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Hecko S, Schiefer A, Badenhorst CPS, Fink MJ, Mihovilovic MD, Bornscheuer UT, Rudroff F. Enlightening the Path to Protein Engineering: Chemoselective Turn-On Probes for High-Throughput Screening of Enzymatic Activity. Chem Rev 2023; 123:2832-2901. [PMID: 36853077 PMCID: PMC10037340 DOI: 10.1021/acs.chemrev.2c00304] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
Many successful stories in enzyme engineering are based on the creation of randomized diversity in large mutant libraries, containing millions to billions of enzyme variants. Methods that enabled their evaluation with high throughput are dominated by spectroscopic techniques due to their high speed and sensitivity. A large proportion of studies relies on fluorogenic substrates that mimic the chemical properties of the target or coupled enzymatic assays with an optical read-out that assesses the desired catalytic efficiency indirectly. The most reliable hits, however, are achieved by screening for conversions of the starting material to the desired product. For this purpose, functional group assays offer a general approach to achieve a fast, optical read-out. They use the chemoselectivity, differences in electronic and steric properties of various functional groups, to reduce the number of false-positive results and the analytical noise stemming from enzymatic background activities. This review summarizes the developments and use of functional group probes for chemoselective derivatizations, with a clear focus on screening for enzymatic activity in protein engineering.
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Affiliation(s)
- Sebastian Hecko
- Institute of Applied Synthetic Chemistry, OC-163, TU Wien, Getreidemarkt 9, 1060 Vienna, Austria
| | - Astrid Schiefer
- Institute of Applied Synthetic Chemistry, OC-163, TU Wien, Getreidemarkt 9, 1060 Vienna, Austria
| | - Christoffel P S Badenhorst
- Institute of Biochemistry, Dept. of Biotechnology & Enzyme Catalysis, University of Greifswald, Felix-Hausdorff-Str. 4, 17489 Greifswald, Germany
| | - Michael J Fink
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St, Cambridge, Massachusetts 02138, United States
| | - Marko D Mihovilovic
- Institute of Applied Synthetic Chemistry, OC-163, TU Wien, Getreidemarkt 9, 1060 Vienna, Austria
| | - Uwe T Bornscheuer
- Institute of Biochemistry, Dept. of Biotechnology & Enzyme Catalysis, University of Greifswald, Felix-Hausdorff-Str. 4, 17489 Greifswald, Germany
| | - Florian Rudroff
- Institute of Applied Synthetic Chemistry, OC-163, TU Wien, Getreidemarkt 9, 1060 Vienna, Austria
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Maddukuri N, Zhang Q, Zhang N, Gong M. Rapid labeling of amino acid neurotransmitters with a fluorescent thiol in the presence of o-phthalaldehyde. Electrophoresis 2017; 38:507-512. [PMID: 27747885 PMCID: PMC5321804 DOI: 10.1002/elps.201600374] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 09/09/2016] [Accepted: 10/05/2016] [Indexed: 12/20/2022]
Abstract
LIF detection often requires labeling of analytes with fluorophores; and fast fluorescent derivatization is valuable for high-throughput analysis with flow-gated CE. Here, we report a fast fluorescein-labeling scheme for amino acid neurotransmitters, which were then rapidly separated and detected in flow-gated CE. This scheme was based on the reaction between primary amines and o-phthalaldehyde in the presence of a fluorescent thiol, 2-((5-fluoresceinyl)aminocarbonyl)ethyl mercaptan (FACE-SH). The short reaction time (<30 s) was suited for on-line mixing and derivatization that was directly coupled with flow-gated CE for rapid electrophoretic separation and sensitive LIF detection. To maintain the effective concentration of reactive FACE-SH, Tris(2-carboxyethyl)phosphine was added to the derivatization reagents to prevent thiol loss due to oxidation. This labeling scheme was applied to the detection of neurotransmitters by coupling in vitro microdialysis with online derivatization and flow-gated CE. It is also anticipated that this fluorophore tagging scheme would be valuable for on-chip labeling of proteins retained on support in SPE.
