Peptide Mapping

Sequence-level evidence for peptide identity, by digesting the peptide and measuring the fragments.

How it works

The peptide is cut at predictable points by an enzyme or a chemical reagent. The fragments are separated by liquid chromatography and measured by mass spectrometry. Each fragment is matched against the fragments expected from the stated sequence.

A mapping comparison evaluates the observed fragments against the expected sequence. Interpretation depends on sequence coverage and the quality of the fragment evidence.

Three ways to confirm identity

Routine identity (HPLC, RT and UV)

Compares the main peak's retention time and UV response with a reference standard. Part of routine purity testing.

Intact mass (LC-MS)

Measures the molecular mass of the whole peptide. Confirms the mass matches; different structures can share a mass.

Peptide mapping

Cuts the peptide into fragments and measures each one, so the result speaks to the sequence, not only the total mass.

When it helps

Two candidate materials have the same mass and a mass result alone cannot tell them apart.
A supplier change, a new lot or an unexpected peak needs a closer look at the sequence.
A specification or customer asks for sequence evidence beyond routine identity.

Limits

Coverage depends on the peptide and the digestion. Very short peptides may give few useful fragments, and full coverage is not guaranteed.
Mapping provides sequence-level evidence for the fragments measured. Purity and quantity require separate tests.
Locating a modification within the sequence is possible only where the fragments allow it. We tell you what the data support.
We need the expected sequence, and a reference material when you have one.

What to send

The peptide, its expected sequence and any modifications, and the question you need answered. We confirm scope and price before you ship.

Price and timing

Quoted per project.

Questions

Questions about a sample or a method, call 360-967-7010 or email [email protected].