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  1. Article ; Online: ACAT1/SOAT1 Blockade Suppresses LPS-Mediated Neuroinflammation by Modulating the Fate of Toll-like Receptor 4 in Microglia.

    Li, Haibo / Huynh, Thao N / Duong, Michael Tran / Gow, James G / Chang, Catherine C Y / Chang, Ta Yuan

    International journal of molecular sciences

    2023  Volume 24, Issue 6

    Abstract: Cholesterol is stored as cholesteryl esters by the enzymes acyl-CoA:cholesterol acyltransferases/sterol O:acyltransferases (ACATs/SOATs). ACAT1 blockade (A1B) ameliorates the pro-inflammatory responses of macrophages to lipopolysaccharides (LPS) and ... ...

    Abstract Cholesterol is stored as cholesteryl esters by the enzymes acyl-CoA:cholesterol acyltransferases/sterol O:acyltransferases (ACATs/SOATs). ACAT1 blockade (A1B) ameliorates the pro-inflammatory responses of macrophages to lipopolysaccharides (LPS) and cholesterol loading. However, the mediators involved in transmitting the effects of A1B in immune cells is unknown. Microglial
    MeSH term(s) Animals ; Mice ; Acyltransferases/metabolism ; Cholesterol/metabolism ; Lipopolysaccharides/toxicity ; Lipopolysaccharides/metabolism ; Mice, Knockout ; Microglia/metabolism ; Neuroinflammatory Diseases ; Toll-Like Receptor 4/metabolism
    Chemical Substances Acyltransferases (EC 2.3.-) ; Cholesterol (97C5T2UQ7J) ; Lipopolysaccharides ; Toll-Like Receptor 4 ; Acat1 protein, mouse (EC 2.3.1.9) ; sterol O-acyltransferase 1 (EC 2.3.1.26)
    Language English
    Publishing date 2023-03-15
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2019364-6
    ISSN 1422-0067 ; 1422-0067 ; 1661-6596
    ISSN (online) 1422-0067
    ISSN 1422-0067 ; 1661-6596
    DOI 10.3390/ijms24065616
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Acute ACAT1/SOAT1 Blockade Increases MAM Cholesterol and Strengthens ER-Mitochondria Connectivity.

    Harned, Taylor C / Stan, Radu V / Cao, Ze / Chakrabarti, Rajarshi / Higgs, Henry N / Chang, Catherine C Y / Chang, Ta Yuan

    International journal of molecular sciences

    2023  Volume 24, Issue 6

    Abstract: Cholesterol is a key component of all mammalian cell membranes. Disruptions in cholesterol metabolism have been observed in the context of various diseases, including neurodegenerative disorders such as Alzheimer's disease (AD). The genetic and ... ...

    Abstract Cholesterol is a key component of all mammalian cell membranes. Disruptions in cholesterol metabolism have been observed in the context of various diseases, including neurodegenerative disorders such as Alzheimer's disease (AD). The genetic and pharmacological blockade of acyl-CoA:cholesterol acyltransferase 1/sterol O-acyltransferase 1 (ACAT1/SOAT1), a cholesterol storage enzyme found on the endoplasmic reticulum (ER) and enriched at the mitochondria-associated ER membrane (MAM), has been shown to reduce amyloid pathology and rescue cognitive deficits in mouse models of AD. Additionally, blocking ACAT1/SOAT1 activity stimulates autophagy and lysosomal biogenesis; however, the exact molecular connection between the ACAT1/SOAT1 blockade and these observed benefits remain unknown. Here, using biochemical fractionation techniques, we observe cholesterol accumulation at the MAM which leads to ACAT1/SOAT1 enrichment in this domain. MAM proteomics data suggests that ACAT1/SOAT1 inhibition strengthens the ER-mitochondria connection. Confocal and electron microscopy confirms that ACAT1/SOAT1 inhibition increases the number of ER-mitochondria contact sites and strengthens this connection by shortening the distance between these two organelles. This work demonstrates how directly manipulating local cholesterol levels at the MAM can alter inter-organellar contact sites and suggests that cholesterol buildup at the MAM is the impetus behind the therapeutic benefits of ACAT1/SOAT1 inhibition.
    MeSH term(s) Animals ; Mice ; Alzheimer Disease/metabolism ; Cholesterol/metabolism ; Endoplasmic Reticulum/metabolism ; Mammals/metabolism ; Mitochondria/metabolism ; Sterols/metabolism ; Acetyl-CoA C-Acyltransferase/metabolism ; Sterol O-Acyltransferase/metabolism
    Chemical Substances Cholesterol (97C5T2UQ7J) ; Sterols ; Acetyl-CoA C-Acyltransferase (EC 2.3.1.16) ; Sterol O-Acyltransferase (EC 2.3.1.26)
    Language English
    Publishing date 2023-03-14
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2019364-6
    ISSN 1422-0067 ; 1422-0067 ; 1661-6596
    ISSN (online) 1422-0067
    ISSN 1422-0067 ; 1661-6596
    DOI 10.3390/ijms24065525
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: A simple method to disrupt and restore subunit interaction of acyl-CoA:cholesterol acyltransferase 1.

