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Ishikawa E, Kanai S, Shinozawa A, Hyakutake M, Sue M. Hordeum vulgare CYP76M57 catalyzes C 2 shortening of tryptophan side chain by C-N bond rearrangement in gramine biosynthesis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 118:892-904. [PMID: 38281119 DOI: 10.1111/tpj.16644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 12/25/2023] [Accepted: 01/07/2024] [Indexed: 01/29/2024]
Abstract
The indole alkaloid gramine, 3-(dimethylaminomethyl)indole, is a defensive specialized metabolite found in some barley cultivars. In its biosynthetic process, the tryptophan (Trp) side chain is shortened by two carbon atoms to produce 3-(aminomethyl)indole (AMI), which is then methylated by N-methyltransferase (HvNMT) to produce gramine. Although side chain shortening is one of the crucial scaffold formation steps of alkaloids originating from aromatic amino acids, the gene and enzyme involved in the Trp-AMI conversion reactions are unknown. In this study, through RNA-seq analysis, 35 transcripts were shown to correlate with gramine production; among them, an uncharacterized cytochrome P450 (CYP) gene, CYP76M57, and HvNMT were identified as candidate genes for gramine production. Transgenic Arabidopsis thaliana and rice overexpressing CYP and HvNMT accumulate AMI, N-methyl-AMI, and gramine. CYP76M57, heterologously expressed in Pichia pastoris, was able to act on Trp to produce AMI. Furthermore, the amino group nitrogen of Trp was retained during the CYP76M57-catalyzed reaction, indicating that the C2 shortening of Trp proceeds with an unprecedented biosynthetic process, the removal of the carboxyl group and Cα and the rearrangement of the nitrogen atom to Cβ. In some gramine-non-accumulating barley cultivars, arginine 104 in CYP76M57 is replaced by threonine, which abolished the catalytic activity of CYP76M57 to convert Trp into AMI. These results uncovered the missing committed enzyme of gramine biosynthesis in barley and contribute to the elucidation of the potential functions of CYPs in plants and undiscovered specialized pathways.
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Affiliation(s)
- Erika Ishikawa
- Department of Agricultural Chemistry, Tokyo University of Agriculture, Sakuragaoka 1-1-1, Setagaya, Tokyo, 156-8502, Japan
| | - Shion Kanai
- Department of Agricultural Chemistry, Tokyo University of Agriculture, Sakuragaoka 1-1-1, Setagaya, Tokyo, 156-8502, Japan
| | - Akihisa Shinozawa
- Department of Bioscience, Tokyo University of Agriculture, Sakuragaoka 1-1-1, Setagaya, Tokyo, 156-8502, Japan
- The NODAI Genome Research Center (NGRC), Tokyo University of Agriculture, Sakuragaoka 1-1-1, Setagaya, Tokyo, 156-8502, Japan
| | - Mami Hyakutake
- Department of Agricultural Chemistry, Tokyo University of Agriculture, Sakuragaoka 1-1-1, Setagaya, Tokyo, 156-8502, Japan
| | - Masayuki Sue
- Department of Agricultural Chemistry, Tokyo University of Agriculture, Sakuragaoka 1-1-1, Setagaya, Tokyo, 156-8502, Japan
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2
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Jindal G, Kaur N. Fluorescent water-stable quantum dots possessing benzimidazole for the recognition of bisulfate in edible materials, soap, and medicine. J Photochem Photobiol A Chem 2022. [DOI: 10.1016/j.jphotochem.2021.113652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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3
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Annunziata F, Pinna C, Dallavalle S, Tamborini L, Pinto A. An Overview of Coumarin as a Versatile and Readily Accessible Scaffold with Broad-Ranging Biological Activities. Int J Mol Sci 2020; 21:E4618. [PMID: 32610556 PMCID: PMC7370201 DOI: 10.3390/ijms21134618] [Citation(s) in RCA: 131] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 06/22/2020] [Accepted: 06/28/2020] [Indexed: 12/19/2022] Open
Abstract
Privileged structures have been widely used as an effective template for the research and discovery of high value chemicals. Coumarin is a simple scaffold widespread in Nature and it can be found in a considerable number of plants as well as in some fungi and bacteria. In the last years, these natural compounds have been gaining an increasing attention from the scientific community for their wide range of biological activities, mainly due to their ability to interact with diverse enzymes and receptors in living organisms. In addition, coumarin nucleus has proved to be easily synthetized and decorated, giving the possibility of designing new coumarin-based compounds and investigating their potential in the treatment of various diseases. The versatility of coumarin scaffold finds applications not only in medicinal chemistry but also in the agrochemical field as well as in the cosmetic and fragrances industry. This review is intended to be a critical overview on coumarins, comprehensive of natural sources, metabolites, biological evaluations and synthetic approaches.
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Affiliation(s)
- Francesca Annunziata
- Department of Pharmaceutical Science, University of Milan, via Mangiagalli 25, 20133 Milan, Italy; (F.A.); (C.P.)
| | - Cecilia Pinna
- Department of Pharmaceutical Science, University of Milan, via Mangiagalli 25, 20133 Milan, Italy; (F.A.); (C.P.)
| | - Sabrina Dallavalle
- Department of Food, Environmental and Nutritional Sciences, University of Milan, via Celoria 2, 20133 Milan, Italy; (S.D.); (A.P.)
| | - Lucia Tamborini
- Department of Pharmaceutical Science, University of Milan, via Mangiagalli 25, 20133 Milan, Italy; (F.A.); (C.P.)
| | - Andrea Pinto
- Department of Food, Environmental and Nutritional Sciences, University of Milan, via Celoria 2, 20133 Milan, Italy; (S.D.); (A.P.)
