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Jin SB, Kim HA, Shin JA, Jung NH, Park SY, Hong S, Kong KH. Recombinant expression and tryptophan-assisted analysis of human sweet taste receptor T1R3's extracellular domain in sweetener interaction studies. Prep Biochem Biotechnol 2024:1-8. [PMID: 38578840 DOI: 10.1080/10826068.2024.2336985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2024]
Abstract
The human palate can discern multiple tastes; however, it predominantly perceives five fundamental flavors: sweetness, saltiness, sourness, bitterness, and umami. Sweetness is primarily mediated through the sweet taste receptor, a membrane-bound heterodimeric structure comprising T1R2-T1R3. However, unraveling the structural and mechanistic intricacies of the sweet taste receptor has proven challenging. This study aimed to address this knowledge gap by expressing an extracellular N-terminal domain encompassing the cysteine-rich domain of human hT1R3 (hT1R3-TMD) in Escherichia coli. The expressed protein was obtained as inclusion bodies, purified by metal affinity chromatography, and refolded using the dilution-refolding method. Through rigorous analysis, we confirmed the successful refolding of hT1R3-TMD and elucidated its structural characteristics using circular dichroism spectroscopy. Notably, the refolded protein was found to exist as either a monomer or a dimer, depending on its concentration. A tryptophan fluorescence quenching assay revealed that the dissociation constants for sucrose, sucralose, and brazzein were >9500 μM, 2380 μM and 14.3 μM, respectively. Our findings highlight the utility of this E. coli expression system for producing functional hT1R3-TMD for investigations and demonstrate the efficacy of the tryptophan fluorescence quenching assay in revealing complex interactions between sweet taste receptors and various sweeteners.
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Affiliation(s)
- Soo-Bin Jin
- Department of Chemistry, College of Natural Sciences, Chung-Ang University, Seoul, Korea
| | - Hyun-A Kim
- Department of Chemistry, College of Natural Sciences, Chung-Ang University, Seoul, Korea
| | - Ji-Ae Shin
- Department of Chemistry, College of Natural Sciences, Chung-Ang University, Seoul, Korea
| | - Na-Hee Jung
- Department of Chemistry, College of Natural Sciences, Chung-Ang University, Seoul, Korea
| | - Seo-Young Park
- Department of Chemistry, College of Natural Sciences, Chung-Ang University, Seoul, Korea
| | - Sungguan Hong
- Department of Chemistry, College of Natural Sciences, Chung-Ang University, Seoul, Korea
| | - Kwang-Hoon Kong
- Department of Chemistry, College of Natural Sciences, Chung-Ang University, Seoul, Korea
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Jin SB, Jang SW, Shin JA, Jung NH, Kim HA, Park SY, Lee WC, Kong KH. Functional significance of serine 13 in the active site of glutathione S-transferase F3 from Oryza sativa. Pestic Biochem Physiol 2023; 194:105463. [PMID: 37532308 DOI: 10.1016/j.pestbp.2023.105463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 05/09/2023] [Accepted: 05/09/2023] [Indexed: 08/04/2023]
Abstract
Plant glutathione S-transferase (GST, EC 2.5.1.18) is an enzyme that detoxifies various electrophilic compounds including herbicides and organic pollutants by catalyzing the formation of conjugates with reduced glutathione (GSH). Although the structure and function of the GST subunits in rice, an important food in Asia, are not well understood, they are crucial for herbicide development. To investigate the role of active site residues in rice Phi-class GSTF3 (OsGSTF3), evolutionarily conserved serine residues were replaced with alanine using site-directed mutagenesis to obtain the mutants S13A, S38A, S69A, and S169A. These four mutants were expressed in Escherichia coli and purified to electrophoretic homogeneity using immobilized GSH affinity chromatography. Mutation of Ser13 to Ala resulted in substantial reductions in specific activities and kcat/Km values for the GSH-[1-chloro-2,4-dinitrobenzene (CDNB)] conjugation reaction. In contrast, mutations of Ser38, Ser69, and Ser169 to Ala had little effect on the activities and kinetic parameters. Additionally, the mutation of Ser13 to Ala significantly affected the KmGSH and I50 values of S-hexylglutathione and S-(2,4-dinitrophenyl)glutathione, which compete with GSH and the product of GSH-CDNB conjugation, respectively. A pH-log (kcat/KmCDNB) plot was used to estimate the pKa value of GSH in the enzyme-GSH complex of the wild-type enzyme, which was approximately 6.9. However, the pKa value of GSH in the enzyme-GSH complex of the S13A mutant was approximately 8.7, which was about 1.8 pK units higher than that of the wild-type enzyme. OsGSTF3 was also crystallized for crystallographic study, and the structure analyses revealed that Ser13 is located in the active site and that its side chain is in close proximity to the thiol group of glutathione bound in the enzyme. Based on these substitution effects on kinetic parameters, the dependence of kinetic parameters on the pH and 3-dimensional structure, it was suggested that Ser13 in rice OsGSTF3 is the residue responsible for catalytic activity by lowering the pKa of GSH in the enzyme-GSH complex and enhancing the nucleophilicity of the GSH thiol in the active site.
