (b(561)), in the neuroendocrine secretory vesicles is shown to shuttle electrons from the cytosolic ascorbate (Asc) to the intravesicular matrix to provide reducing equivalents for the dopamine beta-monooxygenase (DbetaM) reaction. Intravesicular Asc may also play a role in relieving catecholamine-induced oxidative stress in catecholaminergic neurons. In the present study, we have examined the alteration of purified oxidized b(561) (b(561,ox)) under mild alkaline conditions to probe the structural and functional characteristics of the protein, using UV-vis and EPR spectroscopic and kinetic techniques. Our results show that low spin heme in oxidized b(561) (b(561,ox)) readily transforms to an altered high spin form and then slowly to an Asc nonreducible form, in a pH-, temperature-, and time-dependent manner, which can be described by single-exponential rate equations, A(t) = A(o)(1- e (-kt)) and A(t) = A(o)e(-kt), respectively. More than half of the Asc nonreducible altered b(561) could be converted back to the native b(561) by pH adjustment followed by dithionite reduction, suggesting the reversibility of the process. The heme center of the transformed Asc nonreducible protein is completely bleached instantaneously by dithionite in the presence of atmospheric oxygen, which appears to be mediated by molecular oxygen and/or hydrogen peroxide. These results demonstrate that the heme centers of the protein are susceptible to the pH-induced alteration and oxidative destruction, raising some questions regarding the proposed one alkaline labile, two-heme model of b(561) [Tsubaki, M.; Nakayama, M.; Okuyama, E.; Ichikawa, Y. (1997) J. Biol. Chem. 272, 23206-23210]. The pH-induced alteration and the destruction of heme under oxidative conditions may play a significant role in the amplification of oxidative stress in catecholaminergic neurons.
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Affiliation(s)
- Srimevan Wanduragala
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051, USA
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Srivastava M, Pollard HB, Fleming PJ. Mouse cytochrome b561: cDNA cloning and expression in rat brain, mouse embryos, and human glioma cell lines. DNA Cell Biol 1998; 17:771-7. [PMID: 9778036 DOI: 10.1089/dna.1998.17.771] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A cDNA encoding cytochrome b561 has been isolated from a mouse brain cDNA library, which predicts a protein of 250 amino acids with a deduced Mr of 27,770. Northern blot analysis of different mouse and rat tissues revealed one major mRNA of 3300 bp, which is abundantly distributed in a number of neuroendocrine tissues. In addition, cytochrome mRNA levels in rat brain sections showed the highest distribution of cytochrome b561 in the hypothalamus, hippocampus, thalamus, and striatum, with a moderate level in the cerebral cortex, and the lowest levels in the olfactory bulb and cerebellum. Because non-neuronal cells in the central nervous system contained peptidyl alpha-amidating monooxygenase (PAM), to which cytochrome b561 donates its electrons, we used RT-PCR to document the coexpression of cytochrome b561 with PAM and dopamine beta-hydroxylase (DBH) in glioblastoma cells. Cytochrome b561 expression was detectable in the 11-day-old mouse embryo, and the level of its mRNA increased tenfold by 15 and 17 days of gestation.
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Affiliation(s)
- M Srivastava
- Department of Anatomy and Cell Biology, Uniformed Services University of Health Sciences, Bethesda, MD 20814, USA
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14
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Okuyama E, Yamamoto R, Ichikawa Y, Tsubaki M. Structural basis for the electron transfer across the chromaffin vesicle membranes catalyzed by cytochrome b561: analyses of cDNA nucleotide sequences and visible absorption spectra. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1383:269-78. [PMID: 9602148 DOI: 10.1016/s0167-4838(97)00216-1] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We isolated cDNA clones for cytochromes b561 from sheep and porcine adrenal medullae using the RT-PCR technique. Comparison of the deduced amino acid sequences of various species showed that there are two fully-conserved regions in this cytochrome. In addition, one methionyl and six histidyl residues (potential heme ligands) are fully-conserved. Based on a plausible structural model in which a polypeptide spans the vesicle membranes six times and holds two heme B molecules, the first conserved sequence (69ALLVYRVFR77) is located on the extravesicular side of an alpha-helical segment and the second one (120SLHSW124) is located in an intravesicular loop connecting two alpha-helical segments, respectively. Consideration of the relative locations of the fully-conserved sequences, and the methionyl and histidyl residues in the model led to a proposal that the first and second conserved sequences are likely to form the binding sites for extravesicular ascorbic acid and intravesicular semidehydroascorbic acid, respectively. A mild alkaline-treatment of purified bovine cytochrome b561 in oxidized state led to a specific loss of an electron-accepting ability from ascorbic acid for a half of the heme center, suggesting a distinct role for each of the two hemes.
