In addition to the amino acids listed above, custom amino acids dictionary can be defined.
The custom_aminoacids.dict file is stored in the .chemaxon directory (UNIX) or the user's chemaxon directory using MS Windows.
The usual format of the dictionary file is:
molName=L-Alanine Ala A [CX4H3][C@HX4H1]([NX3])C=O |wD:1.1,(3.85,-1.33,;2.31,-1.33,;1.54,-2.67,;1.54,,;)| 3 4
molName=L-Cysteine Cys C [NX3][C@@HH1]([CH2][SH1])C=O |wD:1.0,(1.54,-2.67,;2.31,-1.33,;3.85,-1.33,;4.62,-2.67,;1.54,,;)| 1 5 4
where the corresponding columns are:
not an obligatory field (introduced in Marvin 6.2)
long (three-letters code) abbreviation
A capital letter followed by two small ones
|short (one-letter code) abbreviation||X and some characters will follow this character between parentheses.|
Allowed characters are the letters of the alphabet, numbers and the dash character.
molName=Sarcosine Sar X(Sar) ....
|SMARTS representation of the amino acid fragment without terminal OH|
Note the SMARTS strings representing amino acid fragments are denoting the hydrogens and sometimes the connection numbers to avoid ambiguity.
For example if only the C[C@H](N)C=O string is used for L-alanine in the first example, this would match for many other amino acids as well as some of them are "containing" this string as a substructure.
No query bonds allowed.
|coordinates of the structure|
Molecular coordinates are needed for cleaning. If they are missing, Ctrl+2 creates the coordinates for the structure.
Coordinates can be generated by Molconvert using:
|the number of the backbone nitrogen in the SMARTS string||3 for Ala in the first example|
|the number of the C terminal carbon||4 for Ala in the first example|
|the number for other attachment point if needed||S for L-cysteine in the second example|
The name and the coordinates are not obligatory fields.
The columns should be separated by tab characters.
To describe an aromatic custom amino acid both the aromatic and the Kekule form should be in the custom_aminoacids.dict file with the same short and long names.