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Amino acid constellation 2

Documentation and references are available.
This constellation is for 16 AAs (Asx, Glx, Ser, His, Gly, Thr, Ala, Pro, Tyr, Arg, Val, Met, Ile, Leu, Phe, Lys), does not consider Cys and Trp, and calculates Asn and Asp together as Asx, and Glu and Gln together as Glx.

Fill in the experimentally determined AA composition for the unknown protein. You may give a name to your protein, and also specify pI and Mw values.

The OS or OC (Organism Species or Organism Classification) field allows you to specify terms to limit the search to a range of organisms or to a specific organism (species). A Swiss-Prot / TrEMBL entry will only be returned, if all the given terms appear in either the OS or OC lines of that entry. If in doubt, please consult the Swiss-Prot list of species.

Scan in Swiss-Prot can be restricted by the use of a keyword. This should be a keyword in the Swiss-Prot KW lines. If in doubt, consult the Swiss-Prot list of keywords.

When searching in Swiss-Prot, AACompIdent removes signal sequences and / or propeptides (as documented in the Swiss-Prot feature table (FT lines)) before computing AA composition, pI and Mw for each of the resulting chains.

The annotation in TrEMBL is done automatically; it is incomplete and not always correct. Thus information on TrEMBL FT lines is not used to process TrEMBL proteins into mature chains or peptides (i.e. AA composition, pI and Mw are always computed for the whole sequence), and the use of a keyword is not allowed for searches in TrEMBL.

Additional options are available at the bottom of this page.

The results will be sent back by e-mail.

Please fill out the following form, then press the Run AACompIdent button.

Your e-mail address:

Unknown protein

Name of unknown protein:

pI: within pI range:
Mw (in Daltons, not kD): within Mw range (in percent):

Term from OS or OC lines:

Keyword from KW lines (for search in Swiss-Prot only):

Amino acid composition (in molar percent, ex: 12.50):

Asx:  Glx:  Ser:

His:  Gly:  Thr:

Ala:  Pro:  Tyr:

Arg:  Val:  Met:

Ile:  Leu:  Phe:


Calibration protein

If you have analysed a calibration protein in parallel with unknowns as part of your AA analysis procedure, specify the Swiss-Prot ID name for that protein and enter its experimentally determined AA composition.

Protein ID: (example: ALBU_BOVIN)

Asx:  Glx:  Ser: in molar percent (example: 6.30)

His:  Gly:  Thr:

Ala:  Pro:  Tyr:

Arg:  Val:  Met:

Ile:  Leu:  Phe:


Database(s) on which the scan should be performed:
Swiss-Prot and TrEMBL
To perform the search: or to clear all fields!


Number of proteins to search for:

First, Swiss-Prot / TrEMBL entries for the given species are searched and the most similar ones displayed. Then, all Swiss-Prot / TrEMBL entries are searched. Finally, only the protein entries for which the theoretical pI and Mw lie within the given ranges are searched.

With this option, 40 amino acids of sequence for each protein are printed in the results, instead of the protein description. You may optionally also enter a tag which will be matched with the sequences. 'X' can be used to mean 'any amino acid'.
Tag (up to 6 amino acids):

Search for all possible tag permutations.

Display the N-terminal sequence or the C-terminal sequence or the (internal) area of the protein sequence that matches your tag.