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Affiliation(s)
- Naveen Maddukuri
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260, United States
| | - Qiyang Zhang
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260, United States
| | - Ning Zhang
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260, United States
| | - Maojun Gong
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260, United States
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Cifuentes Castro VH, López Valenzuela CL, Salazar Sánchez JC, Peña KP, López Pérez SJ, Ibarra JO, Villagrán AM. An update of the classical and novel methods used for measuring fast neurotransmitters during normal and brain altered function. Curr Neuropharmacol 2014; 12:490-508. [PMID: 25977677 PMCID: PMC4428024 DOI: 10.2174/1570159x13666141223223657] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 11/22/2014] [Accepted: 12/19/2014] [Indexed: 11/22/2022] Open
Abstract
To understand better the cerebral functions, several methods have been developed to study the brain activity, they could be related with morphological, electrophysiological, molecular and neurochemical techniques. Monitoring neurotransmitter concentration is a key role to know better how the brain works during normal or pathological conditions, as well as for studying the changes in neurotransmitter concentration with the use of several drugs that could affect or reestablish the normal brain activity. Immediate response of the brain to environmental conditions is related with the release of the fast acting neurotransmission by glutamate (Glu), γ-aminobutyric acid (GABA) and acetylcholine (ACh) through the opening of ligand-operated ion channels. Neurotransmitter release is mainly determined by the classical microdialysis technique, this is generally coupled to high performance liquid chromatography (HPLC). Detection of neurotransmitters can be done by fluorescence, optical density, electrochemistry or other detection systems more sophisticated. Although the microdialysis method is the golden technique to monitor the brain neurotransmitters, it has a poor temporal resolution. Recently, with the use of biosensor the drawback of temporal resolution has been improved considerably, however other inconveniences have merged, such as stability, reproducibility and the lack of reliable biosensors mainly for GABA. The aim of this review is to show the important advances in the different ways to measure neurotransmitter concentrations; both with the use of classic techniques as well as with the novel methods and alternant approaches to improve the temporal resolution.
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Affiliation(s)
| | | | | | | | | | | | - Alberto Morales Villagrán
- Department of Molecular and Cellular Biology, Camino Ramón Padilla Sánchez 2100, Nextipac, Zapopan,
Jalisco, México, Zip code: 45110, Mexico
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Rauf F, Huang Y, Muhandiramlage TP, Aspinwall CA. Analysis of protein kinase A activity in insulin-secreting cells using a cell-penetrating protein substrate and capillary electrophoresis. Anal Bioanal Chem 2010; 397:3359-67. [PMID: 20458471 PMCID: PMC3064950 DOI: 10.1007/s00216-010-3776-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2010] [Revised: 04/19/2010] [Accepted: 04/22/2010] [Indexed: 10/19/2022]
Abstract
A cell-penetrating, fluorescent protein substrate was developed to monitor intracellular protein kinase A (PKA) activity in cells without the need for cellular transfection. The PKA substrate (PKAS) was prepared with a 6xhistidine purification tag, an enhanced green fluorescent protein (EGFP) reporter, an HIV-TAT protein transduction domain for cellular translocation and a pentaphosphorylation motif specific for PKA. PKAS was expressed in Escherichia coli and purified by metal affinity chromatography. Incubation of PKAS in the extracellular media facilitated translocation into the intracellular milieu in HeLa cells, betaTC-3 cells and pancreatic islets with minimal toxicity in a time and concentration dependent manner. Upon cellular loading, glucose-dependent phosphorylation of PKAS was observed in both betaTC-3 cells and pancreatic islets via capillary zone electrophoresis. In pancreatic islets, maximal PKAS phosphorylation (83 +/- 6%) was observed at 12 mM glucose, whereas maximal PKAS phosphorylation (86 +/- 4%) in betaTC-3 cells was observed at 3 mM glucose indicating a left-shifted glucose sensitivity. Increased PKAS phosphorylation was observed in the presence of PKA stimulators forskolin and 8-Br-cAMP (33% and 16%, respectively), with corresponding decreases in PKAS phosphorylation observed in the presence of PKA inhibitors staurosporine and H-89 (40% and 54%, respectively).