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4
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Vargas-Mendoza N, Morales-González Á, Morales-Martínez M, Soriano-Ursúa MA, Delgado-Olivares L, Sandoval-Gallegos EM, Madrigal-Bujaidar E, Álvarez-González I, Madrigal-Santillán E, Morales-Gonzalez JA. Flavolignans from Silymarin as Nrf2 Bioactivators and Their Therapeutic Applications. Biomedicines 2020; 8:biomedicines8050122. [PMID: 32423098 PMCID: PMC7277158 DOI: 10.3390/biomedicines8050122] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/06/2020] [Accepted: 05/06/2020] [Indexed: 02/07/2023] Open
Abstract
Silymarin (SM) is a mixture of flavolignans extracted from the seeds of species derived from Silybum marianum, commonly known as milk thistle or St. Mary'sthistle. These species have been widely used in the treatment of liver disorders in traditional medicine since ancient times. Several properties had been attributed to the major SM flavolignans components, identified as silybin, isosilybin, silychristin, isosilychristin, and silydianin. Previous research reported antioxidant and protective activities, which are probably related to the activation of the nuclear factor erythroid 2 (NFE2)-related factor 2 (Nrf2), known as a master regulator of the cytoprotector response. Nrf2 is a redox-sensitive nuclear transcription factor able to induce the downstream-associated genes. The disruption of Nrf2 signaling has been associated with different pathological conditions. Some identified phytochemicals from SM had shown to participate in the Nrf2 signaling pathway; in particular, they have been suggested as activators that disrupt interactions in the Keap1-Nrf2 system, but also as antioxidants or with additional actions regarding Nrf2 regulation. Thus, the study of these molecules makes them appear attractive as novel targets for the treatment or prevention of several diseases.
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Affiliation(s)
- Nancy Vargas-Mendoza
- Laboratorio de Medicina de Conservación, Escuela Superior de Medicina, Instituto Politécnico Nacional, México Escuela Superior de Medicina, Plan de San Luis y Díaz Mirón, Col. Casco de Santo Tomás, Alcaldía Miguel Hidalgo, Mexico City 11340, Mexico;
| | - Ángel Morales-González
- Escuela Superior de Cómputo, Instituto Politécnico Nacional, Av. Juan de Dios Bátiz s/n esquina Miguel Othón de Mendizabal, Unidad Profesional Adolfo López Mateos, Mexico City CP 07738, Mexico;
| | - Mauricio Morales-Martínez
- Licenciatura en Nutrición, Universidad Intercontinental, Insurgentes Sur 4303, Santa Úrsula Xitla, Alcaldía Tlalpan, Mexico City CP 14420, Mexico;
| | - Marvin A. Soriano-Ursúa
- Academia de Fisiología Humana, Escuela Superior de Medicina, Instituto Politécnico Nacional, Plan de San Luis y Díaz Mirón, Col. Casco de Santo Tomás, Del. Miguel Hidalgo, Mexico City 11340, Mexico;
| | - Luis Delgado-Olivares
- Centro de Investigación Interdisciplinario, Área Académica de Nutrición, Instituto de Ciencias de la Salud. Universidad Autónoma del Estado de Hidalgo. Circuito Actopan-Tilcuauttla, s/n, Ex hacienda La Concepción, San Agustín Tlaxiaca, Hidalgo CP 42160, Mexico; (L.D.-O.); (E.M.S.-G.)
| | - Eli Mireya Sandoval-Gallegos
- Centro de Investigación Interdisciplinario, Área Académica de Nutrición, Instituto de Ciencias de la Salud. Universidad Autónoma del Estado de Hidalgo. Circuito Actopan-Tilcuauttla, s/n, Ex hacienda La Concepción, San Agustín Tlaxiaca, Hidalgo CP 42160, Mexico; (L.D.-O.); (E.M.S.-G.)
| | - Eduardo Madrigal-Bujaidar
- Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, “Unidad Profesional A. López Mateos”. Av. Wilfrido Massieu. Col., Zacatenco, Mexico City 07738, Mexico; (E.M.-B.); (I.Á.-G.)
| | - Isela Álvarez-González
- Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, “Unidad Profesional A. López Mateos”. Av. Wilfrido Massieu. Col., Zacatenco, Mexico City 07738, Mexico; (E.M.-B.); (I.Á.-G.)
| | - Eduardo Madrigal-Santillán
- Laboratorio de Medicina de Conservación, Escuela Superior de Medicina, Instituto Politécnico Nacional, México Escuela Superior de Medicina, Plan de San Luis y Díaz Mirón, Col. Casco de Santo Tomás, Alcaldía Miguel Hidalgo, Mexico City 11340, Mexico;
- Correspondence: (E.M.-S.); (J.A.M.-G.); Tel.: +52-55-5729-6300 (E.M.-S. & J.A.M.-G.)
| | - José A. Morales-Gonzalez
- Laboratorio de Medicina de Conservación, Escuela Superior de Medicina, Instituto Politécnico Nacional, México Escuela Superior de Medicina, Plan de San Luis y Díaz Mirón, Col. Casco de Santo Tomás, Alcaldía Miguel Hidalgo, Mexico City 11340, Mexico;
- Correspondence: (E.M.-S.); (J.A.M.-G.); Tel.: +52-55-5729-6300 (E.M.-S. & J.A.M.-G.)
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5
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Nair RR, Raju M, Bhai S, Raval IH, Haldar S, Ganguly B, Chatterjee PB. Estimation of bisulfate in edible plant foods, dog urine, and drugs: picomolar level detection and bio-imaging in living organisms. Analyst 2020; 144:5724-5737. [PMID: 31486453 DOI: 10.1039/c9an01078e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In order to explore the properties of any species in solution, the actual, i.e. equilibrium concentration of the free species should be taken into account. Researchers have not paid attention to the deprotonation equilibrium between HSO4- and SO42- while probing bisulfate ion. In this study, we have addressed this concern and developed two zwitterions, CG (coumarin-integrated glycine) and CA (coumarin-integrated alanine), for the selective detection of HSO4- at a picomolar level (50 to 325 pM) with very high binding affinity (∼108 M-1) in pure water at physiological pH. The principle of HSO4- recognition was established via UV-vis and fluorescence techniques. DFT calculations suggested that the H-bonding interactions between the probes and HSO4- are the driving force for this unforeseen selectivity. The membrane penetration ability and nontoxicity of CG/CA enable them to function as staining agents in living brine shrimps and bacteria. The use of these probes for the estimation of HSO4- in various day-to-day edible foods and drugs along with urine samples is unprecedented. The significance and novelty of this study lies in the application and development of assays for estimating bisulfate in several real-world samples that are predominantly aqueous in nature, which are the first of their kind.
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Affiliation(s)
- Ratish R Nair
- Analytical and Environmental Science Division and Centralized Instrument Facility, CSIR-CSMCRI, G. B. Marg, Bhavnagar, India.
