| | Contents | |
| | | |
| |
| | | |
| | Preface | XV |
| | A Personal Foreword | XVII |
| | List of Contributors | XIX |
| I | Introduction to MS in bioanalysis | 1 |
| 1 | Mass Spectrometry in Bioanalysis -- Methods, Principles and Instrumentation Gérard Hopfgartner | 3 |
| 1.1 | Introduction | 3 |
| 1.2 | Fundamentals | 4 |
| 1.3 | Ionization Techniques | 10 |
| 1.3.1 | Electron Impact and Chemical Ionization | 10 |
| 1.3.2 | Atmospheric Pressure Ionization | 12 |
| 1.3.2.1 | Electrospray | 14 |
| 1.3.2.2 | Atmospheric Pressure Chemical Ionization | 17 |
| 1.3.2.3 | Photoionization | 19 |
| 1.3.2.4 | Multiple Ionization Source | 19 |
| 1.3.2.5 | Desorption Electrospray and Direct Analysis in Real Time | 20 |
| 1.3.3 | Matrix Assisted Laser Desorption Ionization | 21 |
| 1.4 | Mass Analyzers | 23 |
| 1.4.1 | Quadrupole Analyzers | 23 |
| 1.4.2 | Triple Quadrupole Mass Analyzer | 24 |
| 1.4.3 | Ion Trap Mass Spectrometry | 27 |
| 1.4.4 | Triple Quadrupole Linear Ion Trap | 30 |
| 1.4.5 | Time of Flight Mass Spectrometry | 33 |
| 1.4.6 | Fourier Transform Mass Spectrometry | 36 |
| 1.4.6.1 | Fourier Transform--Ion Cyclotron Resonance Mass Spectrometry | 36 |
| 1.4.6.2 | Orbitrap Mass Spectrometer | 37 |
| 1.5 | Ion Detectors | 38 |
| 1.6 | Practical Aspects and Applications in Bioanalysis | 41 |
| 1.6.1 | Introduction | 41 |
| 1.6.2 | Quantitative Analysis in Biological Matrices | 42 |
| 1.6.3 | Drug Metabolism | 45 |
| 1.6.4 | Analysis of Proteins | 49 |
| 1.7 | Perspectives | 54 |
| 1.8 | Common Definitions and Abbreviations | 58 |
| | References | 58 |
| II | Studying target-ligand interactions analyzing the ligand by MS | 63 |
| 2 | Drug Screening Using Gel Permeation Chromatography Spin Columns Coupled with ESI-MS Marshall M. Siegel | 65 |
| 2.1 | Introduction | 65 |
| 2.1.1 | Preface | 65 |
| 2.1.2 | Direct and Indirect ESI-MS Analysis of Non-covalent Drug--Protein Complexes | 65 |
| 2.1.3 | Advantages of GPC Spin Columns | 66 |
| 2.1.4 | Application of Equilibrium and Non-equilibrium Theory for the Analysis of GPC Spin Column Eluates | 68 |
| 2.1.4.1 | Sample Prepared Under Equilibrium Conditions Prior to Spin Column Treatment | 69 |
| 2.1.4.2 | Calculation for Predicting the Concentration of Sample Complex Eluted From the Spin Column | 69 |
| 2.1.4.3 | Estimation of Relative Binding Affinities from GPC Spin-Column/ESI-MS Data | 72 |
| 2.1.4.4 | Experimental Determination of the Kd Value from GPC Spin-Column/ESI-MS Data | 72 |
| 2.2 | Experimental | 73 |
| 2.2.1 | Spin Columns | 73 |
| 2.2.2 | Spin Column Media: Advantages and Disadvantages, Volatile vs Non-volatile Buffers | 74 |
| 2.2.3 | Preparing Non-covalent Complexes in Protein Buffer; Protein Concentration, Ligand Concentration, Incubation Time | 75 |
| 2.2.4 | Sample Organization: Single Samples vs Mixtures, Mixture Set-up: Compatibility of Components, Plate Set-up | 79 |
| 2.2.5 | Pooling Spin Column Eluates for Higher Throughput | 80 |