    Neumann, Bryan / Chang, Catherine C Y / Chang, Ta-Yuan

    MethodsX

    2019  Volume 6, Page(s) 2242–2247

    Abstract: Acyl-CoA:cholestereol acyltransferase 1 (ACAT1) is a two-fold dimer (homotetramer) and has two distinct dimerization domains. One domain is in an alpha-helical rich region near the cytoplasmic N-terminus. The other is proposed to be near the C-terminus ... ...

    Abstract Acyl-CoA:cholestereol acyltransferase 1 (ACAT1) is a two-fold dimer (homotetramer) and has two distinct dimerization domains. One domain is in an alpha-helical rich region near the cytoplasmic N-terminus. The other is proposed to be near the C-terminus where multiple transmembrane domains promote hydrophobic interactions between two ACAT1 subunits. The truncation of the ACAT1 N-terminal dimerization domain, Δ1-65, creates a dimer which is fully enzymatically active. It is currently not known how the C-terminal dimerization domain contributes to ACAT1 enzymatic activity. Here we describe a simple method that dissociates ACAT1 dimers through the addition of the non-ionic detergents Triton X-100 or octyl glucoside which disrupt the C-terminal dimerization domain. We also document the protocols for a method to exchange Triton X-100 with CHAPS to restore C-terminal dimerization of the ACAT1 protein, and an optimized liposomal assay to assess ACAT enzymatic activity. •This method can be applied to dissociate ACAT1 subunits by using Triton X-100 or octyl glucoside.•ACAT1 dimerization can be restored by exchanging Triton X-100 with CHAPS.•The liposomal ACAT activity assay conditions have been optimized.
    Language English
    Publishing date 2019-09-20
    Publishing country Netherlands
    Document type Journal Article
    ISSN 2215-0161
    ISSN 2215-0161
    DOI 10.1016/j.mex.2019.09.021
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Triton X-100 or octyl glucoside inactivates acyl-CoA:cholesterol acyltransferase 1 by dissociating it from a two-fold dimer to a two-fold monomer.

    Neumann, Bryan / Chang, Catherine C Y / Chang, Ta-Yuan

    Archives of biochemistry and biophysics

    2019  Volume 671, Page(s) 103–110

    Abstract: Cholesterol is an important lipid molecule and is needed for all mammalian cells. In various cell types, excess cholesterol is stored as cholesteryl esters; acyl-CoA:cholesterol acyltransferase 1 (ACAT1) plays an essential role in this storage process. ... ...

    Abstract Cholesterol is an important lipid molecule and is needed for all mammalian cells. In various cell types, excess cholesterol is stored as cholesteryl esters; acyl-CoA:cholesterol acyltransferase 1 (ACAT1) plays an essential role in this storage process. ACAT1 is located at the endoplasmic reticulum and has nine transmembrane domains (TMDs). It is a member of the membrane-bound O-acyltransferase (MBOAT) family, in which members contain multiple TMDs and participate in a variety of biological functions. When solubilized in the zwitterionic detergent CHAPS, ACAT1 can be purified to homogeneity with full enzyme activity and behaves as a homotetrameric protein. ACAT1 contains two dimerization motifs. The first motif is located near the N-terminus and is not conserved in MBOATs. Deletion of the N-terminal dimerization domain converts ACAT1 to a dimer with full catalytic activity; therefore, ACAT1 is a two-fold dimer. The second dimerization domain, located near the C-terminus, is conserved in MBOATs; however, it was not known whether the C-terminal dimerization domain is required for enzyme activity. Here we show that treating ACAT1 with non-ionic detergent, Triton X-100 or octyl glucoside, causes the enzyme to become a two-fold monomer without any enzymatic activity. Detergent exchange of Triton X-100 with CHAPS restores ACAT1 to a two-fold dimer but fails to restore its enzymatic activity. These results implicate that ACAT1 requires hydrophobic subunit interactions near the C-terminus in order to remain active as a two-fold dimer. Our results also caution the use of Triton X-100 or octyl glucoside to purify other MBOATs.
    MeSH term(s) Acetyl-CoA C-Acetyltransferase/antagonists & inhibitors ; Acetyl-CoA C-Acetyltransferase/metabolism ; Animals ; CHO Cells ; Cholic Acids/chemistry ; Cricetulus ; Detergents/chemistry ; Enzyme Inhibitors/chemistry ; Glucosides/chemistry ; Goats ; HEK293 Cells ; Humans ; Mice ; Octoxynol/chemistry ; Protein Multimerization/drug effects ; Rabbits
    Chemical Substances Cholic Acids ; Detergents ; Enzyme Inhibitors ; Glucosides ; octyl-beta-D-glucoside (29836-26-8) ; Octoxynol (9002-93-1) ; ACAT1 protein, human (EC 2.3.1.9) ; Acetyl-CoA C-Acetyltransferase (EC 2.3.1.9) ; 3-((3-cholamidopropyl)dimethylammonium)-1-propanesulfonate (QBP25342AG)
    Language English
    Publishing date 2019-06-26
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 523-x
    ISSN 1096-0384 ; 0003-9861
    ISSN (online) 1096-0384
    ISSN 0003-9861
    DOI 10.1016/j.abb.2019.06.006
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Nanodisc scaffold peptide (NSP

    Neumann, Bryan / Chao, Kevin / Chang, Catherine C Y / Chang, Ta-Yuan

    Archives of biochemistry and biophysics

    2020  Volume 691, Page(s) 108518

    Abstract: To conduct biochemical studies in vitro, membrane proteins (MPs) must be solubilized with detergents. While detergents are great tools, they can also inhibit the biological activity and/or perturb oligomerization of individual MPs. Nanodisc scaffold ... ...

    Abstract To conduct biochemical studies in vitro, membrane proteins (MPs) must be solubilized with detergents. While detergents are great tools, they can also inhibit the biological activity and/or perturb oligomerization of individual MPs. Nanodisc scaffold peptide (NSP
    MeSH term(s) Amino Acid Sequence ; Animals ; CHO Cells ; Cholic Acids/chemistry ; Cricetulus ; Detergents/chemistry ; Digitonin/chemistry ; Humans ; Peptides/chemistry ; Protein Domains ; Protein Multimerization ; Sterol O-Acyltransferase/chemistry ; Sterol O-Acyltransferase/metabolism ; Surface-Active Agents/chemistry
    Chemical Substances Cholic Acids ; Detergents ; Peptides ; Surface-Active Agents ; Sterol O-Acyltransferase (EC 2.3.1.26) ; sterol O-acyltransferase 1 (EC 2.3.1.26) ; Digitonin (KOO5CM684H) ; 3-((3-cholamidopropyl)dimethylammonium)-1-propanesulfonate (QBP25342AG)
    Language English
    Publishing date 2020-07-28
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 523-x
    ISSN 1096-0384 ; 0003-9861
    ISSN (online) 1096-0384
    ISSN 0003-9861
    DOI 10.1016/j.abb.2020.108518
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article: Cholesterol, Atherosclerosis, and APOE in Vascular Contributions to Cognitive Impairment and Dementia (VCID): Potential Mechanisms and Therapy.