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6
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Ho CL, Tan HQ, Chua KJ, Kang A, Lim KH, Ling KL, Yew WS, Lee YS, Thiery JP, Chang MW. Engineered commensal microbes for diet-mediated colorectal-cancer chemoprevention. Nat Biomed Eng 2018; 2:27-37. [PMID: 31015663 DOI: 10.1038/s41551-017-0181-y] [Citation(s) in RCA: 148] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 11/27/2017] [Indexed: 01/07/2023]
Abstract
Chemoprevention-the use of medication to prevent cancer-can be augmented by the consumption of produce enriched with natural metabolites. However, chemopreventive metabolites are typically inactive and have low bioavailability and poor host absorption. Here, we show that engineered commensal microbes can prevent carcinogenesis and promote the regression of colorectal cancer through a cruciferous vegetable diet. The engineered commensal Escherichia coli bound specifically to the heparan sulphate proteoglycan on colorectal cancer cells and secreted the enzyme myrosinase to transform host-ingested glucosinolates-natural components of cruciferous vegetables-to sulphoraphane, an organic small molecule with known anticancer activity. The engineered microbes coupled with glucosinolates resulted in >95% proliferation inhibition of murine, human and colorectal adenocarcinoma cell lines in vitro. We also show that murine models of colorectal carcinoma fed with the engineered microbes and the cruciferous vegetable diet displayed significant tumour regression and reduced tumour occurrence.
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Affiliation(s)
- Chun Loong Ho
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Hui Qing Tan
- Department of Gastroenterology and Hepatology, Singapore General Hospital, Singapore, Singapore
| | - Koon Jiew Chua
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Aram Kang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Kiat Hon Lim
- Department of Pathology, Singapore General Hospital, Singapore, Singapore
| | - Khoon Lin Ling
- Department of Gastroenterology and Hepatology, Singapore General Hospital, Singapore, Singapore
| | - Wen Shan Yew
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Yung Seng Lee
- NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), Life Sciences Institute, National University of Singapore, Singapore, Singapore.,Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Jean Paul Thiery
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Matthew Wook Chang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore. .,NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), Life Sciences Institute, National University of Singapore, Singapore, Singapore.
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7
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Unusual active site location and catalytic apparatus in a glycoside hydrolase family. Proc Natl Acad Sci U S A 2017; 114:4936-4941. [PMID: 28396425 DOI: 10.1073/pnas.1701130114] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The human gut microbiota use complex carbohydrates as major nutrients. The requirement for an efficient glycan degrading systems exerts a major selection pressure on this microbial community. Thus, we propose that these bacteria represent a substantial resource for discovering novel carbohydrate active enzymes. To test this hypothesis, we focused on enzymes that hydrolyze rhamnosidic bonds, as cleavage of these linkages is chemically challenging and there is a paucity of information on l-rhamnosidases. Here we screened the activity of enzymes derived from the human gut microbiota bacterium Bacteroides thetaiotaomicron, which are up-regulated in response to rhamnose-containing glycans. We identified an α-l-rhamnosidase, BT3686, which is the founding member of a glycoside hydrolase (GH) family, GH145. In contrast to other rhamnosidases, BT3686 cleaved l-Rha-α1,4-d-GlcA linkages through a retaining double-displacement mechanism. The crystal structure of BT3686 showed that the enzyme displayed a type A seven-bladed β-propeller fold. Mutagenesis and crystallographic studies, including the structure of BT3686 in complex with the reaction product GlcA, revealed a location for the active site among β-propeller enzymes cited on the posterior surface of the rhamnosidase. In contrast to the vast majority of GH, the catalytic apparatus of BT3686 does not comprise a pair of carboxylic acid residues but, uniquely, a single histidine functions as the only discernable catalytic amino acid. Intriguingly, the histidine, His48, is not invariant in GH145; however, when engineered into structural homologs lacking the imidazole residue, α-l-rhamnosidase activity was established. The potential contribution of His48 to the catalytic activity of BT3686 is discussed.
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8
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Klingaman CA, Wagner MJ, Brown JR, Klecker JB, Pauley EH, Noldner CJ, Mays JR. HPLC-based kinetics assay facilitates analysis of systems with multiple reaction products and thermal enzyme denaturation. Anal Biochem 2016; 516:37-47. [PMID: 27742213 DOI: 10.1016/j.ab.2016.10.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 09/20/2016] [Accepted: 10/10/2016] [Indexed: 12/19/2022]
Abstract
Glucosinolates are plant secondary metabolites abundant in Brassica vegetables that are substrates for the enzyme myrosinase, a thioglucoside hydrolase. Enzyme-mediated hydrolysis of glucosinolates forms several organic products, including isothiocyanates (ITCs) that have been explored for their beneficial effects in humans. Myrosinase has been shown to be tolerant of non-natural glucosinolates, such as 2,2-diphenylethyl glucosinolate, and can facilitate their conversion to non-natural ITCs, some of which are leads for drug development. An HPLC-based method capable of analyzing this transformation for non-natural systems has been described. This current study describes (1) the Michaelis-Menten characterization of 2,2-diphenyethyl glucosinolate and (2) a parallel evaluation of this analogue and the natural analogue glucotropaeolin to evaluate effects of pH and temperature on rates of hydrolysis and product(s) formed. Methods described in this study provide the ability to simultaneously and independently analyze the kinetics of multiple reaction components. An unintended outcome of this work was the development of a modified Lambert W(x) which includes a parameter to account for the thermal denaturation of enzyme. The results of this study demonstrate that the action of Sinapis alba myrosinase on natural and non-natural glucosinolates is consistent under the explored range of experimental conditions and in relation to previous accounts.
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Affiliation(s)
- Chase A Klingaman
- Augustana University, Department of Chemistry, 2001 S. Summit Ave., Sioux Falls, SD 57197, USA
| | - Matthew J Wagner
- Augustana University, Department of Chemistry, 2001 S. Summit Ave., Sioux Falls, SD 57197, USA
| | - Justin R Brown
- Augustana University, Department of Chemistry, 2001 S. Summit Ave., Sioux Falls, SD 57197, USA
| | - John B Klecker
- Augustana University, Department of Chemistry, 2001 S. Summit Ave., Sioux Falls, SD 57197, USA
| | - Ethan H Pauley
- Augustana University, Department of Chemistry, 2001 S. Summit Ave., Sioux Falls, SD 57197, USA
| | - Colin J Noldner
- Augustana University, Department of Chemistry, 2001 S. Summit Ave., Sioux Falls, SD 57197, USA
| | - Jared R Mays
- Augustana University, Department of Chemistry, 2001 S. Summit Ave., Sioux Falls, SD 57197, USA.