| 2.2.6 | Manual vs Robotic Instrumentation for Sample Preparation and Acquiring Spin Column Eluates | 80 |
| 2.2.7 | ESI Mass Spectrometer: ESI, APCI, Photodissociation, Positive/Negative Ionization | 81 |
| 2.2.8 | ESI Multi-sprayer (MUX) Technology; Sample Throughput; Protein Consumption | 82 |
| 2.2.9 | Reversed Phase (RP) HPLC ESI-MS Considerations | 83 |
| 2.2.10 | Protein Removal for Optimum Sensitivity | 84 |
| 2.2.11 | Data Reduction and Automated Interpretation of GPC Spin Column/ESI-MS Data | 84 |
| 2.3 | Results | 89 |
| 2.3.1 | Secondary Screens | 89 |
| 2.3.1.1 | GPC Spin Column/ESI-MS Drug Screening Demonstration Papers | 89 |
| 2.3.1.2 | Estrogen Receptor Target | 89 |
| 2.3.1.3 | Non-covalent Binding of Drugs to RNA/DNA Targets | 90 |
| 2.3.1.4 | Amgen Secondary Screens | 94 |
| 2.3.1.5 | Novartis Secondary Screens | 94 |
| 2.3.2 | Primary Screens | 94 |
| 2.3.2.1 | RGS4 Protein Target | 94 |
| 2.3.2.2 | Amgen Primary Screens | 98 |
| 2.3.2.3 | Novartis Primary Screens | 98 |
| 2.3.3 | Additional Spin Column Methods | 99 |
| 2.3.3.1 | Competition Experiments of Inhibitor Mixture with Protein Target | 99 |
| 2.3.3.2 | GPC Spin Column/ESI-MS Determination of Binding Sites | 101 |
| 2.3.3.3 | Obtaining MS EC50s and Kds for Ligands Non-covalently Bound to Protein Active Sites | 112 |
| 2.3.3.4 | Multiple Passes Through Spin Columns -- Finding Strongest Binders | 113 |
| 2.3.3.5 | Reverse Screening with GPC Spin Columns | 113 |
| 2.4 | Conclusions | 113 |
| 2.4.1 | GPC Spin Column/ESI-MS: Ease of Use, Mixture Analysis, High Speed, Reliability, Uncoupling of GPC from ESI-MS and HPLC ESI-MS | 113 |
| 2.4.2 | Comparison of GPC Spin Column/HPLC ESI-MS with Tandem Chromatographic Method of GPC/HPLC ESI-MS | 114 |
| 2.4.3 | Future Developments | 115 |
| 2.4.3.1 | MS and HPLC Improvements | 115 |
| 2.4.3.2 | Use of Automated Nanospray for Greater Sensitivity and Smaller Sample Size (Less Protein/Drug) | 115 |
| 2.4.3.3 | Microfluidic Systems: Sensitivity, High Speed | 116 |
| 2.4.3.4 | GPC Spin Column Eluates Analyzed by ESI/Ion Mobility/Mass Spectrometry | 116 |
| 2.4.3.5 | GPC Spin Columns with Matrixless MALDI-MS and Gyros GPC Microfluidic ESI/MALDI-MS System | 116 |
| | References | 117 |
| 3 | ALIS: An Affinity Selection--Mass Spectrometry System for the Discovery and Characterization of Protein--Ligand Interactions Allen Annis, Cheng-Chi Chuang, and Naim Nazef | 121 |
| 3.1 | Introduction | 121 |
| 3.1.1 | State of the Art | 122 |
| 3.1.1.1 | Spectroscopic and Biophysical Methods | 122 |
| 3.1.1.2 | Mass Spectrometry-based Methods | 123 |
| 3.2 | ALIS: An Affinity Selection--Mass Spectrometry System based on Continuous SEC | 124 |
| 3.2.1 | ALIS System Design | 126 |
| 3.3 | Discovery of Ligands from Combinatorial Libraries | 127 |
| 3.4 | Quantitative Binding Affinity Measurement | 130 |
| 3.4.1 | Theory | 131 |
| 3.4.2 | Simulations and Experimental Results | 134 |
| 3.5 | Competition-based Binding Site Determination and Affinity Ranking in Mixtures | 135 |