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Affiliation(s)
- E Okuyama
- Department of Biochemistry, Kagawa Medical University, Japan
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Wimalasena K, Dharmasena S, Wimalasena DS, Hughbanks-Wheaton DK. Reduction of dopamine beta-monooxygenase. A unified model for apparent negative cooperativity and fumarate activation. J Biol Chem 1996; 271:26032-43. [PMID: 8824243 DOI: 10.1074/jbc.271.42.26032] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The interactions of reductants with dopamine beta-monooxygenase (DbetaM) were examined using two novel classes of reductants. The steady-state kinetics of the previously characterized DbetaM reductant, N,N-dimethyl-1,4-p-phenylenediamine (DMPD), were parallel to the ascorbic acid-supported reaction with respect to pH dependence and fumarate activation. DMPD also displayed pH and fumarate-dependent apparent negative cooperativity demonstrating that the previously reported cooperative behavior of DbetaM toward the reductant is not unique to ascorbic acid. The 6-OH phenyl and alkylphenyl-substituted ascorbic acid derivatives were more efficient reductants for the enzyme than ascorbic acid. Kinetic studies suggested that these derivatives behave as pseudo bisubstrates with respect to ascorbic acid and the amine substrate. The lack of apparent cooperative behavior with these derivatives suggests that this behavior of DbetaM is not common for all the reductants. Based on these findings and additional kinetic evidence, the proposal that the apparent negative cooperativity in the interaction of ascorbic acid with DbetaM was due to the presence of a distinct allosteric regulatory site has been ruled out. In contrast to previous models, where fumarate was proposed to interact with a distinct anion binding site, the effect of fumarate on the steady-state kinetics of these novel reductants suggests that fumarate and the reductant may interact with the same site of the enzyme. In accordance with these observations and mathematical analysis of the experimental data, a unified model for the apparent negative cooperativity and fumarate activation of DbetaM in which both fumarate and the reductant interact with the same site of all forms of the enzyme with varying affinities under steady-state turnover conditions has been proposed.
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Affiliation(s)
- K Wimalasena
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051, USA
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16
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Wimalasena K, Wimalasena DS. The reduction of membrane-bound dopamine beta-monooxygenase in resealed chromaffin granule ghosts. Is intragranular ascorbic acid a mediator for extragranular reducing equivalents? J Biol Chem 1995; 270:27516-24. [PMID: 7499210 DOI: 10.1074/jbc.270.46.27516] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The role of internal and external reductants in the dopamine beta-monooxygenase (D beta M)-catalyzed conversion of dopamine to norepinephrine has been investigated in resealed chromaffin granule ghosts. The rate of norepinephrine production was not affected by the exclusion of internal ascorbate. The omission of ascorbate from the external medium drastically reduced the norepinephrine production without affecting the net rate of dopamine uptake. In the presence of the external reductant, the internal ascorbate levels were constant throughout the incubation period. The rate of norepinephrine production was not affected when ghosts were resealed to contain the D beta M reduction site inhibitor, imino-D-glucoascorbate. Ghosts incubated with external imino-D-glucoascorbate reduced the norepinephrine production. The weak D beta M reductant, 6-amino-L-ascorbic acid, was found to be a good external reductant for granule ghosts. The outcome of the above experiments was not altered when dopamine was replaced with the reductively inactive D beta M substrate, tyramine. These results and the known topology of membrane-bound D beta M disfavor the direct reduction of the enzyme by the external reductant. Our observations are consistent with the hypothesis that external ascorbate is the sole source of reducing equivalents for D beta M monooxygenation and that internal soluble ascorbate (or dopamine) may not directly reduce or mediate the reduction of membrane-bound D beta M in resealed granule ghosts.
