Alzheimer's disease is the most common cause of dementia, currently afflicting almost 40 million patients worldwide. According to the amyloid cascade hypothesis, the pathogenesis of the disease could be slowed down or even stopped by the inhibition of beta-secretase, making this aspartic acid protease a potentially important drug target site. Capillary electrophoresis is a promising technique for screening putative enzyme inhibitors due to highly effective separations, minuscule sample and other chemicals consumption, compatibility with a variety of detection techniques, and high throughput via automation. This chapter presents a method based on capillary electrophoresis coupled to mass spectrometry detection for kinetic and inhibition assays of the beta-secretase reaction with a decapeptide derived from an amyloid precursor protein.

• MeSH
• Alzheimerova nemoc farmakoterapie   metabolismus   MeSH
• amyloidový prekurzorový protein beta metabolismus   MeSH
• aspartátové endopeptidasy metabolismus   MeSH
• elektroforéza kapilární metody   MeSH
• hmotnostní spektrometrie metody   MeSH
• inhibitory enzymů farmakologie   MeSH
• inhibitory proteas farmakologie   MeSH
• kinetika MeSH
• lidé MeSH
• plošný screening metody   MeSH
• sekretasy antagonisté a inhibitory   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Capillary electrophoresis integrated immobilized enzyme reactors are becoming an increasingly popular alternative for enzyme kinetic and inhibition assays thanks to their unique set of features including cost effectiveness, repeated use of the enzyme, minuscule sample consumption, rapid analysis time and easy automation. In this work we present the development and application of a capillary electrophoresis integrated immobilized enzyme reactor based on magnetic particles for kinetic and inhibition studies of β-secretase, a key enzyme in the development of Alzheimer's disease and a promising drug target. We document the optimization of the immobilization procedure, characterization of immobilized β-secretase, optimization of a mutually compatible incubation protocol and separation method as well as the production of the capillary electrophoresis integrated immobilized enzyme reactor. The applicability of the capillary electrophoresis integrated immobilized enzyme reactor was demonstrated by kinetic assay with an unlabelled substrate and by inhibition assays using three structurally different reference inhibitors. The resulting kinetic and inhibition parameters clearly support the applicability of the herein presented method as well as document the fundamental phenomena which need to be taken in account when comparing the results to other methods.

• MeSH
• Alzheimerova nemoc farmakoterapie   metabolismus   MeSH
• bioreaktory * MeSH
• elektroforéza kapilární MeSH
• enzymy imobilizované antagonisté a inhibitory   chemie   metabolismus   MeSH
• HEK293 buňky MeSH
• inhibitory enzymů chemie   farmakologie   MeSH
• kinetika MeSH
• lidé MeSH
• peptidy chemie   farmakologie   MeSH
• sekretasy antagonisté a inhibitory   chemie   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Enzymes play an essential role in many aspects of pharmaceutical research as drug targets, drug metabolizers, enzyme drugs and more. In this specific field, enzyme assays are required to meet a number of specific requirements, such as low cost, easy automation, and high reliability. The integration of an immobilized-enzyme reactor to capillary electrophoresis represents a unique approach to fulfilling these criteria by combining the benefits of enzyme immobilization, that is, increased stability and repeated use, as well as the minute sample consumption, short analysis time, and efficient analysis provided by capillary electrophoresis. In this review, we summarize, analyze, and discuss published works where pharmaceutically relevant enzymes were used to prepare capillary electrophoresis-integrated immobilized-enzyme reactors in an online manner. The presented assays are divided into three distinct groups based on the drug-enzyme relationship. The first, more extensively studied group employs enzymes that are considered to be therapeutic targets, the second group of assays present tools to assess drug metabolism and the third group assesses enzyme drugs. Furthermore, we examine various methods of enzyme immobilization and their implications for assay properties.

