MassSpeculate | Opilio

1. Protein sequence

Sequence, FASTA, or copied text

0 residuesParent residue sum: -

Mass convention

MassSpeculate now follows your requested convention: candidate masses are residue sums plus selected cysteine/PTM deltas. It does not add H2O to peptide/protein chains.

2. Experimental intact masses

Neutral masses, one per line or separated by commas / spaces

Tolerance (Da)

Residue mass type

Min product length

Max hits / mass

Show near misses <= Da

3. Proteolysis model

Terminal trimming / contiguous fragments

Internal excision: one contiguous loop/gap removed

Min retained arm length

Max internal gap length

Candidate cap

Internal excision reports products as left arm + right arm with a gap such as 1-45 + 63-137.

4. Cysteine state

For iodoacetamide, MassSpeculate uses carbamidomethylation (+57.021464 mono / +57.0513 average) per Cys. S-methyl Cys is separate (+14.01565 mono / +14.02658 average). Cysteinylation (mixed disulfide with free cysteine, e.g. from expression media) is modeled as +119.00410 mono / +119.1432 average per modified Cys.

5. PTM / delta-mass explanations

Search ABRF delta-mass list

Max ABRF deltas per candidate

PTM name filter, optional

Embedded ABRF table

average delta-mass entries are embedded from the ABRF Delta Mass page. ABRF describes the page as a database of protein post-translational modifications and labels this table “Average Masses.”

No analysis run yet.

Results will appear here.

Candidate matches

Notes / interpretation