Protein FASTA — Ambiguity Codes X, B and Z (.fasta)
Three synthetic protein sequences that begin with methionine and include the X, B and Z ambiguity codes, which are legal IUPAC residues rather than errors. A validator restricted to the twenty standard amino acids rejects all three files.
>NXP001 synthetic protein, contains X B Z ambiguity codes
MFPHWMVITYAVNGYHVGKYQLGSGLGIIENMATCIQHRMPILWEVRSSEKSHYCIQNYD
XBZTIFDHMVKCNNKMLVNEGYTYVRDTKW
>NXP002 synthetic protein, contains X B Z ambiguity codes
MWYANKCSETRWGSQTIMCGVYCAGHIRADGKLVQVDWQWTYHCYLDELTTLNYRPLRCY
XBZAVPKADYADISKWTNVHQFFDRMDKNH
>NXP003 synthetic protein, contains X B Z ambiguity codes
MDEFFGMVNNFHMMQIGRTYSLGCIHAGDFHDRLDRARRRREQTMFMWQGTQGDWSLHFN
XBZHLSNSTQWSWKGSRQANRTHHQAHVKH
Specifications
- Records
- 3
- Sequence Length
- 90
- Alphabet
- 20 amino acids plus X, B, Z
- Ambiguity Codes
- X (any), B (Asp or Asn), Z (Glu or Gln)
- Starts With Methionine
- true
- Seed
- 20260850
Testing contract
Expected to pass- Scenario
- Parse the records and validate every residue against the full IUPAC amino-acid alphabet including ambiguity codes.
- Expected result
- Three sequences validate with X, B and Z accepted as legal residues at positions 61 to 63, and a strict twenty-letter validator rejects each record at position 61.
What is a .fasta file?
FASTA is the plain-text format for biological sequences. Each record begins with a `>` header line carrying an identifier and free-form description, followed by the sequence itself wrapped over as many lines as needed using IUPAC single-letter codes for nucleotides or amino acids. It records no quality or alignment information, which is what keeps it universal.
How to use this file
Use an example .fasta file to test sequence parsers and pipeline entry points, checking multi-record splitting, tolerance of varying line widths and blank lines, correct handling of ambiguity codes, and that description text after the first whitespace is kept separate from the identifier.
How to use this file for testing
“Protein FASTA — Ambiguity Codes X, B and Z (.fasta)” is a deterministic Novus Examples fixture for Scientific data, Editor testing, Error handling. Citation catalogs (BibTeX, RIS), chemistry structures (MDL Molfile, PDB), and gridded binary data (NetCDF, FITS) — for testing reference managers, molecule viewers, and scientific-data loaders.
Documented properties for this file: seed 20260850 · 3 records. Compare results against paired or grouped companions on this page when present (clean↔damaged, searchable↔scanned, or format twins) so scores stay reproducible across runs.
Download the file once, keep the path stable in CI or local scripts, and treat the spec table as the contract: dimensions, seeds, field lists, and roles are intentional. Corrupt or invalid samples are labelled as such — expect parsers to fail loudly rather than silently accept them.
Scientific fixtures are small, valid, and fully synthetic — no real organism, patient, sample, or observation. Point your parser or loader at the file and check it reads the documented records, variables, or headers; binary formats ship a readable twin or metadata listing for comparison.
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