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Gattani A, Agrawal A, Khan MH, Gupta R, Singh P. Evaluation of catalytic activity of human and animal origin viral neuraminidase: Current prospect. Anal Biochem 2023; 671:115157. [PMID: 37061113 DOI: 10.1016/j.ab.2023.115157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 04/12/2023] [Indexed: 04/17/2023]
Abstract
With the exception of plants, almost all living organisms synthesize neuraminidase/sialidase. It is a one among the crucial proteins that controls how virulent a microorganism is. An essential enzyme in orthomyxoviruses and paramyxoviruses that destroys receptors is neuraminidase. It plays a number of roles throughout the viral life cycle in addition to one that involves the release of progeny virus particles. This protein is an important target for therapeutic interventions and diagnostic assays. Neuraminidase inhibitors effectively prevent the spread of disease and viral infection. Sensitive, quick, and inexpensive high throughput assays are needed to screen for specific neuraminidase inhibitory chemicals. To characterize the neuraminidase catalytic activity, however, the traditional assays are still the most common in laboratories. This review gives a brief overview of these neuraminidase assays and recent, innovative developments, particularly those involving biosensors.
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Affiliation(s)
- Anil Gattani
- Department of Veterinary Biochemistry, College of Veterinary Science & Animal Husbandry, Jabalpur, M.P, India.
| | - Aditya Agrawal
- Department of Veterinary Biochemistry, College of Veterinary Science & Animal Husbandry, Rewa, M.P, India
| | - M Hira Khan
- Department of Veterinary Biochemistry, College of Veterinary Science & Animal Husbandry, Jabalpur, M.P, India
| | - Rohini Gupta
- Department of Medicine, College of Veterinary Science & Animal Husbandry, Jabalpur, M.P, India
| | - Praveen Singh
- Division of Biochemistry, ICAR-Indian Veterinary Research Institute Izatnagar, 243122, Bareilly, UP, India; Biophysics Section, ICAR-Indian Veterinary Research Institute Izatnagar, 243122, Bareilly, UP, India
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Yu ACY, Volkers G, Jongkees SAK, Worrall LJ, Withers SG, Strynadka NCJ. Crystal structure of the Propionibacterium acnes surface sialidase, a drug target for P. acnes-associated diseases. Glycobiology 2021; 32:162-170. [PMID: 34792586 DOI: 10.1093/glycob/cwab094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/28/2021] [Accepted: 05/19/2021] [Indexed: 11/12/2022] Open
Abstract
Propionibacterium acnes, though generally considered part of the normal flora of human skin, is an opportunistic pathogen associated with acne vulgaris as well as other diseases, including endocarditis, endophthalmitis and prosthetic joint infections. Its virulence potential is also supported by knowledge gained from its sequenced genome. Indeed, a vaccine targeting a putative cell wall-anchored P. acnes sialidase has been shown to suppress cytotoxicity and pro-inflammatory cytokine release induced by the organism, and is proposed as an alternative treatment for P. acnes-associated diseases. Here, we report the crystal structures of the surface sialidase and its complex with the transition-state mimic Neu5Ac2en. Our structural and kinetic analyses, together with insight from a glycan array screen, which probes subtle specificities of the sialidase for α-2,3-sialosides, provide a basis for the structure-based design of novel small-molecule therapeutics against P. acnes infections.
