catalytically perfect enzyme

Encounter-limited efficiency

The defining claim concerns catalytic efficiency approaching a diffusion-controlled association limit, with few futile encounters; it does not mean unlimited catalytic speed. See [The Moderately Efficient Enzyme: Futile Encounters and Enzyme Floppiness](https://pubmed.ncbi.nlm.nih.gov/26219075/).

1. What quantitative criterion and uncertainty range qualify this enzyme-substrate pair as approaching its encounter limit? definition
2. Does the claim concern low-substrate catalytic efficiency, saturated turnover or a different kinetic quantity? boundary

Variant, substrate and direction

Record the enzyme variant, active assembly, cofactor state, substrate species and reaction direction before attaching kinetic evidence.

1. Which accession, sequence variant and active molecular form were actually assayed? provenance
2. Which substrate species, reaction direction and required cosubstrates delimit the classification? boundary

Efficiency and active-site basis

Record kcat, Km and their ratio where identifiable, or a directly measured low-substrate specificity constant, with active-site normalization and uncertainty.

1. What measurements determine kcat/Km, and what uncertainty follows from the data and fitting procedure? measurement
2. How was catalytically active-site concentration established, including inactive enzyme and oligomer stoichiometry? measurement

Valid specificity constant

Require a kinetic model appropriate to the reaction and controls for assay limitations before interpreting a fitted ratio as encounter efficiency.

1. Are substrate inhibition, cooperativity, reversibility or multiple substrates relevant, and how does the chosen model handle them? boundary
2. What controls exclude mixing dead time, detector limits, substrate depletion and coupling-enzyme limitation? measurement

Condition-specific encounter limit

Record how diffusion, encounter geometry, electrostatic effects and medium properties enter the chosen encounter-rate estimate; distinguish whole-surface collision from productive active-site access.

1. How was the encounter-rate limit measured or calculated for this substrate and enzyme under the assay conditions? measurement
2. Does the comparator describe any molecular collision, active-site arrival or formation of a catalytically competent complex? definition

Diffusion perturbation controls

Viscosity perturbations need controls for direct solvent effects on catalysis; such confounding was demonstrated in an alkaline-phosphatase study. See [Alkaline phosphatase is an almost perfect enzyme](https://pubmed.ncbi.nlm.nih.gov/8068674/).

1. How does kcat/Km respond to viscosity changes after controlling for effects on enzyme structure, substrate activity and catalytic chemistry? measurement
2. What independent evidence separates substrate encounter limitation from conformational gating, chemistry or product-release limitation? measurement

Regime-dependent intervention

Record whether the intended operation uses dilute or saturating substrate and whether substrate delivery differs from the assay environment before selecting an intervention.

1. At the intended substrate and cosubstrate concentrations, which validated rate expression predicts performance? action
2. Would changing substrate delivery, enzyme concentration or catalytic-cycle kinetics address the measured limitation? action

Evidence-bounded classification

Attach each assessment to the primary measurements actually examined, preserve conflicting results and require reassessment when the molecular system or environment changes materially.

1. Which primary experiments support this classification, and which claims remain available only through secondary reports? provenance
2. Which variant, substrate, immobilization or environmental changes require new measurements before the classification is reused? boundary

Check these first

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these check these first hold for the sense of catalytically perfect enzyme this model covers, and on what evidence? provenance

Identifiers and schemes

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these identifiers and schemes hold for the sense of catalytically perfect enzyme this model covers, and on what evidence? provenance

Real-world use

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these real-world use hold for the sense of catalytically perfect enzyme this model covers, and on what evidence? provenance

Typical measurements

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these typical measurements hold for the sense of catalytically perfect enzyme this model covers, and on what evidence? provenance

Failure modes and hazards

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these failure modes and hazards hold for the sense of catalytically perfect enzyme this model covers, and on what evidence? provenance

Neighbouring kinds and how to tell them apart

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these neighbouring kinds and how to tell them apart hold for the sense of catalytically perfect enzyme this model covers, and on what evidence? provenance