Recent developments in CE and CEC of peptides

Recent developments in capillary and microchip electroseparations of peptides (2021-mid-2023)

This review article brings a comprehensive survey of developments and applications of high-performance capillary and microchip electromigration methods (zone electrophoresis in a free solution or in sieving media, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography, and electrochromatography) for analysis, micropreparation, and physicochemical characterization of peptides in the period from 2021 up to ca. the middle of 2023. Progress in the study of electromigration properties of peptides and various aspects of their analysis, such as sample preparation, adsorption suppression, electroosmotic flow regulation, and detection, are presented. New developments in the particular capillary electromigration methods are demonstrated, and several types of their applications are reported. They cover qualitative and quantitative analysis of synthetic or isolated peptides and determination of peptides in complex biomatrices, peptide profiling of biofluids and tissues, and monitoring of chemical and enzymatic reactions and physicochemical changes of peptides. They include also amino acid and sequence analysis of peptides, peptide mapping of proteins, separation of stereoisomers of peptides, and their chiral analyses. In addition, micropreparative separations and physicochemical characterization of peptides and their interactions with other (bio)molecules by the above CE methods are described.

Recent developments in capillary and microchip electroseparations of peptides (2019-mid 2021)

The review provides a comprehensive overview of developments and applications of high performance capillary and microchip electroseparation methods (zone electrophoresis, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography, and electrochromatography) for analysis, microscale isolation, and physicochemical characterization of peptides from 2019 up to approximately the middle of 2021. Advances in the investigation of electromigration properties of peptides and in the methodology of their analysis, such as sample preparation, sorption suppression, EOF control, and detection, are presented. New developments in the individual CE and CEC methods are demonstrated and several types of their applications are shown. They include qualitative and quantitative analysis, determination in complex biomatrices, monitoring of chemical and enzymatic reactions and physicochemical changes, amino acid, sequence, and chiral analyses, and peptide mapping of proteins. In addition, micropreparative separations and determination of significant physicochemical parameters of peptides by CE and CEC methods are described.

Recent developments in capillary and microchip electroseparations of peptides (2015-mid 2017)

The review brings a comprehensive overview of recent developments and applications of high performance capillary and microchip electroseparation methods (zone electrophoresis, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography, and electrochromatography) to analysis, microscale isolation, purification, and physicochemical and biochemical characterization of peptides in the years 2015, 2016, and ca. up to the middle of 2017. Advances in the investigation of electromigration properties of peptides and in the methodology of their analysis (sample preseparation, preconcentration and derivatization, adsorption suppression and EOF control, and detection) are described. New developments in particular CE and CEC methods are presented and several types of their applications to peptide analysis are reported: qualitative and quantitative analysis, determination in complex (bio)matrices, monitoring of chemical and enzymatical reactions and physical changes, amino acid, sequence and chiral analysis, and peptide mapping of proteins. Some micropreparative peptide separations are shown and capabilities of CE and CEC methods to provide important physicochemical characteristics of peptides are demonstrated.

Separation of Peptides by Capillary Electrophoresis

Peptides are an important class of analytes in chemistry, biochemistry, food chemistry, as well as medical and pharmaceutical sciences including biomarker analysis in peptidomics and proteomics. As a high-resolution technique, capillary electrophoresis (CE) is well suited for the analysis of polar compounds such as peptides. In addition, CE is orthogonal to high-performance liquid chromatography (HPLC) as both techniques are based on different physicochemical separation principles. For the successful development of peptide separations by CE, operational parameters including puffer pH, buffer concentration and buffer type, applied voltage, capillary dimensions, as well as background electrolyte additives such as detergents, ion-pairing reagents, cyclodextrins, (poly)amines, and soluble polymers have to be considered and optimized.

Recent developments in capillary and microchip electroseparations of peptides (2011-2013)

The review presents a comprehensive survey of recent developments and applications of capillary and microchip electroseparation methods (zone electrophoresis, ITP, IEF, affinity electrophoresis, EKC, and electrochromatography) for analysis, isolation, purification, and physicochemical and biochemical characterization of peptides. Advances in the investigation of electromigration properties of peptides, in the methodology of their analysis, including sample preseparation, preconcentration and derivatization, adsorption suppression and EOF control, as well as in detection of peptides, are presented. New developments in particular CE and CEC modes are reported and several types of their applications to peptide analysis are described: conventional qualitative and quantitative analysis, determination in complex (bio)matrices, monitoring of chemical and enzymatical reactions and physical changes, amino acid, sequence and chiral analysis, and peptide mapping of proteins. Some micropreparative peptide separations are shown and capabilities of CE and CEC techniques to provide relevant physicochemical characteristics of peptides are demonstrated.