    Duong, Michael Tran / Nasrallah, Ilya M / Wolk, David A / Chang, Catherine C Y / Chang, Ta-Yuan

    Frontiers in aging neuroscience

    2021  Volume 13, Page(s) 647990

    Abstract: Vascular contributions to cognitive impairment and dementia (VCID) are a common cause of cognitive decline, yet limited therapies exist. This cerebrovascular disease results in ... ...

    Abstract Vascular contributions to cognitive impairment and dementia (VCID) are a common cause of cognitive decline, yet limited therapies exist. This cerebrovascular disease results in neurodegeneration
    Language English
    Publishing date 2021-03-25
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2558898-9
    ISSN 1663-4365
    ISSN 1663-4365
    DOI 10.3389/fnagi.2021.647990
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: Nanodisc scaffold peptide (NSPr) replaces detergent by reconstituting acyl-CoA:cholesterol acyltransferase 1 into peptidiscs

    Neumann, Bryan / Chao, Kevin / Chang, Catherine C.Y / Chang, Ta-Yuan

    Archives of biochemistry and biophysics. 2020 Sept. 30, v. 691

    2020  

    Abstract: To conduct biochemical studies in vitro, membrane proteins (MPs) must be solubilized with detergents. While detergents are great tools, they can also inhibit the biological activity and/or perturb oligomerization of individual MPs. Nanodisc scaffold ... ...

    Abstract To conduct biochemical studies in vitro, membrane proteins (MPs) must be solubilized with detergents. While detergents are great tools, they can also inhibit the biological activity and/or perturb oligomerization of individual MPs. Nanodisc scaffold peptide (NSPᵣ), an amphipathic peptide analog of ApoA1, was recently shown to reconstitute detergent solubilized MPs into peptidiscs in vitro. Acyl-coenzyme A:cholesterol acyltransferase 1 (ACAT1), also known as sterol O-acyltransferase 1 (SOAT1), plays a key role in cellular cholesterol storage in various cell types and is a drug target to treat multiple human diseases. ACAT1 contains nine transmembrane domains (TMDs) and primarily forms a homotetramer in vitro and in intact cells; deletion of the N-terminal dimerization domain produces a homodimer with full retention in catalytic activity. ACAT1 is prone to inactivation by numerous detergents. Here we pursued the use of NSPᵣ to overcome the detergent-induced inactivation of ACAT1 by generating near detergent-free ACAT1 peptidiscs. Based on native-PAGE analysis, we showed that NSPᵣ reconstitutes ACAT1 into soluble peptidiscs, in which ACAT1 exists predominantly in oligomeric states greater than a homotetramer. The formation of these higher-order oligomeric states was independent of the N-terminal dimerization domain, suggesting that the oligomerization is mediated through hydrophobic interactions of multiple ACAT1 subunits. ACAT1 peptidiscs were still susceptible to heat-mediated inactivation, presumably due to the residual detergent (CHAPS) bound to ACAT1. We then conditioned ACAT1 with phosphatidylcholine (PC) to replace CHAPS prior to the formation of ACAT1 peptidiscs. The results showed, when PC was included, ACAT1 was present mainly in higher-order oligomeric states with greater enzymatic activity. With PC present, the enzymatic activity of ACAT1 peptidiscs was protected from heat-mediated inactivation. These results support the use of NSPᵣ to create a near detergent-free solution of ACAT1 in peptidiscs for various in vitro studies. Our current results also raise the possibility that, under certain conditions, ACAT1 may form higher-order oligomeric states in vivo.
    Keywords bioactive properties ; biophysics ; catalytic activity ; cholesterol ; cholesterol acyltransferase ; detergents ; dimerization ; drugs ; enzyme activity ; humans ; hydrophobicity ; oligomerization ; peptides ; phosphatidylcholines ; solubilization ; surfactants
    Language English
    Dates of publication 2020-0930
    Publishing place Elsevier Inc.
    Document type Article
    Note NAL-AP-2-clean
    ZDB-ID 523-x
    ISSN 1096-0384 ; 0003-9861
    ISSN (online) 1096-0384
    ISSN 0003-9861
    DOI 10.1016/j.abb.2020.108518
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  8. Article ; Online: Stealth Liposomes Encapsulating a Potent ACAT1/SOAT1 Inhibitor F12511: Pharmacokinetic, Biodistribution, and Toxicity Studies in Wild-Type Mice and Efficacy Studies in Triple Transgenic Alzheimer's Disease Mice.

