Chapter Four · failure evidence
What Enzyme Activity & Kinetic Assays got wrong, from 27 dissertations
The evaluated records describe experimental and analytical challenges encountered when conducting enzyme activity measurements and kinetic assays. Across these studies, researchers experienced optical interferences, violations of standard kinetic assumptions, instrument timescale mismatches, and chemical or electrochemical bottlenecks. These records come from PhD theses at 15 institutions, 2021 to 2026. Each links to its thesis. They were extracted by language models reading the full text, so treat each as a lead to read, not a verdict.
Standard Michaelis-Menten and initial-rate kinetic assumptions fail under non-ideal experimental conditions
Researchers found that Michaelis-Menten kinetic assumptions failed when enzyme and substrate concentrations were comparable, when initial rates did not plateau, or when saturation was substoichiometric. In addition, initial-rate fittings could not capture full time-course reaction yields, and reaching required substrate concentrations was prevented by peptide insolubility and inner filter effects.
Tried and failed
initial-rate kinetic parameter fitting for reaction modeling applied to enzymatic synthesis yield prediction. Outcome: did not generalise. Reason: initial-rate kinetic parameters failed to accurately capture full time-course reaction yields
Continuous enzymatic reactive crystallization of beta-lactam antibiotics · Georgia Tech
Considered and rejected
Considered and rejected: Standard Michaelis-Menten kinetics for DivJ/PleC phosphotransfer were rejected because enzyme and substrate concentrations are comparable, violating [S] >> [E] assumptions.
Considered and rejected
Considered and rejected: Rejected using pure Michaelis-Menten kinetics, adopting quadratic master equations with explicit nucleotide exchange to handle substoichiometric DnaJ saturation.
Why do we need so many proteins? A physical insight into the collaboration of Hsp70 and DnaJ · EPFL
Considered and rejected
Considered and rejected: Rejected nonlinear Michaelis-Menten regression for CKM R132C kinetics because initial rate remained linear without plateauing at tested ATP concentrations, using a linear fit instead
Impact of interindividual differences on muscle-type creatine kinase: implications for tenofovir-based PrEP · JScholarship
Considered and rejected
Considered and rejected: Rejected traditional Michaelis-Menten initial-rate kinetics to determine 3CLpro catalytic efficiency because 10x KM required millimolar substrate concentrations blocked by the inner filter effect and peptide insolubility
Exploring and Exploiting Ribonuclease 1: from Protein Biochemistry to Protein Engineering · MIT
Transient lag phases and instrument timescale limits distort continuous and single-molecule kinetic assays
Coupled and progress-curve assays frequently suffered from substrate-dependent lag phases that overestimated rate constants or obscured steady-state kinetics. Other kinetic measurements failed when reaction rates fell below instrument operational timescales or when stochastic enzyme dynamics and systematic probe drift caused severe variance.
Tried and failed
stopped-flow fluorescence spectroscopy for transient kinetics applied to basal enzyme reaction kinetics. Outcome: too slow. Reason: reaction rate was below the detection threshold for the instrument's operational timescale
Considered and rejected
Considered and rejected: FucA (fuculose 1-phosphate aldolase) coupled assay was rejected for steady-state kinetics of MtnA because of a significant lag phase at low substrate concentrations.
Mechanistic Investigation of the Reaction Catalyzed by 5-Methylthioribose-1-phosphate Isomerase in the Methionine Salvage Pathway · DSpace at SUNY Buffalo
Tried and failed
measuring dimerization dissociation constant via enzymatic progress curves applied to homodimeric viral protease kinetics. Reason: concentration-dependent lag phase in high salt overestimated pseudo-first-order rate constants
Exploring and Exploiting Ribonuclease 1: from Protein Biochemistry to Protein Engineering · MIT
Considered and rejected
Considered and rejected: Rejected four-parameter logistic end-point fitting of SWCNT traces because critical parameters (x0, h) varied systematically with probe time rather than reflecting true invariant enzymatic kinetics.
Optical probes and measurement systems for enzyme activity and fermentation process monitoring · Iowa State
Considered and rejected
Considered and rejected: Single-parameter dwell-time/current-blockade analysis rejected because stochastic motor enzyme kinetics caused high variance and could not cleanly distinguish bound from unbound states.
Optical interference and background matrix absorbance obscure spectrophotometric activity detection
Optical turbidity, background aromatic compounds, and increasing tissue volume caused non-catalytic absorbance changes that overwhelmed enzymatic signals. These spectrophotometric limitations caused poor signal-to-noise ratios, required excessive protein inputs, and prevented the tracking of substrate-specific products.
Tried and failed
spectrophotometric absorbance detection in turbid matrices applied to enzymatic screening in complex wastewater. Outcome: no signal. Reason: optical turbidity and background aromatic compounds interfered directly with absorbance-based measurement
Applications of Systems-Driven Protein Engineering Toward In Situ Water Safety Technologies · Cornell
Tried and failed
spectrophotometric coupled-enzyme activity assay applied to enzyme acting as own substrate. Outcome: no signal. Reason: Low signal-to-noise ratio, high required protein concentration, and inability to determine Michaelis-Menten kinetic parameters.
