binding-kinetics

A guide to drug-target binding kinetics, which describes how quickly a drug binds to and leaves a target, not only how tightly it binds overall. It covers measurements such as kon, koff, KD, and residence time, plus laboratory data and simulations.

In plain words
What is it for?
Analyzing SPR or ITC experiments, fitting binding models, estimating residence times from simulations, building kinetic prediction models, and prioritizing compounds by binding speed or duration.
Why use it?
It helps compare compounds by how long they remain bound and interpret binding experiments beyond a single affinity number.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/kdevos12/alkyl/binding-kinetics
Any agent
npx skills add Kdevos12/ALKYL --skill binding-kinetics
Clone the repo
git clone --depth 1 https://github.com/Kdevos12/ALKYL

Made for: Claude Code, Codex.

Per session 58 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 820 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00058 $0.00820
Opus 5 $0.00029 $0.00410
Sonnet 5 $0.00012 $0.00164
Haiku 4.5 $0.00006 $0.00082

Measured 2d ago against content hash 516542ca6a5b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

binding-kinetics scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/binding-kinetics/SKILL.md · 69 lines

How it starts

The opening of the file, as written. The whole thing — 69 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Binding Kinetics

Purpose

Analyze, predict, and optimize drug-target binding kinetics: on-rates (kon), off-rates (koff), residence time (RT = 1/koff), thermodynamic signatures (ΔH/ΔS), and structure-kinetics relationships (SKR).

When to Use This Skill

  • Analyzing SPR sensorgrams (Biacore/Sierra)
  • Fitting ITC thermograms for ΔH/ΔS/ΔG
  • Computing residence time from MD simulations (τRAMD, metadynamics)
  • Building QSAR models for koff/kon
  • Interpreting kinetic selectivity vs equilibrium selectivity
  • Prioritizing compounds by residence time, not just KD

Reference Files

File Content
references/kinetics-theory.md kon/koff/KD/RT definitions, kinetic selectivity, two-state binding, conformational selection vs induced fit, thermodynamic signatures
references/spr-analysis.md SPR sensorgrams, 1:1 Langmuir fitting, two-state model, Rmax/Rtheor, bulk correction, Biacore data parsing, Python fitting
references/itc-analysis.md ITC thermogram integration, n/KD/ΔH/ΔS/ΔG fitting, SEDPHAT equivalents in Python, van't Hoff, enthalpy-entropy compensation
references/residence-time-md.md τRAMD (random acceleration MD), funnel metadynamics, WTmetaD koff estimation, HTMD τRAMD Python, unbinding pathway analysis
references/kinetic-qsar.md Structure-kinetics relationships (SKR), features for koff/kon models, kinetic maps (LE vs kinetic efficiency), koff cliff detection

Quick Routing

"Fit my SPR data"spr-analysis.md

"Fit my ITC experiment"itc-analysis.md

"Compute residence time from MD"residence-time-md.md

"Build a model to predict koff"kinetic-qsar.md

"Why does my drug work despite poor KD?"kinetics-theory.md

Key Relationships

# Core kinetic relationships
KD = koff / kon                    # M (equilibrium dissociation constant)
pKD = -log10(KD)                   # analogous to pIC50
RT = 1 / koff                      # seconds (residence time)
t_half = ln(2) / koff              # seconds (half-life of complex)

# Thermodynamics
ΔG = RT_gas * ln(KD)               # kcal/mol (RT_gas = 0.592 at 298K)
ΔG = ΔH - T*ΔS                    # enthalpy-entropy decomposition

# Typical drug ranges
# kon:  10^4 – 10^7 M^-1 s^-1
# koff: 10^-5 – 10^-1 s^-1
# KD:   nM – µM
# RT:   10 s – 10^5 s (hours)

Read the full file on GitHub · 69 lines

Files

What ships with it

5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 69 lines · 0 tokens per session scan A 516542ca6a5b

Subscribe to this mod's changes

binding-kinetics is a skill published in the GitHub repository Kdevos12/ALKYL (6 stars, last pushed 5mo ago), licensed MIT. It adds 58 tokens to every session and 820 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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