| 3.5.1 | Binding Site Classification | 136 |
| 3.5.2 | Affinity Ranking in Compound Mixtures | 140 |
| 3.6 | Protein--Ligand Dissociation Rate Measurement | 142 |
| 3.6.1 | Theory | 143 |
| 3.6.2 | Simulations | 145 |
| 3.6.3 | Experimental Results | 147 |
| 3.7 | Conclusions | 150 |
| 3.8 | Future Directions | 151 |
| | References | 152 |
| 4 | Library Screening Using Ultrafiltration and Mass Spectrometry Timothy E. Cloutier and Kenneth M. Comess | 157 |
| 4.1 | Introduction | 157 |
| 4.2 | Ultra-high Throughput Filtration-based Affinity Screening as a Discovery Tool | 163 |
| 4.2.1 | Affinity Selection/Mass Spectrometry | 163 |
| 4.2.2 | Primary Screening Strategy | 164 |
| 4.2.3 | Retesting and Deconvolution Strategy | 167 |
| 4.2.4 | Promiscuous Compound Filter | 168 |
| 4.2.5 | MurF Lead Discovery | 171 |
| 4.3 | Additional Affinity Screening Methodology That Includes Mass Spectrometry-based Readout | 177 |
| 4.3.1 | Pulsed Ultrafiltration MS | 177 |
| 4.4 | Conclusions and Future Directions | 180 |
| | References | 181 |
| 5 | Continuous-flow Systems for Ligand Binding and Enzyme Inhibition Assays Based on Mass Spectrometry Hubertus Irth | 185 |
| 5.1 | Introduction | 185 |
| 5.2 | Continuous-flow Enzyme Assays Based on Mass Spectrometry | 186 |
| 5.2.1 | Assay Principle | 186 |
| 5.2.2 | ESI-MS Assay of Cathepsin B | 188 |
| 5.2.2.1 | MS Assay Development for Cathepsin B | 188 |
| 5.2.2.2 | Compatibility of Cathepsin B Assay with MS Detection | 188 |
| 5.2.2.3 | On-line Coupling of MS-based Cathepsin B Assay to HPLC | 190 |
| 5.2.2.4 | Screening of Natural Products for Cathepsin B Activity | 192 |
| 5.2.3 | ESI-MS Assay of Acetylcholinesterase | 194 |
| 5.2.3.1 | MS Assay Development for Acetylcholinesterase | 194 |
| 5.2.3.2 | Assay Validation and Stability | 197 |
| 5.2.3.3 | Screening of Natural Products for Acetylcholinesterase Activity | 197 |
| 5.2.4 | Miniaturization of Electrospray MS Assays | 198 |
| 5.2.4.1 | Chip-based Electrospray MS Assays | 198 |
| 5.2.4.2 | Chip Performance | 199 |
| 5.2.4.3 | Sensitivity of the Chip-based MS Screening System | 200 |
| 5.3 | Continuous-flow Ligand Binding Assays Based on Mass Spectrometry | 200 |
| 5.3.1 | Assay Principle | 200 |
| 5.3.2 | Optimization of MS Conditions | 201 |
| 5.3.3 | On-line Continuous-flow Biochemical Interaction | 202 |
| 5.3.4 | Monitoring Bioactive Compounds | 204 |
| 5.3.5 | Antibody--Antigen Interactions | 205 |
| 5.3.6 | Continuous-flow Multi-protein Binding Assays Using Electrospray MS | 205 |
| 5.4 | MS Assay Based on Dissociation of Isolated Protein--Ligand Complexes | 207 |
| 5.4.1 | Assay Set-up | 207 |
| 5.4.2 | Flow Injection Label-free MS Assay | 209 |
| 5.4.3 | Flow Injection Label-free MS Assay Screening of Natural Extracts | 211 |
| 5.5 | Future Prospects | 211 |
| | References | 213 |
| 6 | Frontal Affinity Chromatography -- Mass Spectrometry for Ligand Discovery and Characterization Nora Chan, Darren Lewis, Michele Kelly, Ella S.M. Ng, and David C. Schriemer | 217 |
