Agent skill
bio-proteomics-peptide-identification
Peptide-spectrum matching and protein identification from MS/MS data. Use when identifying peptides from tandem mass spectra. Covers database searching, spectral library matching, and FDR estimation using target-decoy approaches.
Install this agent skill to your Project
npx add-skill https://github.com/FreedomIntelligence/OpenClaw-Medical-Skills/tree/main/skills/bio-proteomics-peptide-identification
SKILL.md
Version Compatibility
Reference examples tested with: MSnbase 2.28+
Before using code patterns, verify installed versions match. If versions differ:
- Python:
pip show <package>thenhelp(module.function)to check signatures - R:
packageVersion('<pkg>')then?function_nameto verify parameters
If code throws ImportError, AttributeError, or TypeError, introspect the installed package and adapt the example to match the actual API rather than retrying.
Peptide Identification
"Identify peptides from my MS/MS spectra" → Match tandem mass spectra against a protein database to identify peptide sequences, then control false discovery rate using target-decoy competition.
- Python:
pyopenmsfor in-memory database search and PSM handling - CLI:
comet,MSFragger,X!Tandemfor high-throughput database searching - R:
MSnbase::readMSData()for importing search results
Database Search with pyOpenMS
Goal: Identify peptide sequences from tandem mass spectra by matching against a protein database.
Approach: Load a FASTA database, perform in-silico tryptic digestion to generate theoretical peptides, then match experimental spectra against theoretical fragment ion patterns to identify peptide-spectrum matches (PSMs).
from pyopenms import MSExperiment, MzMLFile, FASTAFile, ProteaseDigestion
from pyopenms import ModificationsDB, AASequence
# Load FASTA database
fasta_entries = []
FASTAFile().load('uniprot_human.fasta', fasta_entries)
# In-silico digestion
digestion = ProteaseDigestion()
digestion.setEnzyme('Trypsin')
digestion.setMissedCleavages(2)
peptides = []
for entry in fasta_entries:
seq = AASequence.fromString(entry.sequence)
result = []
digestion.digest(seq, result)
peptides.extend([(entry.identifier, str(p)) for p in result])
Working with Search Results (idXML)
from pyopenms import IdXMLFile, ProteinIdentification, PeptideIdentification
protein_ids = []
peptide_ids = []
IdXMLFile().load('search_results.idXML', protein_ids, peptide_ids)
for pep_id in peptide_ids:
rt = pep_id.getRT()
mz = pep_id.getMZ()
for hit in pep_id.getHits():
sequence = hit.getSequence()
score = hit.getScore()
charge = hit.getCharge()
FDR Estimation (Target-Decoy)
def calculate_fdr(scores, is_decoy, score_threshold):
above_threshold = scores >= score_threshold
n_target = ((~is_decoy) & above_threshold).sum()
n_decoy = (is_decoy & above_threshold).sum()
fdr = n_decoy / n_target if n_target > 0 else 1.0
return fdr
def find_score_at_fdr(scores, is_decoy, target_fdr=0.01):
sorted_scores = np.sort(scores)[::-1]
for threshold in sorted_scores:
fdr = calculate_fdr(scores, is_decoy, threshold)
if fdr <= target_fdr:
return threshold
return sorted_scores[-1]
R: Search Result Processing
library(MSnbase)
# Read mzIdentML results
psms <- readMzIdData('results.mzid')
# Filter to 1% FDR
psms_filtered <- psms[psms$qvalue <= 0.01, ]
# Unique peptides per protein
peptide_counts <- table(psms_filtered$accession)
Spectral Library Search
from pyopenms import SpectraSTSearchAlgorithm, MSExperiment
# Load spectral library
library = MSExperiment()
MzMLFile().load('spectral_library.mzML', library)
# Match query spectra against library
# Returns similarity scores and library matches
Related Skills
- data-import - Load raw MS data before identification
- protein-inference - Group peptides to proteins
- ptm-analysis - Identify modified peptides
Recommended Agent Skills
Expand your agent's capabilities with these related and highly-rated skills.
vcf-annotator
Annotate VCF variants with VEP, ClinVar, gnomAD frequencies, and ancestry-aware context. Generates prioritised variant reports.
chemist-analyst
Analyzes events through chemistry lens using molecular structure, reaction mechanisms, thermodynamics, kinetics, and analytical techniques (spectroscopy, chromatography, mass spectrometry). Provides insights on chemical processes, material properties, reaction pathways, synthesis, and analytical methods. Use when: Chemical reactions, material analysis, synthesis planning, process optimization, environmental chemistry. Evaluates: Molecular structure, reaction mechanisms, yield, selectivity, safety, environmental impact.
bio-alignment-io
Read, write, and convert multiple sequence alignment files using Biopython Bio.AlignIO. Supports Clustal, PHYLIP, Stockholm, FASTA, Nexus, and other alignment formats for phylogenetics and conservation analysis. Use when reading, writing, or converting alignment file formats.
sleep-analyzer
分析睡眠数据、识别睡眠模式、评估睡眠质量,并提供个性化睡眠改善建议。支持与其他健康数据的关联分析。
metabolomics-workbench-database
Access NIH Metabolomics Workbench via REST API (4,200+ studies). Query metabolites, RefMet nomenclature, MS/NMR data, m/z searches, study metadata, for metabolomics and biomarker discovery.
bio-hi-c-analysis-matrix-operations
Balance, normalize, and transform Hi-C contact matrices using cooler and cooltools. Apply iterative correction (ICE), compute expected values, and generate observed/expected matrices. Use when normalizing or transforming Hi-C matrices.
Didn't find tool you were looking for?