Considered and rejected
Considered and rejected: Phosphomolybdate spectrophotometric method rejected for mixed-substrate kinetics due to inability to track substrate-specific Pi
Considered and rejected
Considered and rejected: Abandoned measuring ACE enzymatic activity in maternal kidney and placental lysates because optical density changes were driven solely by absorbance of increasing tissue volume rather than catalytic activity.
Defining the impact of paternal diet on maternal cardiometabolic ill-health in late gestation · University of Nottingham Repository
Assay dilution issues, missing cofactors, and unreplicable screens compromise enzyme activity testing
In vitro activity assays failed when enzymes lacked essential partner proteins, cofactors, or proper substrate stereochemistry to catalyze reactions. Furthermore, unmonitored sample dilutions caused severe losses of enzymatic activity or buffer precipitation, while single-run modulation screens failed to reproduce initial trends in follow-up trials.
Tried and failed
enzymatic assays and HPLC applied to organic acid quantification in fruit juice. Outcome: unstable. Reason: lack of correlation upon dilution and buffer precipitation during analysis
BROADENING THE BASE OF APPLE GENETICS: A STUDY OF TRAITS USING MALUS PRUNIFOLIA · Cornell
Lost to a baseline
Fixed 1:40 dilution of Batch 2 solubilizate without IPC suffered an over 50% decrease in enzymatic activity compared to Batch 1.
Quality by Design strategies in Inclusion Body processing · DSpace-CRIS at TU Wien
Tried and failed
single-run kinetic inhibition and activation screening assays applied to small molecule enzyme activity modulation. Outcome: did not generalise. Reason: initial weak inhibition and activation trends could not be replicated in subsequent trials
Tried and failed
enzymatic S-adenosylmethionine-dependent methyltransferase assay applied to synthetic substrate analogue. Outcome: no signal. Reason: the methyltransferase required additional cofactors, partner proteins, or a different substrate stereochemistry to act
Biosynthetic studies of thiosugar natural products ; Mechanistic studies of hyoscyamine 6 [beta]-hydroxylase · UT Austin
Left open by the authors
Problems the authors named and did not get to.
Left open
Test the STAR-based comparator using light-inducible promoters in Chi.bio turbidostats to measure dynamic RNA-RNA unbinding and sequestration kinetics. Blocker: Requires a wet lab, Chi.bio turbidostat hardware, engineered E. coli strains, and physical reagents
Towards engineering microbial consortia using RNA-based genetic controllers · Imperial
Left open
Determine the enzyme activity recovery rate after cross-linking compared to the crude extract under industrial parameters. Blocker: Requires wet lab equipment, sludge samples, and physical enzyme extraction and activity assay apparatus
Enzyme recovery from biological wastewater treatment · Imperial
Left open
Determine and compare the erythritol synthesis capacity and enzyme kinetics across human ADH1 genetic variants. Blocker: Requires wet-lab protein expression, purification, and spectrophotometric kinetic assays.
Understanding Reductive Enzymes in the Erythritol Biosynthesis Pathway: “The Secrets of Sweet Blood” · Cornell
Left open
Measure enzyme kinetics data for Vibrio natriegens to parameterize resource balance analysis and proteome-constrained models. Blocker: Requires wet-lab biochemistry and experimental enzyme assays for V. natriegens proteins
Left open
Measure electron transfer rates and B-branch kinetics in PsaB-E670C and PsaB-W677C mutant Photosystem I complexes. Blocker: Requires wet lab culturing of mutant Synechocystis, protein purification, spin labeling, and spectroscopic measurement apparatus.
Directionality of electron transfer within Photosystem I complex · Iowa State
Left open
Quantify the calibration factor gamma relating RFU to molar concentration of mCherry protein for arsenic biosensor kinetics. Blocker: Requires wet lab experiments with purified mCherry protein and fluorometry apparatus.
Left open
Test SBP-catalyzed enzymatic removal of acetaminophen and parabens at low concentrations representative of wastewater treatment plant effluents. Blocker: Requires a wet lab, soybean peroxidase enzyme, target chemical contaminants, and analytical equipment (e.g., HPLC-UV).
Soybean Peroxidase Catalyzed Oligomerization of Acetaminophen and Selected Parabens for Wastewater Treatment · Scholarship at UWindsor Institutional Repository
Left open
Characterize individual kinetics and activity of CgtA/MBP-Δ15CgtAII and MBP-WlaN/CgtB across varied pH, temperature, and substrate concentrations. Blocker: Requires a biochemistry wet lab, recombinant enzymes, lipid bilayers, and analytical assays to measure kinetics.
Left open
Investigate the role of dispersion interactions in the kinetics of binding and activation of other weak ligands to transition metal complexes. Blocker: Requires wet lab chemical synthesis and experimental kinetic measurements (e.g., stopped-flow spectrophotometry).
Left open
Test biotinylated probe purification, enzymatic USER excision, or electrophoretic trafficking of cleaved bead barcodes to resolve HYPR-space index swapping and background. Blocker: Requires a wet lab, molecular biology assays, and physical Slide-seq/HYPR-space experimental setups.
Technologies for assaying the spatial position of biomolecules in situ · Harvard
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