    De La Torre, Adrianna L / Huynh, Thao N / Chang, Catherine C Y / Pooler, Darcy B / Ness, Dylan B / Lewis, Lionel D / Pannem, Sanjana / Feng, Yichen / Samkoe, Kimberley S / Hickey, William F / Chang, Ta Yuan

    International journal of molecular sciences

    2023  Volume 24, Issue 13

    Abstract: Cholesterol is essential for cellular function and is stored as cholesteryl esters (CEs). CEs biosynthesis is catalyzed by the enzymes acyl-CoA:cholesterol acyltransferase 1 and 2 (ACAT1 and ACAT2), with ACAT1 being the primary isoenzyme in most cells in ...

    Abstract Cholesterol is essential for cellular function and is stored as cholesteryl esters (CEs). CEs biosynthesis is catalyzed by the enzymes acyl-CoA:cholesterol acyltransferase 1 and 2 (ACAT1 and ACAT2), with ACAT1 being the primary isoenzyme in most cells in humans. In Alzheimer's Disease, CEs accumulate in vulnerable brain regions. Therefore, ACATs may be promising targets for treating AD. F12511 is a high-affinity ACAT1 inhibitor that has passed phase 1 safety tests for antiatherosclerosis. Previously, we developed a nanoparticle system to encapsulate a large concentration of F12511 into a stealth liposome (DSPE-PEG
    MeSH term(s) Humans ; Mice ; Animals ; Mice, Transgenic ; Alzheimer Disease/drug therapy ; Alzheimer Disease/pathology ; Liposomes ; Tissue Distribution ; Tandem Mass Spectrometry ; Acetyl-CoA C-Acetyltransferase/metabolism
    Chemical Substances eflucimibe (3DK1X2C37M) ; Liposomes ; ACAT1 protein, human (EC 2.3.1.9) ; Acetyl-CoA C-Acetyltransferase (EC 2.3.1.9)
    Language English
    Publishing date 2023-07-02
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2019364-6
    ISSN 1422-0067 ; 1422-0067 ; 1661-6596
    ISSN (online) 1422-0067
    ISSN 1422-0067 ; 1661-6596
    DOI 10.3390/ijms241311013
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article: A simple method to disrupt and restore subunit interaction of acyl-CoA:cholesterol acyltransferase 1

    Neumann, Bryan / Chang, Catherine C.Y / Chang, Ta-Yuan

    MethodsX. 2019, v. 6

    2019  

    Abstract: Acyl-CoA:cholestereol acyltransferase 1 (ACAT1) is a two-fold dimer (homotetramer) and has two distinct dimerization domains. One domain is in an alpha-helical rich region near the cytoplasmic N-terminus. The other is proposed to be near the C-terminus ... ...