• MeSH
• design vybavení MeSH
• elektroforéza kapilární * MeSH
• enzymatické testy MeSH
• enzymy imobilizované chemie   MeSH
• farmaceutický výzkum MeSH
• genom lidský MeSH
• kinetika MeSH
• léčivé přípravky MeSH
• lidé MeSH
• magnetismus MeSH
• proteomika MeSH
• reprodukovatelnost výsledků MeSH
• statická elektřina MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) is a well-established method with a unique set of qualities including sensitivity, minute sample consumption, and label-free detection, all of which are highly desired in enzyme assays. On the other hand, the application of MALDI TOF MS is usually limited by high concentrations of MS-incompatible compounds in the reaction mixture such as salts or organic solvents. Here, we introduce kinetic and inhibition studies of β-secretase (BACE1), a key enzyme of the progression of Alzheimer's disease. Compatibility of the enzyme assay with MALDI TOF MS was achieved, providing both a complex protocol including a desalting step designed for rigorous kinetic studies and a simple mix-and-measure protocol designed for high-throughput inhibitor screening. In comparison with fluorescent or colorimetric assays, MALDI TOF MS represents a sensitive, fast, and label-free technique with minimal sample preparation. In contrast to other MS-based methodological approaches typically used in drug discovery processes, such as a direct injection MS or MS-coupled liquid chromatography or capillary electrophoresis, MALDI TOF MS enables direct analysis and is a highly suitable approach for high-throughput screening. The method's applicability is strongly supported by the high correlation of the acquired kinetic and inhibition parameters with data from the literature as well as from our previous research. Graphical abstract ᅟ.

• MeSH
• Alzheimerova nemoc enzymologie   MeSH
• aminokyseliny antagonisté a inhibitory   MeSH
• HEK293 buňky MeSH
• heterocyklické sloučeniny bicyklické farmakologie   MeSH
• kinetika MeSH
• kyseliny pikolinové farmakologie   MeSH
• lidé MeSH
• preklinické hodnocení léčiv metody   MeSH
• pyrimidinony farmakologie   MeSH
• sekretasy antagonisté a inhibitory   metabolismus   MeSH
• spektrometrie hmotnostní - ionizace laserem za účasti matrice metody   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

In this paper, we demonstrate the effectiveness of a new 3D printed magnet holder that enables capture of magnetic microparticles in commercially available capillary electrophoresis equipment with a liquid or air based coolant system. The design as well as the method to capture magnetic microparticles inside the capillary are discussed. This setup was tested at temperature and pH values suitable for performing enzymatic reactions. To demonstrate its applicability in CE- immobilized microenzyme reactors (IMER) development, human flavin-containing monooxygenase 3 and bovine serum albumin were immobilized on amino functionalized magnetic microparticles using glutaraldehyde. These microparticles were subsequently used to perform in-line capillary electrophoresis with clozapine as a model substrate. This setup could be used further to establish CE-IMERs of other drug metabolic enzymes in a commercially available liquid based capillary coolant system. The CE-IMER setup was successful, although a subsequent decrease in enzyme activity was observed on repeated runs.

• MeSH
• aminy chemie   MeSH
• design vybavení přístrojové vybavení   MeSH
• elektroforéza kapilární přístrojové vybavení   MeSH
• enzymy imobilizované chemie   MeSH
• glutaraldehyd chemie   MeSH
• klozapin chemie   MeSH
• lidé MeSH
• magnetické pole MeSH
• magnety chemie   MeSH
• mikrosféry * MeSH
• NADP chemie   MeSH
• oxid křemičitý chemie   MeSH
• oxygenasy chemie   MeSH
• povrchové vlastnosti MeSH
• sérový albumin hovězí chemie   MeSH
• stabilita enzymů MeSH
• teplota MeSH
• velikost částic MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Alzheimer's disease is the most common cause of dementia, afflicting over 34 million patients worldwide. Since β-secretase is a rate-limiting enzyme of the production of neurotoxic β-amyloid peptide oligomers abnormally accumulated in the affected brain tissue, its specific inhibition appears to be a promising approach to slowing down or even stopping the progression of the disease. Hence two on-line capillary electrophoretic methods for studies of β-secretase activity based on the principles of transverse diffusion of laminar flow profiles and electrophoretically mediated microanalysis were developed, both using a simple unlabeled peptide substrate and UV detection. The optimized procedures were thoroughly validated and applied for determining the enzyme's kinetic parameters and the inhibition characteristics of two potent probe inhibitors. The resulting values were found to be comparable to literature data obtained with other analytical techniques. The suitability of the employed methodologies for different experimental designs is discussed on the basis of a statistical evaluation of the experimental data. The presented methods constitute a miniaturized and fully automated tool, which should be suitable for kinetic and inhibition studies of β-secretase as a target for Alzheimer's disease drug discovery in the early stages of the development of a new drug.