| 6.1 | Introduction | 217 |
| 6.1.1 | The Basic Frontal Method | 218 |
| 6.1.2 | FAC -- Basic Theory | 220 |
| 6.1.3 | FAC Advantages | 221 |
| 6.1.4 | FAC Disadvantages | 223 |
| 6.2 | Enabling FAC with MS Detection | 224 |
| 6.2.1 | Direct FAC-MS Methods for Compound Binding Data | 224 |
| 6.2.2 | Direct Method for Discovering and Ranking Multiple Ligands | 226 |
| 6.2.3 | Indirect Methods | 232 |
| 6.3 | System Advancements -- Fluidics, Immobilization, Detection | 235 |
| 6.3.1 | Column | 235 |
| 6.3.2 | System | 239 |
| 6.3.3 | Breakthrough Curve Detection and Data Analysis | 241 |
| 6.4 | Select Applications | 242 |
| 6.5 | Summary and Evaluation | 243 |
| | References | 244 |
| 7 | MS Binding Assays -- An Alternative to Radioligand Binding Georg Höfner, Christine Zepperitz, and Klaus T. Wanner | 247 |
| 7.1 | Introduction | 247 |
| 7.2 | Radioligand Binding Assays | 248 |
| 7.2.1 | General Principle | 248 |
| 7.2.1.1 | Saturation Assays | 248 |
| 7.2.1.2 | Competition Assays | 249 |
| 7.2.1.3 | Kinetic Assays | 250 |
| 7.2.2 | Application | 251 |
| 7.2.3 | Disadvantages and Alternatives | 252 |
| 7.3 | MS Binding Assays | 254 |
| 7.3.1 | MS Binding Assays Quantifying the Nonbound Marker | 255 |
| 7.3.1.1 | Competition Assays for D1 and D2 Dopamine Receptors | 257 |
| 7.3.1.2 | Library Screening and Competition Assays for -Opioid Receptors | 263 |
| 7.3.2 | MS Binding Assays Quantifying the Bound Marker | 267 |
| 7.3.2.1 | Saturation Assays for mGAT1 | 268 |
| 7.3.2.2 | Competition Assays for mGAT1 | 272 |
| 7.3.2.3 | Kinetic Assays for mGAT1 | 272 |
| 7.4 | Summary and Perspectives | 276 |
| | References | 278 |
| 8 | Laser Desorption Assays -- MALDI-MS, DIOS-MS, and SAMDI-MS Martin Vogel, Andy Scheffer, André Liesener, and Uwe Karst | 285 |
| 8.1 | MALDI-MS Assays | 285 |
| 8.1.1 | Principles of MALDI | 285 |
| 8.1.2 | Application of MALDI-MS in Bioanalysis | 287 |
| 8.2 | DIOS: Desorption/Ionization on Silicon | 289 |
| 8.2.1 | Principles of DIOS | 289 |
| 8.2.2 | Application of DIOS in Bioanalysis | 292 |
| 8.3 | SAMDI: Self-assembled Monolayers for MALDI-MS | 295 |
| 8.3.1 | Principles of SAMDI-MS | 295 |
| 8.3.2 | Application of SAMDI in Bioanalysis | 297 |
| 8.4 | Conclusion | 299 |
| | References | 300 |
| III | Studying target-ligand interactions analyzing intact target-ligand complexes by MS | 303 |
| 9 | Tethering: Fragment-based Drug Discovery by Mass Spectrometry Mark T. Cancilla and Daniel A. Erlanson | 305 |
| 9.1 | Introduction | 305 |
| 9.2 | Reduction to Practice | 307 |
| 9.2.1 | Technique | 307 |
| 9.2.2 | Advantages | 310 |
| 9.3 | Finding Fragments: Thymidylate Synthase Proof of Principle | 310 |
| 9.4 | Finding and Linking Fragments in One Step: Tethering with Extenders | 312 |
| 9.4.1 | Caspase-3 | 312 |
| 9.4.2 | Caspase-1 | 316 |
| 9.5 | Conclusions | 316 |
| | References | 318 |