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Affiliation(s)
- Su-Bin Jin
- Biomolecular Chemistry Laboratory, Department of Chemistry, College of Natural Sciences, Chung-Ang University, 84, Huksuk-Ro, Dongjak-Gu, Seoul 06974, Republic of Korea
| | - Si-Wook Jang
- Biomolecular Chemistry Laboratory, Department of Chemistry, College of Natural Sciences, Chung-Ang University, 84, Huksuk-Ro, Dongjak-Gu, Seoul 06974, Republic of Korea
| | - Ji-Ae Shin
- Biomolecular Chemistry Laboratory, Department of Chemistry, College of Natural Sciences, Chung-Ang University, 84, Huksuk-Ro, Dongjak-Gu, Seoul 06974, Republic of Korea
| | - Na-Hee Jung
- Biomolecular Chemistry Laboratory, Department of Chemistry, College of Natural Sciences, Chung-Ang University, 84, Huksuk-Ro, Dongjak-Gu, Seoul 06974, Republic of Korea
| | - Hyun-A Kim
- Biomolecular Chemistry Laboratory, Department of Chemistry, College of Natural Sciences, Chung-Ang University, 84, Huksuk-Ro, Dongjak-Gu, Seoul 06974, Republic of Korea
| | - Seo-Young Park
- Biomolecular Chemistry Laboratory, Department of Chemistry, College of Natural Sciences, Chung-Ang University, 84, Huksuk-Ro, Dongjak-Gu, Seoul 06974, Republic of Korea
| | - Woo-Cheol Lee
- Biomolecular Chemistry Laboratory, Department of Chemistry, College of Natural Sciences, Chung-Ang University, 84, Huksuk-Ro, Dongjak-Gu, Seoul 06974, Republic of Korea.
| | - Kwang-Hoon Kong
- Biomolecular Chemistry Laboratory, Department of Chemistry, College of Natural Sciences, Chung-Ang University, 84, Huksuk-Ro, Dongjak-Gu, Seoul 06974, Republic of Korea.
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Jung NH, Münchau A, Mall V. [Neuronal plasticity and neuromodulation in pediatric neurology]. Nervenarzt 2018; 89:1131-1139. [PMID: 30141068 DOI: 10.1007/s00115-018-0586-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
BACKGROUND Neuronal plasticity is a core mechanism for learning and memory. Abnormal neuronal plasticity has emerged as a key mechanism in many neurological and neuropediatric diseases. OBJECTIVE Chances and perspectives of neuromodulation techniques in neurological and neuropediatric diseases with altered neuronal plasticity. MATERIAL AND METHODS Presentation and discussion of own results of neuronal plasticity investigations in patients with neurodevelopmental disorders including RASopathies, autism spectrum disorders (ASD) and Gilles de la Tourette syndrome (GTS). RESULTS The results of neuronal plasticity studies in patients with RASopathies, ASD and GTS underline the pathophysiological relevance of abnormal neuronal plasticity in these diseases. Transcranial magnetic stimulation (TMS) is a useful tool to examine and also induce neuronal plasticity in these patients. CONCLUSION Neuronal plasticity appears to be an important pathophysiological factor in neuronal developmental disorders and can be investigated using TMS. New and innovative techniques may offer novel approaches for individualized TMS applications, particularly in children with neuropediatric conditions.
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Affiliation(s)
- N H Jung
- Fakultät für Medizin, Lehrstuhl für Sozialpädiatrie, Technische Universität München, Heiglhoftstr. 65, 81377, München, Deutschland.
| | - A Münchau
- Institut für Neurogenetik, Universität zu Lübeck, Marie-Curie-Straße, 23562, Lübeck, Deutschland
| | - V Mall
- Fakultät für Medizin, Lehrstuhl für Sozialpädiatrie, Technische Universität München, Heiglhoftstr. 65, 81377, München, Deutschland
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Jung NH, Gleich B, Siebner HR, Kalb A, Gattinger N, Mall V. Induktion neuronaler Plastizität durch biphasische transkranielle Magnetstimulation (TMS) mittels Quattropulsen mit einfacher und doppelter Sinusvollwelle. KLIN NEUROPHYSIOL 2014. [DOI: 10.1055/s-0034-1371276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Jung NH, Heinen F, Westhoff B, Doederlein L, Reissig A, Berweck S, Linder-Lucht M, Schandelmaier S, Mall V. Hip lateralisation in children with bilateral spastic cerebral palsy treated with botulinum toxin type A: a 2-year follow-up. Neuropediatrics 2011; 42:18-23. [PMID: 21500143 DOI: 10.1055/s-0031-1275344] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We investigated the effect of BoNT/A injection on hip lateralisation in children with bilateral spastic cerebral palsy and bilateral adductor spasticity. Pelvic radiographs using Reimers' migration index (MI) were evaluated from 27 children (n=9 females, n=18 males; mean age 5.2 ± 1.96 years; range: 2-10 years; initial MI <50%) with bilateral spastic cerebral palsy over a time period of 2 years. All received injections of BoNT/A (Dysport) every 12 weeks with a dose of 30 Units per kilogram body weight into adductor and medial hamstring muscles on both sides. The MI was calculated before treatment and after 1 and 2 years. The mean MI increased from 25.5% (range: 0-48) to 26.7% (+1.2%, range: 0-79) on the right side and from 28.0% (range: 0-40) to 30.6% (+2.6%, range: 3-84) on the left side over 2 years, respectively. Hips of one patient dislocated bilaterally. The mean MI remained stable over 2 years. Although a specific BoNT/A effect cannot be proven because of the open design of this study, we provide strong evidence that the MI can be kept stable for a time period of 2 years under non-surgical management including therapy with BoNT/A even in CP patients with a high risk for hip dislocation.
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Affiliation(s)
- N H Jung
- Division of Neuropediatrics and Muscular Disorders, Department of Pediatrics and Adolescent Medicine, University Hospital Freiburg, Freiburg, Germany
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