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Affiliation(s)
- Femina Rauf
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Yiding Huang
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | | | - Craig A. Aspinwall
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
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Guihen E, O'Connor WT. Capillary and microchip electrophoresis in microdialysis: recent applications. Electrophoresis 2010; 31:55-64. [PMID: 20039293 DOI: 10.1002/elps.200900467] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The theme of this review is to highlight the importance of microscale electrophoretic-based separation systems in microdialysis (microD). The ability of CE and MCE to yield very rapid and highly efficient separations using just nanolitre volumes of microdialysate samples will also be discussed. Recent advances in this area will be highlighted, by illustration of some exciting new applications while the need for further innovation will be covered. The first section briefly introduces the concept of microD sampling coupled with electrophoresis-based separation and the inherent advantages of this approach. The following section highlights some specific applications of CE separations in the detection of important biomarkers such as low-molecular-weight neurotransmitters, amino acids, and other molecules that are frequently encountered in microD. Various detection modes in CE are outlined and some of the advantages and drawbacks thereof are discussed. The last section introduces the concepts of micro-total analysis systems and the coupling of MCE and microD. Some of the latest innovations will be illustrated. The concluding section reflects on the future of this important chemical alliance between microD and CE/MCE.
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Affiliation(s)
- Elizabeth Guihen
- Graduate Entry Medical School and Materials and Surface Science Institute, University of Limerick, Limerick, Ireland.
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Perry M, Li Q, Kennedy RT. Review of recent advances in analytical techniques for the determination of neurotransmitters. Anal Chim Acta 2009; 653:1-22. [PMID: 19800472 PMCID: PMC2759352 DOI: 10.1016/j.aca.2009.08.038] [Citation(s) in RCA: 248] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Revised: 08/25/2009] [Accepted: 08/27/2009] [Indexed: 12/18/2022]
Abstract
Methods and advances for monitoring neurotransmitters in vivo or for tissue analysis of neurotransmitters over the last five years are reviewed. The review is organized primarily by neurotransmitter type. Transmitter and related compounds may be monitored by either in vivo sampling coupled to analytical methods or implanted sensors. Sampling is primarily performed using microdialysis, but low-flow push-pull perfusion may offer advantages of spatial resolution while minimizing the tissue disruption associated with higher flow rates. Analytical techniques coupled to these sampling methods include liquid chromatography, capillary electrophoresis, enzyme assays, sensors, and mass spectrometry. Methods for the detection of amino acid, monoamine, neuropeptide, acetylcholine, nucleoside, and soluble gas neurotransmitters have been developed and improved upon. Advances in the speed and sensitivity of these methods have enabled improvements in temporal resolution and increased the number of compounds detectable. Similar advances have enabled improved detection at tissue samples, with a substantial emphasis on single cell and other small samples. Sensors provide excellent temporal and spatial resolution for in vivo monitoring. Advances in application to catecholamines, indoleamines, and amino acids have been prominent. Improvements in stability, sensitivity, and selectivity of the sensors have been of paramount interest.
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Affiliation(s)
- Maura Perry
- University of Michigan, Department of Chemistry, 930 N. University, Ann Arbor, MI 48109-1055, USA
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Ciriacks Klinker C, Bowser MT. 4-Fluoro-7-nitro-2,1,3-benzoxadiazole as a Fluorogenic Labeling Reagent for the in Vivo Analysis of Amino Acid Neurotransmitters Using Online Microdialysis−Capillary Electrophoresis. Anal Chem 2007; 79:8747-54. [DOI: 10.1021/ac071433o] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Chanda Ciriacks Klinker
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455
| | - Michael T. Bowser
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455
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