    Abstract Acyl-CoA:cholestereol acyltransferase 1 (ACAT1) is a two-fold dimer (homotetramer) and has two distinct dimerization domains. One domain is in an alpha-helical rich region near the cytoplasmic N-terminus. The other is proposed to be near the C-terminus where multiple transmembrane domains promote hydrophobic interactions between two ACAT1 subunits. The truncation of the ACAT1 N-terminal dimerization domain, Δ1-65, creates a dimer which is fully enzymatically active. It is currently not known how the C-terminal dimerization domain contributes to ACAT1 enzymatic activity. Here we describe a simple method that dissociates ACAT1 dimers through the addition of the non-ionic detergents Triton X-100 or octyl glucoside which disrupt the C-terminal dimerization domain. We also document the protocols for a method to exchange Triton X-100 with CHAPS to restore C-terminal dimerization of the ACAT1 protein, and an optimized liposomal assay to assess ACAT enzymatic activity.•This method can be applied to dissociate ACAT1 subunits by using Triton X-100 or octyl glucoside.•ACAT1 dimerization can be restored by exchanging Triton X-100 with CHAPS.•The liposomal ACAT activity assay conditions have been optimized.
    Keywords cholesterol acyltransferase ; detergents ; dimerization ; enzyme activity ; glucosides ; hydrophobic bonding ; octoxynol
    Language English
    Size p. 2242-2247.
    Publishing place Elsevier B.V.
    Document type Article
    ISSN 2215-0161
    DOI 10.1016/j.mex.2019.09.021
    Database NAL-Catalogue (AGRICOLA)

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  10. Article: Triton X-100 or octyl glucoside inactivates acyl-CoA:cholesterol acyltransferase 1 by dissociating it from a two-fold dimer to a two-fold monomer

    Neumann, Bryan / Chang, Catherine C.Y / Chang, Ta-Yuan

    Archives of biochemistry and biophysics. 2019 Aug. 15, v. 671

    2019  

    Abstract: Cholesterol is an important lipid molecule and is needed for all mammalian cells. In various cell types, excess cholesterol is stored as cholesteryl esters; acyl-CoA:cholesterol acyltransferase 1 (ACAT1) plays an essential role in this storage process. ... ...

    Abstract Cholesterol is an important lipid molecule and is needed for all mammalian cells. In various cell types, excess cholesterol is stored as cholesteryl esters; acyl-CoA:cholesterol acyltransferase 1 (ACAT1) plays an essential role in this storage process. ACAT1 is located at the endoplasmic reticulum and has nine transmembrane domains (TMDs). It is a member of the membrane-bound O-acyltransferase (MBOAT) family, in which members contain multiple TMDs and participate in a variety of biological functions. When solubilized in the zwitterionic detergent CHAPS, ACAT1 can be purified to homogeneity with full enzyme activity and behaves as a homotetrameric protein. ACAT1 contains two dimerization motifs. The first motif is located near the N-terminus and is not conserved in MBOATs. Deletion of the N-terminal dimerization domain converts ACAT1 to a dimer with full catalytic activity; therefore, ACAT1 is a two-fold dimer. The second dimerization domain, located near the C-terminus, is conserved in MBOATs; however, it was not known whether the C-terminal dimerization domain is required for enzyme activity. Here we show that treating ACAT1 with non-ionic detergent, Triton X-100 or octyl glucoside, causes the enzyme to become a two-fold monomer without any enzymatic activity. Detergent exchange of Triton X-100 with CHAPS restores ACAT1 to a two-fold dimer but fails to restore its enzymatic activity. These results implicate that ACAT1 requires hydrophobic subunit interactions near the C-terminus in order to remain active as a two-fold dimer. Our results also caution the use of Triton X-100 or octyl glucoside to purify other MBOATs.
    Keywords catalytic activity ; cholesterol ; cholesterol acyltransferase ; cholesteryl esters ; detergents ; dimerization ; endoplasmic reticulum ; enzyme activity ; glucosides ; hydrophobicity ; mammals ; octoxynol ; solubilization ; zwitterions
    Language English
    Dates of publication 2019-0815
    Size p. 103-110.
    Publishing place Elsevier Inc.
    Document type Article
    ZDB-ID 523-x
    ISSN 1096-0384 ; 0003-9861
    ISSN (online) 1096-0384
    ISSN 0003-9861
    DOI 10.1016/j.abb.2019.06.006
    Database NAL-Catalogue (AGRICOLA)

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