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Affiliation(s)
- K Wimalasena
- Department of Chemistry, Wichita State University, Kansas 67260-0051, USA
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17
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Navas P, Villalba JM, Córdoba F. Ascorbate function at the plasma membrane. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1197:1-13. [PMID: 8155689 DOI: 10.1016/0304-4157(94)90016-7] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Affiliation(s)
- P Navas
- Departamento de Biología Celular, Facultad de Ciencias, Universidad de Córdoba, Spain
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Dhariwal KR, Shirvan MH, Levine M. Role of Mg-ATP in norepinephrine biosynthesis in intact chromaffin granules. J Neurochem 1994; 62:355-60. [PMID: 8263536 DOI: 10.1046/j.1471-4159.1994.62010355.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Dopamine beta-monooxygenase converts dopamine to norepinephrine in intact chromaffin granules using intragranular ascorbic acid as a cosubstrate. Mg-ATP with external ascorbic acid is required for maximal norepinephrine biosynthesis. Mechanisms to explain these requirements were investigated specifically using intact granules. The effect of Mg-ATP was independent of membrane potential (delta psi) because norepinephrine biosynthesis was unchanged whether delta psi was positive or collapsed. Furthermore, the effect of Mg-ATP was independent of absolute intragranular and extragranular pH as well as the pH difference across the chromaffin granule membrane (delta pH). Nevertheless, norepinephrine biosynthesis was inhibited by N-ethylmaleimide, 4-chloro-7-nitrobenzofurazane, and N,N-dicyclohexylcarbodiimide, specific inhibitors of the secretory vesicle ATPase that may directly affect proton pumping. Biosynthesis occurred normally with other ATPase inhibitors that do not inhibit the ATPase in secretory vesicles. The data indicate that the effect of Mg-ATP with ascorbic acid is mediated by the granule membrane ATPase but independent of maintaining delta psi and delta pH. An explanation of these findings is that Mg-ATP, via the granule ATPase, may change the rate at which protons or dopamine are made available to dopamine beta-monooxygenase.
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Affiliation(s)
- K R Dhariwal
- Laboratory of Cell Biology and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
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Njus D, Kelley PM. The secretory-vesicle ascorbate-regenerating system: a chain of concerted H+/e(-)-transfer reactions. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1144:235-48. [PMID: 8399278 DOI: 10.1016/0005-2728(93)90108-r] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- D Njus
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
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Harnadek GJ, Ries EA, Tse DG, Fitz JS, Njus D. Electron transfer in chromaffin-vesicle ghosts containing peroxidase. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1135:280-6. [PMID: 1623014 DOI: 10.1016/0167-4889(92)90232-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In chromaffin vesicles, the enzyme dopamine beta-monooxygenase converts dopamine to norepinephrine. It is believed that reducing equivalents for this reaction are supplied by intravesicular ascorbic acid and that the ascorbate is regenerated by importing electrons from the cytosol with cytochrome b-561 functioning as the transmembrane electron carrier. If this is true, then the ascorbate-regenerating system should be capable of providing reducing equivalents to any ascorbate-requiring enzyme, not just dopamine beta-monooxygenase. This may be tested using chromaffin-vesicle ghosts in which an exogenous enzyme, horseradish peroxidase, has been trapped. If ascorbate and peroxidase are trapped together within chromaffin-vesicle ghosts, cytochrome b-561 in the vesicle membrane is found in the reduced form. Subsequent addition of H2O2 causes the cytochrome to become partially oxidized. H2O2 does not cause this oxidation if either peroxidase or ascorbate are absent. This argues that the cytochrome is oxidized by semidehydroascorbate, the oxidation product of ascorbate, rather than by H2O2 or peroxidase directly. The semidehydroascorbate must be internal because the ascorbate from which it is formed is sequestered and inaccessible to external ascorbate oxidase. This shows that cytochrome b-561 can transfer electrons to semidehydroascorbate within the vesicles and that the semidehydroascorbate may be generated by any enzyme, not just dopamine beta-monooxygenase.