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Affiliation(s)
- Angel C Y Yu
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada.,Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, 2350 Health Sciences Mall, V6T 1Z3, Canada
| | - Gesa Volkers
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada.,Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, 2350 Health Sciences Mall, V6T 1Z3, Canada
| | - Seino A K Jongkees
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada
| | - Liam J Worrall
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada.,Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, 2350 Health Sciences Mall, V6T 1Z3, Canada
| | - Stephen G Withers
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada.,Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada
| | - Natalie C J Strynadka
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada.,Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, 2350 Health Sciences Mall, V6T 1Z3, Canada
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Intragastric delivery of recombinant Lactococcus lactis displaying ectodomain of influenza matrix protein 2 (M2e) and neuraminidase (NA) induced focused mucosal and systemic immune responses in chickens. Mol Immunol 2019; 114:497-512. [PMID: 31518854 DOI: 10.1016/j.molimm.2019.08.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 05/25/2019] [Accepted: 08/20/2019] [Indexed: 01/08/2023]
Abstract
Compounding with the problem of frequent antigenic shift and occasional drift of the segmented genome of Avian Influenza Virus (AIV), vaccines based on major surface glycoproteins such as haemagglutinin (HA) to counter heterosubtypic AIV infection in chickens remain unsuccessful. In contrast, neuraminidase (NA), the second most abundant surface glycoprotein present in viral capsid is less mutable and, in some instances, successful in eliciting inter-species cross-reactive antibody responses. However, without selective activation of B-cells and T-cells, the ability of NA to induce strong cell mediated immune responses is limited, thus NA based vaccines cannot singularly address the risk of virus escape from host defence. To this end, the highly conserved ectodomain of influenza matrix protein-2 (M2e) has emerged as an attractive cross-protective vaccine target. The present study describes the potential of recombinant Lactococcus lactis (rL. lactis) in expressing functional influenza NA or M2e proteins and conferring effective mucosal and systemic immune responses in the intestine as well as in the upper respiratory airways (trachea) of chickens. In addition, lavages collected from trachea and intestine of birds administered with rL. lactis expressing influenza NA or M2e protein were found to protect MDCK cells against avian influenza type A/PR/8/34 (H1N1) virus challenge. Although minor, the differences in the expression of pro-inflammatory cytokines gene transcripts targeted in this study among the birds administered with either empty or rL. lactis could be attributed to the activation of innate response by L. lactis.
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Hľasová Z, Košík I, Ondrejovič M, Miertuš S, Katrlík J. Methods and Current Trends in Determination of Neuraminidase Activity and Evaluation of Neuraminidase Inhibitors. Crit Rev Anal Chem 2018; 49:350-367. [DOI: 10.1080/10408347.2018.1531692] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Zuzana Hľasová
- Department of Biotechnology, Faculty of Natural Sciences of University Ss. Cyril and Methodius, Trnava, Slovakia
| | - Ivan Košík
- Cellular Biology Section, Laboratory of Viral Diseases, NIAID, Bethesda, Maryland, USA
| | - Miroslav Ondrejovič
- Department of Biotechnology, Faculty of Natural Sciences of University Ss. Cyril and Methodius, Trnava, Slovakia
| | - Stanislav Miertuš
- Department of Biotechnology, Faculty of Natural Sciences of University Ss. Cyril and Methodius, Trnava, Slovakia
- International Centre for Applied Research and Sustainable Technology, Bratislava, Slovakia
| | - Jaroslav Katrlík
- Department of Glycobiotechnology, Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia
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Wang X, Long H, Shen D, Liu L. Cloning, expression, and characterization of a novel sialidase from Brevibacterium casei. Biotechnol Appl Biochem 2016; 64:195-200. [PMID: 26748450 DOI: 10.1002/bab.1475] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 01/04/2016] [Indexed: 11/08/2022]
Abstract
The sialidase gene from Brevibacterium casei was cloned in pET28a and overexpressed as a histidine-tagged protein in Escherichia coli BL21(DE3). The histidine-tagged sialidase protein was purified and characterized from the crude cell extracts of isopropyl-β-d-thiogalactopyranoside-induced cells using Ni-NTA agarose chromatography. SDS-PAGE using the purified sialidase indicated a single band at 116 kDa. This sialidase showed maximum activity at a pH of 5.5 and temperature of 37 °C. The kinetic parameters Km and Vmax for the artificial substrate 2'-(4-methylumbelliferyl)-α-d-N-acetyl-neuraminic acid sodium salt hydrate were 1.69 × 10-3 mM and 244 mmol·Min-1 ·mg-1 , respectively. The sialidase may catalyze the hydrolysis of terminal sialic acids linked by the α-(2,3) and α-(2,8) linkage of polysialogangliosides, but it does not act on monosialotetrahexosylganglioside (GM1), which offers it a great potential for commercially producing GM1 from polysialogangliosides.
