Membrane Protein Extinction Coefficient ε₂₈₀ Calculator
Compute the 280 nm molar extinction coefficient of a membrane protein from its amino-acid sequence. ProtParam method; enter disulfide count for cystine contribution. 100% in-browser — your sequence is never uploaded.
- 1ProtParam ε₂₈₀ = nW·5500 + nY·1490 + nSS·125
ε = 0·5500 + 1·1490 + 0·125 = 1,490 M⁻¹cm⁻¹
🔒 100% client-side — your data is computed in the browser and never uploaded.
Cite this tool
ToolJolt. Membrane Protein Extinction Coefficient ε₂₈₀ Calculator. ToolJolt Chemistry & Lab Tools; 2026. https://tooljolt.comNeed a fast, reliable membrane protein extinction coefficient ε₂₈₀ calculator? This free tool computes the answer the moment the page loads and updates live as you type — no sign-up, no installs.
About Membrane Protein Extinction Coefficient ε₂₈₀ Calculator
Compute the 280 nm molar extinction coefficient of a membrane protein from its amino-acid sequence. ProtParam method; enter disulfide count for cystine contribution. 100% in-browser — your sequence is never uploaded. The calculation uses ε₂₈₀ = nW·5500 + nY·1490 + nSS·125. Why accuracy here pays off: The extinction coefficient sets every A280 concentration you report; the pI decides your ion-exchange and solubility strategy. These numbers underpin purification and quantitation. Membrane Protein: ProtParam method; enter disulfide count for cystine contribution. Mistakes that trip people up: ignoring post-translational modifications; forgetting cystine (disulfide) contributions to ε280; using reduced vs oxidized ε in the wrong context. No account, no upload, no tracking of your inputs — the result is generated on your machine, which makes it reproducible, private and citable in published work.
How to use Membrane Protein Extinction Coefficient ε₂₈₀ Calculator
- 1Enter your input values.
- 2Read the headline result and the supporting figures, which recompute as you type.
- 3Open “Worked example with your numbers” to see the substituted formula step by step.
- 4Copy the result, or use the cite-this-tool snippet for your methods section.
Why use Membrane Protein Extinction Coefficient ε₂₈₀ Calculator?
- ✓Mobile-friendly and completely free, with no sign-up or usage caps
- ✓Built on a sourced, unit-tested formula for protein and peptide characterization
- ✓Links to related protein and peptide characterization calculators so you can finish the whole workflow
- ✓Copy-ready result and a one-line “cite this tool” snippet for your methods section
- ✓Designed for protein biochemists, structural biologists and assay developers who need a trustworthy answer fast
Frequently asked questions
Any tips specific to this calculation?+
Membrane Protein: ProtParam method; enter disulfide count for cystine contribution. Also watch out for: ignoring post-translational modifications and assuming pI from sequence equals experimental pI exactly.
Is this membrane protein extinction coefficient ε₂₈₀ calculator free to use?+
Yes. It is completely free, needs no sign-up, and runs entirely in your browser — there are no usage limits.
What formula does it use?+
It uses ε₂₈₀ = nW·5500 + nY·1490 + nSS·125 The full worked example is shown beneath the result so you can verify each step.
What are the most common mistakes here?+
In protein and peptide characterization, watch for: forgetting cystine (disulfide) contributions to ε280; using reduced vs oxidized ε in the wrong context; assuming pI from sequence equals experimental pI exactly; ignoring post-translational modifications. This tool shows the working so you can catch these before they cost an experiment.
Does my data leave my device?+
No. All computation happens locally in your browser. Nothing you enter — sequences, concentrations or measurements — is uploaded to any server, so it is safe for confidential work.
Can I cite this tool?+
Yes — use the “Cite this tool” snippet on the page. Many users link these calculators from methods sections, lab SOPs and teaching materials.
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