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9
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Golmohamadi A, Morra MJ, Popova I, Nindo CI. Optimizing the use of Sinapis alba seed meal extracts as a source of thiocyanate (SCN−) for the lactoperoxidase system. Lebensm Wiss Technol 2016. [DOI: 10.1016/j.lwt.2016.05.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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10
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Houghton CA, Fassett RG, Coombes JS. Sulforaphane and Other Nutrigenomic Nrf2 Activators: Can the Clinician's Expectation Be Matched by the Reality? OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:7857186. [PMID: 26881038 PMCID: PMC4736808 DOI: 10.1155/2016/7857186] [Citation(s) in RCA: 160] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 12/06/2015] [Indexed: 12/14/2022]
Abstract
The recognition that food-derived nonnutrient molecules can modulate gene expression to influence intracellular molecular mechanisms has seen the emergence of the fields of nutrigenomics and nutrigenetics. The aim of this review is to describe the properties of nutrigenomic activators of transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2), comparing the potential for sulforaphane and other phytochemicals to demonstrate clinical efficacy as complementary medicines. Broccoli-derived sulforaphane emerges as a phytochemical with this capability, with oral doses capable of favourably modifying genes associated with chemoprevention. Compared with widely used phytochemical-based supplements like curcumin, silymarin, and resveratrol, sulforaphane more potently activates Nrf2 to induce the expression of a battery of cytoprotective genes. By virtue of its lipophilic nature and low molecular weight, sulforaphane displays significantly higher bioavailability than the polyphenol-based dietary supplements that also activate Nrf2. Nrf2 activation induces cytoprotective genes such as those playing key roles in cellular defense mechanisms including redox status and detoxification. Both its high bioavailability and significant Nrf2 inducer capacity contribute to the therapeutic potential of sulforaphane-yielding supplements.
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Affiliation(s)
- Christine A. Houghton
- School of Human Movement and Nutrition Science, The University of Queensland, Brisbane, Australia
| | - Robert G. Fassett
- School of Human Movement and Nutrition Science, The University of Queensland, Brisbane, Australia
| | - Jeff S. Coombes
- School of Human Movement and Nutrition Science, The University of Queensland, Brisbane, Australia
- *Jeff S. Coombes:
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11
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Enhancement of microwave-assisted extraction of bioactive compounds from cabbage outer leaves via the application of ultrasonic pretreatment. Sep Purif Technol 2015. [DOI: 10.1016/j.seppur.2015.02.010] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Saeed F, Arshad MU, Pasha I, Naz R, Batool R, Khan AA, Nasir MA, Shafique B. Nutritional and Phyto-Therapeutic Potential of Papaya (Carica Papaya Linn.): An Overview. INTERNATIONAL JOURNAL OF FOOD PROPERTIES 2014. [DOI: 10.1080/10942912.2012.709210] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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13
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Nehmé R, Nehmé H, Roux G, Cerniauskaite D, Morin P, Rollin P, Tatibouët A. Contactless conductivity detection for screening myrosinase substrates by capillary electrophoresis. Anal Chim Acta 2013; 807:153-8. [PMID: 24356232 DOI: 10.1016/j.aca.2013.11.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 11/04/2013] [Accepted: 11/07/2013] [Indexed: 12/27/2022]
Abstract
Myrosinase is a unique enzyme that catalyzes the hydrolysis of glucosinolates (GLS) to isothiocyanate (ITC), glucose and sulfate. Isothiocyanates display a diversified very interesting biological activity. In this study, capillary electrophoresis (CE) was used for the first time for evaluating myrosinase kinetics (maximum velocity Vmax and Michaelis-Menten constant Km) and to assess the affinity of a variety of substrates toward this enzyme. The pre-capillary approach was chosen since it is very simple to conduct. For this, the enzymatic reaction was performed in a micro-vial. The reaction mixture volume was of only 100 μL and the incubation lasted only 5 min at 37±1°C. Short-end injection of few tens of nanoliters (~25 nL) of the reaction mixture was performed which decreased analysis time without using any electroosmotic modifier. The sulfate produced was detected and quantified with a contactless capacitively coupled conductivity detector (C(4)D) allowing the evaluation of myrosinase kinetics. This study shows, that capillary electrophoresis with contactless conductivity detection can be very useful for monitoring myrosinase activity. Comparing to the conventional spectrophotometric method (1982), the CE method developed here is simple, automated, economic, rapid (incubation for few minutes) and robust. Results compared very well with those reported in literature using the conventional method. Moreover, the affinity of a variety of natural and synthetic glucosinolates toward this enzyme has been assessed for the first time.
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Affiliation(s)
- Reine Nehmé
- Institut de Chimie Organique et Analytique (ICOA), Université d'Orléans, CNRS FR 2708, UMR 7311, Orléans, France.
| | - Hala Nehmé
- Institut de Chimie Organique et Analytique (ICOA), Université d'Orléans, CNRS FR 2708, UMR 7311, Orléans, France
| | - Grégory Roux
- Institut de Chimie Organique et Analytique (ICOA), Université d'Orléans, CNRS FR 2708, UMR 7311, Orléans, France
| | - Deimante Cerniauskaite
- Institut de Chimie Organique et Analytique (ICOA), Université d'Orléans, CNRS FR 2708, UMR 7311, Orléans, France
| | - Philippe Morin
- Institut de Chimie Organique et Analytique (ICOA), Université d'Orléans, CNRS FR 2708, UMR 7311, Orléans, France
| | - Patrick Rollin
- Institut de Chimie Organique et Analytique (ICOA), Université d'Orléans, CNRS FR 2708, UMR 7311, Orléans, France
| | - Arnaud Tatibouët
- Institut de Chimie Organique et Analytique (ICOA), Université d'Orléans, CNRS FR 2708, UMR 7311, Orléans, France
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14
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Luang-In V, Narbad A, Nueno-Palop C, Mithen R, Bennett M, Rossiter JT. The metabolism of methylsulfinylalkyl- and methylthioalkyl-glucosinolates by a selection of human gut bacteria. Mol Nutr Food Res 2013; 58:875-83. [PMID: 24170324 DOI: 10.1002/mnfr.201300377] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 08/22/2013] [Accepted: 08/22/2013] [Indexed: 11/11/2022]
Abstract
SCOPE Certain myrosinase-positive human gut bacteria can metabolize glucosinolates (GSLs) to produce isothiocyanates (ITC) as chemopreventive agents. We investigated glucoerucin, glucoiberin, and glucoraphanin (present in broccoli) metabolism by human gut strains. METHODS AND RESULTS All tested bacteria metabolized glucoerucin to completion within 16 h to erucin and erucin nitrile (NIT). Lactobacillus agilis R16 metabolized only 10% of glucoiberin and glucoraphanin with no detectable products. Enterococcus casseliflavus CP1, however, metabolized 40-50% of glucoiberin and glucoraphanin producing relatively low concentrations of iberin and sulforaphane. Interestingly, Escherichia coli VL8 metabolized 80-90% of glucoiberin and glucoraphanin and also bioconverted glucoraphanin and glucoiberin to glucoerucin and glucoiberverin, respectively, producing erucin, erucin NIT, iberverin, and iberverin NIT from the two GSLs. The putative reductase enzyme in the cell-free extracts of this bacterium required both Mg(2+) and NAD(P)H as cofactors for bioconversion. The cell-free extract of E. coli VL8 containing the reductase enzyme was able to reduce both the GSL glucoraphanin and its hydrolysis product sulforaphane to glucoerucin and erucin/erucin NIT, respectively. CONCLUSION The composition and metabolic activity of the human gut bacteria can indirectly impact on the potential chemopreventive effects of GSL-derived metabolites.
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Affiliation(s)
- Vijitra Luang-In
- Imperial College London, Division of Cell and Molecular Biology, London, UK
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15
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Senthil-Kumar M, Mysore KS. Nonhost resistance against bacterial pathogens: retrospectives and prospects. ANNUAL REVIEW OF PHYTOPATHOLOGY 2013; 51:407-27. [PMID: 23725473 DOI: 10.1146/annurev-phyto-082712-102319] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Nonhost resistance is a broad-spectrum plant defense that provides immunity to all members of a plant species against all isolates of a microorganism that is pathogenic to other plant species. Upon landing on the surface of a nonhost plant species, a potential bacterial pathogen initially encounters preformed and, later, induced plant defenses. One of the initial defense responses from the plant is pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI). Nonhost plants also have mechanisms to detect nonhost-pathogen effectors and can trigger a defense response referred to as effector-triggered immunity (ETI). This nonhost resistance response often results in a hypersensitive response (HR) at the infection site. This review provides an overview of these plant defense strategies. We enumerate plant genes that impart nonhost resistance and the bacterial counter-defense strategies. In addition, prospects for application of nonhost resistance to achieve broad-spectrum and durable resistance in crop plants are also discussed.
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Affiliation(s)
- Muthappa Senthil-Kumar
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73402, USA.
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16
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Listeria monocytogenes inhibition by defatted mustard meal-based edible films. Int J Food Microbiol 2012; 153:99-105. [DOI: 10.1016/j.ijfoodmicro.2011.10.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 10/15/2011] [Accepted: 10/25/2011] [Indexed: 11/17/2022]
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17
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Vanden Bussche J, Kiebooms JAL, De Clercq N, Deceuninck Y, Le Bizec B, De Brabander HF, Vanhaecke L. Feed or food responsible for the presence of low-level thiouracil in urine of livestock and humans? JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2011; 59:5786-5792. [PMID: 21504236 DOI: 10.1021/jf200556x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In recent years, questions have been raised on the possible semi-endogenous status of the alleged xenobiotic thyreostatic drug thiouracil; thiouracil has been detected in the urine of various animals (livestock and domesticated) at concentrations between 1 and 10 μg L(-1) and also in human urine. Although several studies suggest Brassicaceae-derived feed as potential origin, no traces of thiouracil have been detected in feed so far. Therefore, the aim of this study was to elucidate the origin of thiouracil in the urine of livestock and humans. To this purpose various Brassicaceae feed and food sources (e.g., rapeseed, rapeseed coarse meal, cabbage, cauliflower, broccoli) were investigated for the presence of thiouracil. In addition, the impact of the Brassicaceae-related β-thioglucosidase enzyme was evaluated. This myrosinase enzyme appeared to be crucial, because without its catalyzed hydrolysis no thiouracil could be detected in the various Brassicaceae-derived samples. Therefore, a sample pretreatment with incorporated enzymatic hydrolysis was developed after ensuring the quality performance of the extracted myrosinase mixture with a single-point glucose assay. Upon enzymatic hydrolysis and LC-MS(2) analysis, thiouracil was successfully detected in samples of traditional rapeseed, rapeseed-'00' variety coarse meal (values of erucic acid <2% and glucosinolates <25 μmol g(-1)), and rapeseed cake at 1.5, 1.6, and 0.4 μg kg(-1), respectively. As for the food samples, broccoli and cauliflower displayed thiouracil concentrations of 6.0 and <1.0 μg kg(-1), respectively. To the best of the authors' knowledge this study is the first to report the presence of naturally occurring thiouracil in feed and food samples. Future research should investigate the pathway of thiouracil formation and identify its possible precursors.
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Andersson D, Chakrabarty R, Bejai S, Zhang J, Rask L, Meijer J. Myrosinases from root and leaves of Arabidopsis thaliana have different catalytic properties. PHYTOCHEMISTRY 2009; 70:1345-54. [PMID: 19703694 DOI: 10.1016/j.phytochem.2009.07.036] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2009] [Revised: 07/17/2009] [Accepted: 07/20/2009] [Indexed: 05/20/2023]
Abstract
Myrosinases (EC 3.2.1.147) are beta-thioglucoside glucosidases present in Brassicaceae plants. These enzymes serve to protect plants against pathogens and insect pests by initiating breakdown of the secondary metabolites glucosinolates into toxic products. Several forms of myrosinases are present in plants but the properties and role of different isoenzymes are not well understood. The dicot plant model organism Arabidopsis thaliana seems to contain six myrosinase genes (TGG1-TGG6). In order to compare the different myrosinases, cDNAs corresponding to TGG1 from leaves and TGG4 and TGG5 from roots were cloned and overexpressed in Pichia pastoris. The His-tagged recombinant proteins were purified using affinity chromatography and the preparations were homogenous according to SDS-PAGE analysis. Myrosinase activity was confirmed for all forms and compared with respect to catalytic activity towards the allyl-glucosinolate sinigrin. There was a 22-fold difference in basal activity among the myrosinases. The enzymes were active in a broad pH range, are rather thermostable and active in a wide range of salt concentrations but sensitive to high salt concentrations. The myrosinases showed different activation-inhibition responses towards ascorbic acid with maximal activity around 0.7-1 mM. No activity was registered towards desulphosinigrin and this compound did not inhibit myrosinase activity towards sinigrin. All myrosinases also displayed O-beta-glucosidase activity, although with lower efficiency compared to the myrosinase activity. The differences in catalytic properties among myrosinase isozymes for function in planta are discussed.
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Affiliation(s)
- Derek Andersson
- Department of Plant Biology and Forest Genetics, Uppsala BioCenter, Box 7080, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden
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19
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Rossetto MRM, Oliveira do Nascimento JR, Purgatto E, Fabi JP, Lajolo FM, Cordenunsi BR. Benzylglucosinolate, benzylisothiocyanate, and myrosinase activity in papaya fruit during development and ripening. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2008; 56:9592-9599. [PMID: 18826320 DOI: 10.1021/jf801934x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Papaya is a climacteric fruit that has high amounts of benzylglucosinolates (BG) and benzylisothiocyanates (BITC), but information regarding levels of BG or BITC during fruit development and ripening is limited. Because BG and BITC are compounds of importance from both a nutritional and a crop yield standpoint, the aim of this work was to access data on the distribution and changes of BG and BITC levels during fruit development and ripening. BG and BITC levels were quantified in peel, pulp, and seeds of papaya fruit. Volatile BITC was also verified in the internal cavity of the fruit during ripening. The influence of the ethylene in BG and BITC levels and mirosinase activity was tested by exposing mature green fruits to ethylene and 1-methylcyclopropene (1-MCP). The highest BG levels were detected in seeds, followed by the peel and pulp being decreased in all tissues during fruit development. Similarly, the levels of BITC were much higher in the seeds than the peel and pulp. The levels of BG for control and ethylene-treated fruit were very similar, increasing in the pulp and peel during late ripening but not changing significantly in seeds. On the other hand, fruit exposed to 1-MCP showed a decrease in BG amount in the pulp and accumulation in seed. The treatments did not result in clear differences regarding the amount of BITC in the pulp and peel of the fruit. According to the results, ethylene does not have a clear effect on BITC accumulation in ripening papaya fruit. The fact that BG levels in the pulp did not decrease during ripening, regardless of the treatment employed, and that papaya is consumed mainly as fresh fruit, speaks in favor of this fruit as a good dietary source for glucosinolate and isothiocyanates.
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Affiliation(s)
- Maria Rosecler Miranda Rossetto
- Laboratorio de Quimica, Bioquimica e Biologia Molecular de Alimentos, Departamento de Alimentos e Nutricao Experimental, FCF, Universidade de Sao Paulo, Avenida Lineu Prestes 580, Bloco 14, CEP 05508-900, Sao Paulo-SP, Brazil
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20
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Shen H, Byers LD. Thioglycoside hydrolysis catalyzed by β-glucosidase. Biochem Biophys Res Commun 2007; 362:717-20. [PMID: 17727815 DOI: 10.1016/j.bbrc.2007.08.043] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Accepted: 08/09/2007] [Indexed: 11/20/2022]
Abstract
Sweet almond beta-glucosidase (EC 3.2.1.21) has been shown to have significant thioglycohydrolase activity. While the Km values for the S- and O-glycosides are similar, the k(cat) values are about 1000-times lower for the S-glycosides. Remarkably, the pH-profile for k(cat)/Km for hydrolysis of p-nitrophenyl thioglucoside (pNPSG) shows the identical dependence on a deprotonated carboxylate (pKa 4.5) and a protonated group (pKa 6.7) as does the pH-profile for hydrolysis of the corresponding O-glycoside. Not surprisingly, in spite of the requirement for the presence of this protonated group in catalytically active beta-glucosidase, thioglucoside hydrolysis does not involve general acid catalysis. There is no solvent kinetic isotope effect on the enzyme-catalyzed hydrolysis of pNPSG.
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Affiliation(s)
- Hong Shen
- Department of Chemistry, Tulane University, New Orleans, LA 70118, USA
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21
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Vocadlo DJ, Wicki J, Rupitz K, Withers SG. Mechanism of Thermoanaerobacterium saccharolyticum beta-xylosidase: kinetic studies. Biochemistry 2002; 41:9727-35. [PMID: 12146938 DOI: 10.1021/bi020077v] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The catalytic mechanism of Thermoanaerobacterium saccharolyticum beta-xylosidase (XynB) from family 39 of glycoside hydrolases has been subjected to a detailed kinetic investigation using a range of substrates. The enzyme exhibits a bell-shaped pH dependence of k(cat)/K(m), reflecting apparent pK(a) values of 4.1 and 6.8. The k(cat) and k(cat)/K(m) values for a series of aryl xylosides have been measured and used to construct two Brønsted plots. The plot of log(k(cat)/K(m)) against the pK(a) of the leaving group reveals a significant correlation (beta(lg) = -0.97, r(2) = 0.94, n = 8), indicating that fission of the glycosidic bond is significantly advanced in the transition state leading to the formation of the xylosyl-enzyme intermediate. The large negative value of the slope indicates that there is relatively little proton donation to the glycosidic oxygen in the transition state. A biphasic, concave-downward plot of log(k(cat)) against pK(a) provides good evidence for a two-step double-displacement mechanism involving a glycosyl-enzyme intermediate. For activated leaving groups (pK(a) < 9), the breakdown of the xylosyl-enzyme intermediate is the rate-determining step, as indicated by the absence of any effect of the pK(a) of the leaving group on log(k(cat)) (beta(lg) approximately 0). However, a strong dependence of the first-order rate constant on the pK(a) value of relatively poor leaving groups (pK(a) > 9) suggests that the xylosylation step is rate-determining for these substrates. Support for the dexylosylation chemical step being rate-determining for activated substrates comes from nucleophilic competition experiments in which addition of dithiothreitol results in an increase in turnover rates. Normal secondary alpha-deuterium kinetic isotope effects ((alpha-D)(V) or (alpha-D)(V/K) = 1.08-1.10) for three different substrates of widely varying pK(a) value (5.15-9.95) have been measured and these reveal that the transition states leading to the formation and breakdown of the intermediate are similar and both steps involve rehybridization of C1 from sp(3) to sp(2). These results are consistent only with "exploded" transition states, in which the saccharide moiety bears considerable positive charge, and the intermediate is a covalent acylal-ester where C1 is sp(3) hybridized.
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Affiliation(s)
- David J Vocadlo
- Protein Engineering Network of Centres of Excellence of Canada, Vancouver, British Columbia, Canada V6T 1Z1
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22
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Wilson RK, Kwan TK, Kwan CY, Sorger GJ. Effects of papaya seed extract and benzyl isothiocyanate on vascular contraction. Life Sci 2002; 71:497-507. [PMID: 12052434 DOI: 10.1016/s0024-3205(02)01708-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To investigate their potentially toxic effects on mammalian vascular smooth muscle, pentane extracts of papaya seeds and the chief active ingredient in the extracts, benzyl isothiocyanate (BITC), were tested for their effects on the contraction of strips of dog carotid artery. BITC and the papaya seed extract caused relaxation when added to tissue strips that had been pre-contracted with phenylephrine (PE). Incubation of the tissue with papaya seed extract or BITC caused inhibition of contraction when the strips were subsequently contracted with KCl or PE. This relaxation and inhibition of contraction did not appear to be endothelium-dependent, as endothelium-denuded rings showed the same degree of relaxation or inhibition of contraction in response to the preparations/drugs as those with the endothelium intact. The effects of both BITC and the extract were irreversible, i.e., the tissue did not recover to normal contractile ability after extensive washing. Exposure of the tissue to the papaya seed extract caused slower relaxation of the tissue, compared to controls, both after contraction with PE and subsequent addition of carbachol (CCh), and after contraction with KCl and then washing. Calcium imaging studies using cultured endothelial cells showed strong influxes of Ca2+ into the cells in response to addition of the papaya seed extract. We conclude that these extracts, when present in high concentration, are cytotoxic by increasing the membrane permeability to Ca2+, and that the vascular effects of papaya seed extracts are consistent with the notion that BITC is the chief bio-active ingredient.
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MESH Headings
- Animals
- Calcium/metabolism
- Carbachol/pharmacology
- Cardiotonic Agents/pharmacology
- Carica/chemistry
- Carotid Arteries/drug effects
- Cattle
- Cells, Cultured
- Dogs
- Endothelium, Vascular/cytology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Humans
- In Vitro Techniques
- Isothiocyanates/pharmacology
- Muscle Contraction/drug effects
- Muscle Contraction/physiology
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Phenylephrine/pharmacology
- Plant Extracts/pharmacology
- Potassium Chloride/pharmacology
- Seeds/chemistry
- Vasoconstriction/drug effects
- Vasoconstrictor Agents/pharmacology
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Affiliation(s)
- Ruth K Wilson
- Smooth Muscle Research Program, Department of Medicine, HSC 4N40, McMaster University, 1200 Main Street W., L8N 3Z5, Hamilton, ON, Canada
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Kermanshai R, McCarry BE, Rosenfeld J, Summers PS, Weretilnyk EA, Sorger GJ. Benzyl isothiocyanate is the chief or sole anthelmintic in papaya seed extracts. PHYTOCHEMISTRY 2001; 57:427-435. [PMID: 11393524 DOI: 10.1016/s0031-9422(01)00077-2] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Papaya (Carica papaya) seeds were extracted in an aqueous buffer or in organic solvents, fractionated by chromatography on silica and aliquots tested for anthelmintic activity by viability assays using Caenorhabditis elegans. For all preparations and fractions tested, anthelmintic activity and benzyl isothiocyanate content correlated positively. Aqueous extracts prepared from heat-treated seeds had no anthelmintic activity or benzyl isothiocyanate content although both appeared when these extracts were incubated with a myrosinase-containing fraction prepared from papaya seeds. A 10 h incubation of crude seed extracts at room temperature led to a decrease in anthelmintic activity and fractionated samples showed a lower benzyl isothiocyanate content relative to non-incubated controls. Benzyl thiocyanate, benzyl cyanide, and benzonitrile were not detected in any preparations and cyanogenic glucosides. which were present, could not account for the anthelmintic activity detected. Thus, our results are best explained if benzyl isothiocyanate is the predominant or sole anthelmintic agent in papaya seed extracts regardless of how seeds are extracted.
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Affiliation(s)
- R Kermanshai
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
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24
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Metzler DE, Metzler CM, Sauke DJ. Some Pathways of Carbohydrate Metabolism. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50023-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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25
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Burmeister WP, Cottaz S, Rollin P, Vasella A, Henrissat B. High resolution X-ray crystallography shows that ascorbate is a cofactor for myrosinase and substitutes for the function of the catalytic base. J Biol Chem 2000; 275:39385-93. [PMID: 10978344 DOI: 10.1074/jbc.m006796200] [Citation(s) in RCA: 138] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Myrosinase, an S-glycosidase, hydrolyzes plant anionic 1-thio-beta-d-glucosides (glucosinolates) considered part of the plant defense system. Although O-glycosidases are ubiquitous, myrosinase is the only known S-glycosidase. Its active site is very similar to that of retaining O-glycosidases, but one of the catalytic residues in O-glycosidases, a carboxylate residue functioning as the general base, is replaced by a glutamine residue. Myrosinase is strongly activated by ascorbic acid. Several binary and ternary complexes of myrosinase with different transition state analogues and ascorbic acid have been analyzed at high resolution by x-ray crystallography along with a 2-deoxy-2-fluoro-glucosyl enzyme intermediate. One of the inhibitors, d-gluconhydroximo-1,5-lactam, binds simultaneously with a sulfate ion to form a mimic of the enzyme-substrate complex. Ascorbate binds to a site distinct from the glucose binding site but overlapping with the aglycon binding site, suggesting that activation occurs at the second step of catalysis, i.e. hydrolysis of the glycosyl enzyme. A water molecule is placed perfectly for activation by ascorbate and for nucleophilic attack on the covalently trapped 2-fluoro-glucosyl-moiety. Activation of the hydrolysis of the glucosyl enzyme intermediate is further evidenced by the observation that ascorbate enhances the rate of reactivation of the 2-fluoro-glycosyl enzyme, leading to the conclusion that ascorbic acid substitutes for the catalytic base in myrosinase.
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Affiliation(s)
- W P Burmeister
- European Synchrotron Radiation Facility and Forschungszentrum Jülich, BP 220, F-38043 Grenoble cedex, France.
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Shikita M, Fahey JW, Golden TR, Holtzclaw WD, Talalay P. An unusual case of 'uncompetitive activation' by ascorbic acid: purification and kinetic properties of a myrosinase from Raphanus sativus seedlings. Biochem J 1999; 341 ( Pt 3):725-32. [PMID: 10417337 PMCID: PMC1220411 DOI: 10.1042/0264-6021:3410725] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Myrosinase (thioglucoside glucohydrolase; EC 3.2.3.1) is a plant enzyme that hydrolyses glucosinolates, principally to isothiocyanates. Myrosinase was purified to homogeneity in good yield from 8-day-old seedlings of Raphanus sativus (daikon) using a four-step procedure involving chromatographies on anion exchange, hydrophobic Phenyl-Sepharose, gel filtration and concanavalin A-Sepharose. In order to stabilize the enzyme and to avoid excessive peak broadening during chromatography, 30% (v/v) glycerol was added to dialysis and chromatography buffers. The purified enzyme was eluted as a single peak from a gel-filtration sizing column with an apparent molecular mass of 120 kDa. The enzyme was resolved into two subunits with molecular masses of 61 and 62 kDa by SDS/PAGE. Ascorbic acid activated the purified enzyme more than 100-fold. The V(max) and K(m) values for the hydrolysis of allyl glucosinolate (sinigrin) were 2.06 micromol/min per mg of protein and 23 microM in the absence of ascorbate and 280 micromol/min per mg of protein and 250 microM in the presence of 500 microM ascorbate, respectively. As the ascorbate concentration was increased from 50 to 500 microM, the V(max) and K(m) values increased in parallel, and thus the V(max)/K(m) ratio remained constant. Similarly, raising the concentrations of sinigrin increased the concentration of ascorbic acid required for half-maximal activation (K(a)). At a sinigrin concentration of 250 microM, the K(a) for ascorbic acid was 55 microM. Sulphate, a reaction product, was a competitive inhibitor of activity, having a K(i) of 60 mM with respect to sinigrin and of 27 mM with respect to ascorbate. Thus activation of myrosinase from R. sativus by ascorbic acid exemplifies an unusual and possibly unique example of linear 'uncompetitive activation' (i.e. a proportionate increase in V(max) and K(m)) of an enzyme. The enzyme also had beta-glucosidase activity and hydrolysed p-nitrophenyl-beta-d-glucopyranoside.
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Affiliation(s)
- M Shikita
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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27
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Burmeister WP, Cottaz S, Driguez H, Iori R, Palmieri S, Henrissat B. The crystal structures of Sinapis alba myrosinase and a covalent glycosyl-enzyme intermediate provide insights into the substrate recognition and active-site machinery of an S-glycosidase. Structure 1997; 5:663-75. [PMID: 9195886 DOI: 10.1016/s0969-2126(97)00221-9] [Citation(s) in RCA: 201] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Myrosinase is the enzyme responsible for the hydrolysis of a variety of plant anionic 1-thio-beta-D-glucosides called glucosinolates. Myrosinase and glucosinolates, which are stored in different tissues of the plant, are mixed during mastication generating toxic by-products that are believed to play a role in the plant defence system. Whilst O-glycosidases are extremely widespread in nature, myrosinase is the only known S-glycosidase. This intriguing enzyme, which shows sequence similarities with O-glycosidases, offers the opportunity to analyze the similarities and differences between enzymes hydrolyzing S- and O-glycosidic bonds. RESULTS The structures of native myrosinase from white mustard seed (Sinapis alba) and of a stable glycosyl-enzyme intermediate have been solved at 1.6 A resolution. The protein folds into a (beta/alpha)8-barrel structure, very similar to that of the cyanogenic beta-glucosidase from white clover. The enzyme forms a dimer stabilized by a Zn2+ ion and is heavily glycosylated. At one glycosylation site the complete structure of a plant-specific heptasaccharide is observed. The myrosinase structure reveals a hydrophobic pocket, ideally situated for the binding of the hydrophobic sidechain of glucosinolates, and two arginine residues positioned for interaction with the sulphate group of the substrate. With the exception of the replacement of the general acid/base glutamate by a glutamine residue, the catalytic machinery of myrosinase is identical to that of the cyanogenic beta-glucosidase. The structure of the glycosyl-enzyme intermediate shows that the sugar ring is bound via an alpha-glycosidic linkage to Glu409, the catalytic nucleophile of myrosinase. CONCLUSIONS The structure of myrosinase shows features which illustrate the adaptation of the plant enzyme to the dehydrated environment of the seed. The catalytic mechanism of myrosinase is explained by the excellent leaving group properties of the substrate aglycons, which do not require the assistance of an enzymatic acid catalyst. The replacement of the general acid/base glutamate of O-glycosidases by a glutamine residue in myrosinase suggests that for hydrolysis of the glycosyl-enzyme, the role of this residue is to ensure a precise positioning of a water molecule rather than to provide general base assistance.
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Affiliation(s)
- W P Burmeister
- European Synchrotron Radiation Facility (ESRF), BP 220, F-38043 Grenoble cedex, France.
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Cottaz S, Rollin P, Driguez H. Synthesis of 2-deoxy-2-fluoro-glucotropaeolin, a thioglucosidase inhibitor. Carbohydr Res 1997. [DOI: 10.1016/s0008-6215(96)00294-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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29
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Cottaz S, Henrissat B, Driguez H. Mechanism-based inhibition and stereochemistry of glucosinolate hydrolysis by myrosinase. Biochemistry 1996; 35:15256-9. [PMID: 8952475 DOI: 10.1021/bi9622480] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Myrosinase is a particular glucosidase which hydrolyzes a variety of plant 1-thio-beta-D-glucosides known as the glucosinolates. This enzyme, which is the only glycosidase able to hydrolyze these naturally occurring thioglucosides, has been found previously to display strong sequence similarities with family 1 O-glycosidases. Myrosinase therefore offers the opportunity to compare the mechanism of enzymatic cleavage of S- vs O-glycosidic bonds. The stereochemistry of hydrolysis of sinigrin by Sinapis alba myrosinase was followed by 1H NMR and the enzyme was found to operate with a mechanism retaining the anomeric configuration at the cleavage point exactly like the related O-glycosidases found in family 1. Myrosinase was readily inactivated by 2-deoxy-2-fluoroglucotropaeolin with inactivation kinetic parameters of Ki = 0.9 mM and ki = 0.083 min-1. Reactivation kinetic parameters were determined in buffer only, with k(react) = 0.015 h-1 and t1/2 = 46 h, and also in the presence of acceptors of transglycosylation. No significant changes were observed in the presence of methyl beta-D-glucoside, but with azide anion the half-life of reactivation was found to be reduced to t1/2 = 20 h. These results suggest that myrosinase inhibition by 2-deoxy-2-fluoroglucotropaeolin occurs via the accumulation of a long-life glucosyl-enzyme intermediate and that the catalytic machinery of the enzyme is composed of only one catalytic residue, a nucleophilic glutamate, while the acid catalyst residue found in the corresponding O-glycosidases is missing.
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Affiliation(s)
- S Cottaz
- Centre de Recherches sur les Macromolécules Végétales, Centre National de la Recherche Scientifique, Grenoble, France
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