| 10 | Interrogation of Noncovalent Complexes by ESI-MS: A Powerful Platform for High Throughput Drug Discovery Steven A. Hofstadler and Kristin A. Sannes-Lowery | 321 |
| 10.1 | Analysis of Noncovalent Complexes by ESI-MS | 321 |
| 10.1.1 | Solution Conditions | 321 |
| 10.1.2 | Proteins | 322 |
| 10.1.3 | Oligonucleotides | 323 |
| 10.2 | Multitarget Affinity/Specificity Screening | 328 |
| 10.3 | Multitarget Affinity/Specificity Screening in a High Throughput Format | 329 |
| 10.4 | Affinity/Specificity | 330 |
| 10.5 | SAR by MS | 332 |
| 10.6 | Future Directions | 333 |
| | References | 335 |
| IV | Studying target-ligand interactions analyzing the target binding site by MS | 339 |
| 11 | Quantification of Protein--Ligand Interactions in Solution by Hydrogen/Deuterium Exchange (PLIMSTEX) Mei M. Zhu, David Hambly, and Michael L. Gross | 341 |
| 11.1 | Introduction | 341 |
| 11.2 | The PLIMSTEX Method | 342 |
| 11.2.1 | A General Protocol of H/D Exchange and LC/MS Analysis for PLIMSTEX | 342 |
| 11.2.2 | Determination and Interpretation of the Titration Curves | 343 |
| 11.3 | Applications of PLIMSTEX | 345 |
| 11.3.1 | Determination of Association Constant (Ka), Stoichiometry (n), and Protection ( Di) | 345 |
| 11.3.2 | Ras-GDP Interacting with Mg2+: A 1:1 Protein:Metal Ion Interaction | 347 |
| 11.3.2.1 | Kinetic Study of Forward H/D Exchange Ras-GDP with Different [Mg2+] | 347 |
| 11.3.2.2 | PLIMSTEX Results for Ras-GDP Titrated with Mg2+ | 348 |
| 11.3.2.3 | Interpretation of PLIMSTEX Results with H/D Exchange Kinetics | 349 |
| 11.3.2.4 | Application of PLIMSTEX to Relatively Weak Protein--Ligand Binding | 350 |
| 11.3.2.5 | Experimental Issues Regarding Using Metal Chelators | 350 |
| 11.3.3 | Apo-CaM Interacting with Ca2+: A 1:4 Protein:Metal Ion Interaction | 351 |
| 11.3.3.1 | PLIMSTEX Results for CaM and Intermediate Protein--Ligand Binding Species | 351 |
| 11.3.3.2 | PLIMSTEX in Biologically Relevant Media and High Ionic Strength | 352 |
| 11.3.4 | Apo-IFABP and Oleate: A Protein--Small Organic Molecule Interaction | 353 |
| 11.3.5 | Holo-CaM and Melittin: A Protein--Peptide Interaction | 354 |
| 11.3.5.1 | PLIMSTEX Curves Under Different Holo-CaM Concentrations | 355 |
| 11.3.6 | Self-association of Insulin: A Protein--Protein Interaction | 356 |
| 11.3.6.1 | Modified Version of PLIMSTEX for Insulin Self-association | 356 |
| 11.4 | Features of PLIMSTEX | 357 |
| 11.4.1 | Determines Ki, Stoichiometry, and Protection ( Di) | 357 |
| 11.4.2 | Requires Low Quantities of Protein | 357 |
| 11.4.3 | Relies Only on MS to Measure m/z And Not Solution Concentration | 358 |
| 11.4.4 | Works in Biologically Relevant Media at High Ionic Strength | 359 |
| 11.4.5 | Does Not Need Specially Labeled Protein or Ligand | 359 |
| 11.4.6 | Avoids Perturbation of the Binding Equilibrium | 360 |
| 11.4.7 | Has Potential for Peptide Resolution | 360 |
| 11.4.8 | Current Challenges and Future Directions | 360 |
| 11.5 | Fast Radical Footprinting for Protein--Ligand Interaction Analysis | 361 |