Analysis of therapeutic peptides in human urine by combination of capillary zone electrophoresis-electrospray mass spectrometry with preparative capillary isotachophoresis sample pretreatment

The presented study deals with the off-line coupling of preparative isotachophoresis (pITP) with on-line combination of capillary zone electrophoresis with electrospray mass spectrometric detection (CZE-ESI-MS) used for the analysis of therapeutic peptides (anserine, carnosine, and buserelin) in complex matrix (urine). Preparative capillary isotachophoresis, operating in a discontinuous fractionation mode in column-coupling configuration, served as a sample pretreatment technique to separation, and fractionation of mixture of therapeutic peptides present in urine at low concentration level. The fractions isolated by pITP procedure were subsequently analyzed by capillary zone electrophoresis with electrospray mass spectrometric detection. Acetic acid at 200 mmol L(-1) concentration served as background electrolyte in CZE stage and it is compatible with MS detection in positive ionization mode. In pITP fractionation procedure, sodium cation (10 mmol L(-1) concentration) as leading ion and beta-alanine as terminating ion (20 mmol L(-1) concentration) were used. While using CZE-ESI-MS, the limits of detection were 0.18 μg mL(-1) for carnosine, 0.17 μg mL(-1) for anserine and 0.64 μg mL(-1) for buserelin in water and 0.19 μg mL(-1) for carnosine, 0.50 μg mL(-1) for anserine and 0.74 μg mL(-1) for buserelin in 10 times diluted urine, respectively. The cleaning power of pITP sample pretreatment was proved as the peptides provided the higher MS signals at lower concentration levels resulting from the minimized matrix effects. The quality of obtained MS/MS spectra was very good so that they can provide information about the structure of analytes, and they were used for verification of the analytes identities. The pITP pretreatment improved the detection limits of the analyzed therapeutic peptides at least 25 times compared to the CZE-ESI-MS itself.

Size separation of proteins by capillary zone electrophoresis with cationic hitchhiking

The paper describes a method of size separation of proteins by capillary sieving electrophoresis with cationic surfactant. Proteins are separated within 12 min with repeatability of migration times better than 0.2%. Some proteins achieve the separation efficiency of 200,000 theoretical plates. The method can be used for determination of protein relative molecular masses. The accuracy of the determined relative molecular masses and the limitation of the method were investigated by the analysis of more than 60 proteins. The method also allows separation of protein oligomers. Proteins can be quantitated after the electrokinetic injection in the concentration range 0.07-0.43 g/L. The average detection limit is about 2 mg/L.

Non-enzymatic posttranslational modifications of bovine serum albumin by oxo-compounds investigated by high-performance liquid chromatography-mass spectrometry and capillary zone electrophoresis-mass spectrometry

Non-enzymatic posttranslational modifications of bovine serum albumin (BSA) by various oxo-compounds (glucose, ribose, glyoxal and glutardialdehyde) have been investigated using high-performance liquid chromatography (HPLC) and capillary zone electrophoresis (CZE). Both of these methods used mass spectrometric (MS) detection. Three enzymes (trypsin, pepsin, proteinase K) were used to digest glycated BSA. The extent of modification depended on the selected oxo-compound. Reactivity increased progressively from glucose to glutardialdehyde (glucose<ribose<glyoxal<glutardialdehyde). Carboxymethylation of lysine (CML) was the main type of modification detected. The HPLC/MS method achieved higher coverage and a larger amount of CML was identified compared to CZE/MS.

Electrophoresis today and tomorrow: Helping biologists' dreams come true

Intensive research and development of electrophoresis methodology and instrumentation during past decades has resulted in unique methods widely implemented in bioanalysis. While two-dimensional electrophoresis and denaturing polyacrylamide gel electrophoresis in sodium dodecylsulfate are still the most frequently used electrophoretic methods applied to analyses of proteins, new miniaturized capillary and microfluidic versions of electromigrational methods have been developed. High-throughput electrophoretic instruments with hundreds of capillaries for parallel separations and laser-induced fluorescence detection of labeled DNA strands have been of key importance for the scientific and commercial success of the Human Genome Project. Another powerful method, capillary isoelectric focusing with pressurized and pH-driven mobilization, provides efficient separations and on-line sensitive detection of proteins, bacteria and viruses. Electrophoretic microfluidic devices can integrate single-cell injection, cell lysis, separation of its components and fluorescence or mass spectrometry detection. These miniaturized devices also proved the capability of single-molecule detection.

Investigations on the migration behavior of insulin and related synthetic analogues in CZE, MEKC and MEEKC employing different surfactants

The retention/migration behavior of insulin and five synthetic insulin analogues in CZE, MEKC and MEEKC employing seven different detergents within the latter two techniques has been investigated. Substantial changes in separation selectivity in MEKC could be observed for several insulins when moving from SDS to cholate-based micellar systems. Customized separations could be achieved by using mixtures of SDS and deoxycholate. A similar effect could be observed in MEEKC although the overall quality of MEEKC separations was inferior to those obtained with MEKC.

CE-TOF MS analysis of complex protein hydrolyzates from genetically modified soybeans--a tool for foodomics

A CE-TOF MS proteomic approach was applied for the analysis of hydrolyzates from complex soybean protein mixtures. After CE-TOF MS method development, the new approach provided the simultaneous analysis of more than 150 peptides from the soybean protein fraction soluble in ACN-water (80/20 v/v). The method is fast (about 30 min of analysis per sample) and is characterized by a relatively low running cost. The approach was used to study the substantial equivalence between a genetically modified variety of soybean compared with its traditional counterpart. No significant differences were found between the two studied soybeans based on the protein fraction studied. The capacity of the CE-TOF MS method to analyze complex mixtures of peptides in short times opens interesting possibilities in the growing Foodomics area.

CEC of phytochemical bioactive compounds

Although there are many publications related to technological or methodological developments of CEC, few focus on the analysis of natural products, especially phytochemical bioactive compounds. This review summarized the application of CEC in the analysis of phytochemical bioactive components, including flavonoids, nucleosides, steroids, lignans, quinones and coumarins, as well as fingerprint analysis of herbs. The strategies for optimization of CEC conditions and detection were also discussed.