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Affiliation(s)
- Xuedong Wang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, People's Republic of China
| | - Hui Long
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, People's Republic of China
| | - Danhong Shen
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, People's Republic of China
| | - Long Liu
- Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, People's Republic of China
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Fluorescently labelled glycans and their applications. Glycoconj J 2015; 32:559-74. [DOI: 10.1007/s10719-015-9611-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Revised: 07/13/2015] [Accepted: 07/15/2015] [Indexed: 01/20/2023]
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Burke HM, Gunnlaugsson T, Scanlan EM. Recent advances in the development of synthetic chemical probes for glycosidase enzymes. Chem Commun (Camb) 2015; 51:10576-88. [PMID: 26051717 DOI: 10.1039/c5cc02793d] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The emergence of synthetic glycoconjugates as chemical probes for the detection of glycosidase enzymes has resulted in the development of a range of useful chemical tools with applications in glycobiology, biotechnology, medical and industrial research. Critical to the function of these probes is the preparation of substrates containing a glycosidic linkage that when activated by a specific enzyme or group of enzymes, irreversibly releases a reporter molecule that can be detected. Starting from the earliest examples of colourimetric probes, increasingly sensitive and sophisticated substrates have been reported. In this review we present an overview of the recent advances in this field, covering an array of strategies including chromogenic and fluorogenic substrates, lanthanide complexes, gels and nanoparticles. The applications of these substrates for the detection of various glycosidases and the scope and limitations for each approach are discussed.
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Affiliation(s)
- Helen M Burke
- School of Chemistry and Trinity Biomedical Sciences Institute, Trinity College, Pearse St, Dublin 2, Ireland.
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Abstract
Fusobacterium nucleatum is a ubiquitous member of the human oral flora and is associated with the development of periodontitis and a variety of other types of polymicrobial infections of the mucosa. In the oral cavity, this species is one of the few that is prevalent in both healthy and diseased subgingival plaque. Using microarray analysis, we examined the transcriptional response of F. nucleatum subspecies nucleatum to whole blood in order to identify some of the genetic responses that might occur during the transition from health to disease. From these studies, we identified a sialic acid catabolism operon that was induced by the presence of blood. We subsequently confirmed that this operon was inducible by the presence of synthetic sialic acid, but we found no evidence suggesting sialic acid was used as a major carbon source. However, this organism was found to possess a de novo synthesized surface sialylation ability that is widely conserved among the various F. nucleatum subspecies as well as in F. periodonticum. We provide evidence that fusobacterial sialylation does occur in the oral cavity irrespective of health status. Interestingly, only a minority of fusobacterial cells exhibit surface sialylation within dental plaque, whereas most cells are uniformly sialylated when grown in pure culture. The implications of these results are discussed.
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Woo HS, Kim DW, Curtis-Long MJ, Lee BW, Lee JH, Kim JY, Kang JE, Park KH. Potent inhibition of bacterial neuraminidase activity by pterocarpans isolated from the roots of Lespedeza bicolor. Bioorg Med Chem Lett 2011; 21:6100-3. [DOI: 10.1016/j.bmcl.2011.08.046] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Revised: 08/02/2011] [Accepted: 08/10/2011] [Indexed: 10/17/2022]
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Abstract
The early detection of many human diseases is crucial if they are to be treated successfully. Therefore, the development of imaging techniques that can facilitate early detection of disease is of high importance. Changes in the levels of enzyme expression are known to occur in many diseases, making their accurate detection at low concentrations an area of considerable active research. Activatable fluorescent probes show immense promise in this area. If properly designed they should exhibit no signal until they interact with their target enzyme, reducing the level of background fluorescence and potentially endowing them with greater sensitivity. The mechanisms of fluorescence changes in activatable probes vary. This review aims to survey the field of activatable probes, focusing on their mechanisms of action as well as illustrating some of the in vitro and in vivo settings in which they have been employed.
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Affiliation(s)
- Christopher R Drake
- Department of Radiology and Biomedical Imaging, University of California San Francisco, 185 Berry Street, Suite 350, Box 0946, San Francisco, CA, 94107, USA
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Morley TJ, Willis LM, Whitfield C, Wakarchuk WW, Withers SG. A new sialidase mechanism: bacteriophage K1F endo-sialidase is an inverting glycosidase. J Biol Chem 2009; 284:17404-10. [PMID: 19411257 PMCID: PMC2719380 DOI: 10.1074/jbc.m109.003970] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Indexed: 12/15/2022] Open
Abstract
Bacteriophages specific for Escherichia coli K1 express a tailspike protein that degrades the polysialic acid coat of E. coli K1 that is essential for bacteriophage infection. This enzyme is specific for polysialic acid and is a member of a family of endo-sialidases. This family is unusual because all other previously reported sialidases outside of this family are exo- or trans-sialidases. The recently determined structure of an endo-sialidase derived from bacteriophage K1F (endoNF) revealed an active site that lacks a number of the residues that are conserved in other sialidases, implying a new, endo-sialidase-specific catalytic mechanism. Using synthetic trifluoromethylumbelliferyl oligosialoside substrates, kinetic parameters for hydrolysis at a single cleavage site were determined. Measurement of kcat/Km at a series of pH values revealed a dependence on a single protonated group of pKa 5. Mutation of a putative active site acidic residue, E581A, resulted in complete loss of sialidase activity. Direct 1H NMR analysis of the hydrolysis of trifluoromethylumbelliferyl sialotrioside revealed that endoNF is an inverting sialidase. All other wild type sialidases previously reported are retaining glycosidases, implying a new mechanism of sialidase action specific to this family of endo-sialidases.
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Affiliation(s)
- Thomas J. Morley
- From the Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1
| | - Lisa M. Willis
- the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, and
| | - Chris Whitfield
- the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, and
| | - Warren W. Wakarchuk
- the Institute for Biological Sciences, National Research Council Canada, Ottawa, Ontario K1A 0R6, Canada
| | - Stephen G. Withers
- From the Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1
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Ryu YB, Curtis-Long MJ, Kim JH, Jeong SH, Yang MS, Lee KW, Lee WS, Park KH. Pterocarpans and flavanones from Sophora flavescens displaying potent neuraminidase inhibition. Bioorg Med Chem Lett 2008; 18:6046-9. [DOI: 10.1016/j.bmcl.2008.10.033] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2008] [Revised: 09/06/2008] [Accepted: 10/08/2008] [Indexed: 11/15/2022]
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13
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Damager I, Buchini S, Amaya MF, Buschiazzo A, Alzari P, Frasch AC, Watts A, Withers SG. Kinetic and mechanistic analysis of Trypanosoma cruzi trans-sialidase reveals a classical ping-pong mechanism with acid/base catalysis. Biochemistry 2008; 47:3507-12. [PMID: 18284211 DOI: 10.1021/bi7024832] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The trans-sialidase from Trypanosoma cruzi catalyzes the transfer of a sialic acid moiety from sialylated donor substrates to the terminal galactose moiety of lactose and lactoside acceptors to yield alpha-(2,3)-sialyllactose or its derivatives with net retention of anomeric configuration. Through kinetic analyses in which the concentrations of two different donor aryl alpha-sialoside substrates and the acceptor substrate lactose were independently varied, we have demonstrated that this enzyme follows a ping-pong bi-bi kinetic mechanism. This is supported for both the native enzyme and a mutant (D59A) in which the putative acid/base catalyst has been replaced by the demonstration of the half-reaction in which a sialyl-enzyme intermediate is formed. Mass spectrometric analysis of the protein directly demonstrates the formation of a covalent intermediate, while the observation of release of a full equivalent of p-nitrophenol by the mutant in a pre-steady state burst provides further support. The active site nucleophile is confirmed to be Tyr342 by trapping of the sialyl-enzyme intermediate using the D59A mutant and sequencing of the purified peptic peptide. The role of D59 as the acid/base catalyst is confirmed by chemical rescue studies in which activity is restored to the D59A mutant by azide and a sialyl azide product is formed.
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Affiliation(s)
- Iben Damager
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T1Z1 Canada
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Mochalova LV, Korchagina EY, Kurova VS, Shtyria JA, Gambaryan AS, Bovin NV. Fluorescent assay for studying the substrate specificity of neuraminidase. Anal Biochem 2006; 341:190-3. [PMID: 15866544 DOI: 10.1016/j.ab.2005.02.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2004] [Indexed: 02/07/2023]
Affiliation(s)
- L V Mochalova
- Shemyakin & Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, 117997 Moscow, Russia
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Achyuthan KE, Achyuthan AM. Comparative enzymology, biochemistry and pathophysiology of human exo-alpha-sialidases (neuraminidases). Comp Biochem Physiol B Biochem Mol Biol 2001; 129:29-64. [PMID: 11337249 DOI: 10.1016/s1096-4959(01)00372-4] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This review summarizes the current research on human exo-alpha-sialidase (sialidase, neuraminidase). Where appropriate, the properties of viral, bacterial, and human sialidases have been compared. Sialic acids are implicated in diverse physiological processes. Sialidases, as enzymes acting upon sialic acids, assume importance as well. Sialidases hydrolyze the terminal, non-reducing, sialic acid linkage in glycoproteins, glycolipids, gangliosides, polysaccharides, and synthetic molecules. Therefore, a variety of assays are available to measure sialidase activity. Human sialidase is present in several organs and cells. Its cellular distribution could be cytosolic, lysosomal, or in the membrane. Human sialidase occurs in a high molecular-mass complex with several other proteins, including cathepsin A and beta-galactosidase. Multi-protein complexation is important for the in vivo integrity and catalytic activity of the sialidase. However, multi-protein complexation, the occurrence of isoenzymes, diverse subcellular localization, thermal instability, and membrane association have all contributed to difficulties in purifying and characterizing human sialidases. Human sialidase isoenzymes have recently been cloned and sequenced. Even though crystal structures for the human sialidases are not available, the highly conserved regions of the sialidase from various organisms have facilitated molecular modeling of the human enzyme and raise interesting evolutionary questions. While the molecular mechanisms vary, genetic defects leading to human sialidase deficiency are closely associated with at least two well-known human diseases, namely sialidosis and galactosialidosis. No therapy is currently available for either disease. A thorough investigation of human sialidases is therefore crucial to human health.
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Affiliation(s)
- K E Achyuthan
- ZymeTx Inc., 800 Research Parkway # 100, Oklahoma City, OK 73104, USA.
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Affiliation(s)
- G J Boons
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602
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Räbinä J, Pikkarainen M, Miyasaka M, Renkonen R. A time-resolved immunofluorometric assay of sialyl Lewis x-degrading alpha 2,3-sialidase activity. Anal Biochem 1998; 258:362-8. [PMID: 9570852 DOI: 10.1006/abio.1998.2590] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have developed an assay for alpha 2,3-sialidase (EC 3.2.1.18) which employs a biotinylated carbohydrate-polyacrylamide conjugate as substrate for the enzyme. The solution-phase sialidase reactions are followed by a selective capture of biotinylated neoglycoconjugates onto a microtitration plate coated with streptavidin. The amount of the reaction product formed is then rapidly and easily quantified using a product-specific primary antibody and europium chelate-labeled secondary antibody. This method combines the advantages of solution-phase enzymatic reaction and suitability for high-throughput screening typical of solid-phase assays. The assay gives a detectable signal with 0.4% of substrate sites desialylated. We have demonstrated the utility of the assay by measuring alpha 2,3-sialidase activity from crude lysates of cultured rat endothelial cells by using biotinylated sialyl Lewis x glycoconjugate as substrate. Endothelial sialidase(s) showed up to 250-fold higher activity toward soluble compared to immobilized substrate. Product formation detected with an anti-Lewis x antibody was linear in the range of 0.1-4 micrograms/ml of protein in endothelial cell lysate. High sensitivity of the assay was achieved by using solution-phase enzyme reaction and time-resolved fluorometric detection. The same assay format used here is easily adapted to detect activities of several different glycosidases or glycosyl-transferases by using appropriate substrates and antibodies.
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Affiliation(s)
- J Räbinä
- Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Finland
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