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Affiliation(s)
- G J Harnadek
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
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Dhariwal K, Black C, Levine M. Semidehydroascorbic acid as an intermediate in norepinephrine biosynthesis in chromaffin granules. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)98781-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Huyghe B, Klinman J. Activity of membranous dopamine beta-monooxygenase within chromaffin granule ghosts. Interaction with ascorbate. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)98991-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Stewart L, Klinman J. Cooperativity in the dopamine beta-monooxygenase reaction. Evidence for ascorbate regulation of enzyme activity. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)98990-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Kelley PM, Jalukar V, Njus D. Rate of electron transfer between cytochrome b561 and extravesicular ascorbic acid. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)45386-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Harnadek GJ, Ries EA, Farhat A, Njus D. 5-Methylphenazinium methylsulfate mediates cyclic electron flow and proton gradient dissipation in chromaffin-vesicle membranes. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)44728-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Wimalasena K, Herman HH, May SW. Effects of dopamine β-monooxygenase substrate analogs on ascorbate levels and norepinephrine synthesis in adrenal chromaffin granule ghosts. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(17)31232-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Levine M, Hartzell W, Bdolah A. Ascorbic acid and Mg-ATP co-regulate dopamine beta-monooxygenase activity in intact chromaffin granules. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(19)77641-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Kelley PM, Njus D. A kinetic analysis of electron transport across chromaffin vesicle membranes. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68995-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Herman HH, Wimalasena K, Fowler LC, Beard CA, May SW. Demonstration of the ascorbate dependence of membrane-bound dopamine beta-monooxygenase in adrenal chromaffin granule ghosts. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(19)35404-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Mackin RB, Flacker JM, Mackin JA, Noe BD. Peptidyl-glycine alpha-amidating monooxygenase is present in islet secretory granules of the anglerfish, Lophius americanus. Gen Comp Endocrinol 1987; 67:263-9. [PMID: 3305155 DOI: 10.1016/0016-6480(87)90156-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Anglerfish islet secretory granules have been examined for the presence of an enzyme which could perform C-terminal amidation of glucagon-like peptide II and possibly anglerfish peptide Y. Using [125I]D-Tyr-Val-Gly as substrate, a peptidyl-glycine alpha-amidating monooxygenase (PAM) was detected in islet secretory granule lysates. The enzyme is active between pH 6.0 and 8.5 and exhibits maximal activity near pH 7.0. The islet PAM requires Cu2+, ascorbate, and molecular oxygen for activity. Other divalent metal ions and redox cofactors were tested and found to be inactive in the assay. Even though added Cu2+ and ascorbate are required for detecting islet PAM activity, when these factors were incubated with substrate in the absence of secretory granule lysate, no activity was observed. It was also found that the addition of higher than optimal concentrations of either Cu2+ or ascorbate inhibited amidating activity. The results demonstrate that a PAM is present in secretory granules of anglerfish islet tissue. The characteristics of the islet PAM are similar to those of PAMs identified and characterized in other tissues which produce bioactive C-terminally amidated peptides.
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Diliberto EJ, Menniti FS, Knoth J, Daniels AJ, Kizer JS, Viveros OH. Adrenomedullary chromaffin cells as a model to study the neurobiology of ascorbic acid: from monooxygenation to neuromodulation. Ann N Y Acad Sci 1987; 498:28-53. [PMID: 2887141 DOI: 10.1111/j.1749-6632.1987.tb23749.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Purified cytochrome b561 catalyzes transmembrane electron transfer for dopamine beta-hydroxylase and peptidyl glycine alpha-amidating monooxygenase activities in reconstituted systems. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)47545-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Menniti FS, Knoth J, Peterson DS, Diliberto EJ. The in situ kinetics of dopamine beta-hydroxylase in bovine adrenomedullary chromaffin cells. Intravesicular compartmentation reduces apparent affinity for the cofactor ascorbate. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)47616-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Abstract
The major function of cytochrome b561 is now clear. This transmembrane protein transports electrons across a secretory vesicle bilayer to supply electrons to monooxygenases inside the secretory vesicle. Cytochrome b561 has been localized not only to adrenergic secretory vesicles, where it supplies electrons to dopamine beta-hydroxylase, but also to peptidergic secretory vesicles that contain peptidyl alpha-amidating monooxygenase. Thus, one would expect to find cytochrome b561 in the membranes of all neuroendocrine cells that contain amidated peptide secretory products. In addition, its wide occurrence as an integral membrane protein of secretory vesicles may make it useful for investigation of vesicle biogenesis and turnover. One of the most important potential roles of cytochrome b561 is that it can be used as a model protein to investigate long-range biological electron transport. This cytochrome is a single polypeptide, which can be purified easily and reconstituted into a functional assembly. It also catalyzes an experimentally unambiguous transmembrane transport of electrons. A full molecular characterization of the structure and function of this cytochrome may provide insights into biological electron transfer which would otherwise be difficult or impossible to obtain.
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Peterkofsky B, Tschank G, Luedke C. Iron-dependent uptake of ascorbate into isolated microsomes. Arch Biochem Biophys 1987; 254:282-9. [PMID: 3034160 DOI: 10.1016/0003-9861(87)90104-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A preliminary study (J.M. Mata, R. Assad, and B. Peterkofsky (1981) Arch. Biochem. Biophys. 206, 93-104) suggested that chick embryo limb bone microsomes took up and concentrated [14C]ascorbate in the presence of cofactors for prolyl hydroxylase. In the present study, we found that the apparent Km for ascorbate in the hydroxylation of intracisternal unhydroxylated procollagen by endogenous prolyl hydroxylase was approximately an order of magnitude less than the value obtained when enzyme solubilized from microsomes was used with an exogenous substrate. These results are compatible with a concentrative uptake of ascorbate into microsomes. The uptake of [14C]ascorbate into microsomes was confirmed and it required only iron, in either the ferrous or ferric form, and was time and temperature dependent, proportional to microsome concentration, and substrate saturable at 2-3 mM ascorbate. Iron-dependent ascorbate uptake also was observed with L-929 cell microsomes. [14C]Ascorbate seemed to be taken up without prior oxidation, since only unlabeled ascorbate, and not dehydroascorbate, competed for uptake into limb bone microsomes. A functional requirement for Fe2+ in ascorbate transport was demonstrated using the intracisternal proline hydroxylating system. L-929 cell microsomes were preincubated with ascorbate with or without the metal and then external ascorbate was oxidized to inactive dehydroascorbate using ascorbic acid oxidase, which cannot penetrate the microsomal membrane. Samples which did not receive iron during the preincubation received it, along with other requirements for prolyl hydroxylase, in a final incubation to measure hydroxylation. Significant hydroxylation was obtained only in samples incubated with iron prior to oxidase treatment, consistent with the conclusion that an iron-dependent process was required to translocate ascorbate and protect it from the oxidase.
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Njus D, Kelley PM, Harnadek GJ, Pacquing YV. Mechanism of ascorbic acid regeneration mediated by cytochrome b561. Ann N Y Acad Sci 1987; 493:108-19. [PMID: 3296905 DOI: 10.1111/j.1749-6632.1987.tb27188.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
In summary, ascorbic acid serves as a one-electron donor for dopamine beta-hydroxylase in chromaffin vesicles and probably for peptide amidating monooxygenase in neurohypophyseal secretory vesicles. It appears that the semidehydroascorbate that is produced is reduced by cytochrome b561 to regenerate intravesicular ascorbate. Cytochrome b561, a transmembrane protein, is reduced in turn by an extravesicular electron donor, probably cytosolic ascorbic acid. It will be interesting to see whether other ascorbate-requiring enzymes in other organelles use a similar ascorbate-regenerating system to provide an intravesicular supply of reducing equivalents.
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Abstract
There are many events in the posttranslational processing of bioactive peptides that occur in secretory granules and not to any great extent in other cellular organelles and that do not appear as modifications of the structure of many conventional neurotransmitters. In addition, at least two very important steps are unique to peptide-containing granules: (1) the peptides must begin their trek to the secretory granule in the RER as a larger precursor, rather than being taken up as a finished or nearly finished product into a mature granule; (2) there is at least one crucial sorting step on the way from the RER to the secretory granule that must occur faithfully before the peptide correctly appears in the granule. As for small molecules such as the catecholamines, the posttranslational processing enzymes and any required cofactors must also be put into the granules if the final events of processing are to occur with fidelity. Many of the posttranslational processing enzymes are only beginning to be identified. It is clear from these studies on purified PAM and peptide alpha-amidation as it occurs in cells that correlating test tube studies with the functioning of secretory granules is a worthwhile, if difficult, pursuit. The unique milieu inside the granule is difficult to mimic in a test tube. Transfection of peptide-producing cells with cDNAs encoding precursors with specific alterations in processing sites offers perhaps the best way to interface the studies of secretory granules and the posttranslational processing enzymes that mediate those functions.
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The Secretory Vesicle in Processing and Secretion of Neuropeptides. ACTA ACUST UNITED AC 1987. [DOI: 10.1016/s0070-2161(08)60064-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Menniti FS, Knoth J, Diliberto EJ. Role of ascorbic acid in dopamine beta-hydroxylation. The endogenous enzyme cofactor and putative electron donor for cofactor regeneration. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(19)75974-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Biosca JA, Greene LE, Eisenberg E. Binding of ADP and ATP analogs to cross-linked and non-cross-linked acto X S-1. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(18)67584-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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An ascorbate shuttle drives catecholamine formation by adrenal chromaffin granules. Nutr Rev 1986; 44:248-50. [PMID: 3554025 DOI: 10.1111/j.1753-4887.1986.tb07646.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
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Njus D, Kelley PM, Harnadek GJ. Bioenergetics of secretory vesicles. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 853:237-65. [PMID: 2887202 DOI: 10.1016/0304-4173(87)90003-6] [Citation(s) in RCA: 171] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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