| 11.5.1 | Rationale for Hydroxyl Radicals as a Probe | 362 |
| 11.5.2 | Methods for Generating Hydroxyl Radicals | 362 |
| 11.5.3 | Fast Photochemical Oxidation of Proteins | 363 |
| 11.5.4 | Locating the Sites of Oxidation | 364 |
| 11.5.5 | Application of FPOP to Apomyoglobin | 364 |
| 11.5.6 | Advantages of FPOP | 366 |
| 11.6 | Potential Applications in Drug Discovery | 367 |
| | References | 368 |
| 12 | Protein-targeting Drug Discovery Guided by Hydrogen/Deuterium Exchange Mass Spectrometry (DXMS) Yoshitomo Hamuro, Stephen J. Coales, and Virgil L. Woods Jr | 377 |
| 12.1 | Introduction | 377 |
| 12.2 | Theory of H/D Exchange | 378 |
| 12.2.1 | Amide H/D Exchange | 378 |
| 12.2.2 | Protection Factor | 378 |
| 12.2.3 | Backbone Amide Hydrogens as Thermodynamic Sensors | 379 |
| 12.3 | Overview of H/D Exchange Technologies | 380 |
| 12.3.1 | On Exchange Reaction | 380 |
| 12.3.2 | Quench of Exchange Reaction | 380 |
| 12.3.3 | Protein Fragmentation by Proteolysis | 381 |
| 12.3.4 | Digestion Optimization | 381 |
| 12.3.5 | HPLC Separation | 381 |
| 12.3.6 | Mass Analysis | 381 |
| 12.3.7 | Automation of H/D Exchange by MS | 382 |
| 12.3.8 | Automated Data Analysis | 383 |
| 12.4 | DXMS-guided Design of Well Crystallizing Proteins | 383 |
| 12.4.1 | Disordered Regions and Protein Crystallography | 383 |
| 12.4.2 | Poorly Crystallizing Proteins Contain Substantial Disordered Regions | 384 |
| 12.4.3 | Disorder-depleted Mutant Preserved Ordered Structure | 384 |
| 12.4.4 | Disorder-depleted Mutant Improved Crystallization Efficiency and Produced High Resolution Structure | 384 |
| 12.5 | Rapid Characterization of Protein Conformational Change with DXMS | 385 |
| 12.5.1 | Human Growth Hormone | 386 |
| 12.5.2 | H/D Exchange of hGH | 386 |
| 12.5.3 | Free Energy Change upon Folding of hGH | 386 |
| 12.6 | Application of H/D Exchange to Protein--Small Molecule Ligand Interactions | 388 |
| 12.6.1 | p38 Mitogen-activated Protein Kinase | 388 |
| 12.6.2 | H/D Exchange of p38 MAP Kinase | 389 |
| 12.6.3 | Peroxisome Proliferator-activated Receptor {g} | 390 |
| 12.6.4 | H/D Exchange of PPAR{g} | 390 |
| 12.7 | DXMS-guided Design of Small Molecules that Target Protein--Protein Interaction Surfaces | 391 |
| 12.8 | Optimal Formulation and Quality Control of Whole-protein Therapeutics with DXMS | 393 |
| 12.9 | Conclusions | 394 |
| | References | 394 |
| V | MS in early pharmacokinetics | 399 |
| 13 | Mass Spectrometry in Early Pharmacokinetic Investigations Walter A. Korfmacher | 401 |
| 13.1 | Introduction | 401 |
| 13.2 | HPLC-MS/MS Overview | 402 |
| 13.3 | In Vitro Applications | 405 |
| 13.4 | In Vivo Applications | 406 |
| 13.5 | Rapid Method Development | 408 |
| 13.6 | Increasing Throughput in HPLC-MS/MS | 410 |
| 13.7 | Matrix Effects | 411 |
| 13.8 | Discovery PK Assay Rules | 413 |
| 13.9 | New Technology in LC-MS | 415 |
| 13.10 | Conclusion | 419 |
| | References | 419 |
| | Index | 429 |