• MeSH
• aktivace enzymů účinky léků   MeSH
• Alzheimerova nemoc enzymologie   MeSH
• elektroforéza kapilární normy   MeSH
• enzymatické testy přístrojové vybavení   metody   MeSH
• inhibitory enzymů farmakologie   MeSH
• kinetika MeSH
• lidé MeSH
• objevování léků * MeSH
• sekretasy antagonisté a inhibitory   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH

In this work a novel capillary electrophoresis-mass spectrometry (CE-MS) based method was developed and validated for the assay of β-secretase (BACE1) activity as a potential target for Alzheimer's disease (AD) treatment. In contrast with the typically used Förster resonance energy transfer (FRET) assays, an unlabelled decapeptide derived from the amyloid precursor protein BACE1 site with the "Swedish mutation" was used as the substrate. The CE usage enabled the enzymatic reaction to be carried out in as small a volume as 100μL in 60min with sufficient yields of proteolytic product, which was subsequently separated in a bare fused silica capillary using 12.5% acetic acid as a background electrolyte and detected by MS. The limits of detection and quantitation were estimated using the signal to noise ratio to be 5nM (S/N=3) and 15nM (S/N=10), respectively, both being well below the working range for kinetic and inhibition studies. Its applicability for the kinetic study of BACE1 was demonstrated using optimized enzyme assay conditions and the estimated kinetic parameter values were confirmed by classic CE-UV analyses. The method was finally used for the main purpose for which it was developed - to screen BACE1 inhibitors as potential AD therapeutics. The resulting kinetic and inhibition parameters values were compared to those published in the literature, which were almost exclusively obtained by FRET based assays. These comparisons brought up several issues that are further discussed below and favour the application of an unlabelled substrate. The proposed CE-MS based method offers a high-throughput capability for new drug development.

• MeSH
• Alzheimerova nemoc farmakoterapie   MeSH
• aspartátové endopeptidasy antagonisté a inhibitory   MeSH
• elektroforéza kapilární metody   MeSH
• HEK293 buňky MeSH
• hmotnostní spektrometrie metody   MeSH
• inhibitory proteas analýza   terapeutické užití   MeSH
• kinetika MeSH
• lidé MeSH
• preklinické hodnocení léčiv metody   MeSH
• sekretasy antagonisté a inhibitory   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• validační studie MeSH

In this work, the combination of an immobilized enzyme microreactor (IMER) based on the clinically important isoform cytochrome P450 2C9 (CYP2C9) with capillary electrophoresis (CE) is presented. The CYP2C9 was attached to magnetic SiMAG-carboxyl microparticles using the carbodiimide method. The formation of an IMER in the inlet part of the separation capillary was ensured by two permanent magnets fixed in a cassette from the CE apparatus in the repulsive arrangement. The resulting on-line system provides an integration of enzyme reaction mixing and incubation, reaction products separation, detection and quantification into a single fully automated procedure with the possibility of repetitive use of the enzyme and minuscule amounts of reactant consumption. The on-line kinetic and inhibition studies of CYP2C9's reaction with diclofenac as a model substrate and sulfaphenazole as a model inhibitor were conducted in order to demonstrate its practical applicability. Values of the apparent Michalis-Menten constant, apparent maximum reaction velocity, Hill coefficient, apparent inhibition constant and half-maximal inhibition concentration were determined on the basis of the calculation of the effective substrate and inhibitor concentrations inside the capillary IMER using a model described by the Hagen-Poisseulle law and a novel enhanced model that reflects the influence of the reactants' diffusion during the injection process.

• MeSH
• bioreaktory MeSH
• difuze MeSH
• diklofenak chemie   MeSH
• elektroforéza kapilární * MeSH
• enzymy imobilizované metabolismus   MeSH
• kinetika MeSH
• objevování léků přístrojové vybavení   metody   MeSH
• systém (enzymů) cytochromů P-450 chemie   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH