molsysmt.element.group.amino_acid.get_1_letter_code_from_name

molsysmt.element.group.amino_acid.get_1_letter_code_from_name(name)

Return the one-letter IUPAC code for an amino acid given its three-letter or variant name.

The function first maps the input name to a canonical three-letter code via name_to_type, then converts that code to the standard single-letter representation using the IUPAC amino-acid alphabet.

Parameters:

name (str) – Residue name as stored in the topology (e.g. 'ALA', 'HID', 'NALA'). Variant names (protonation states, N/C-terminal prefixes) are resolved to their canonical type before the lookup.

Returns:

Single IUPAC letter code for the amino acid (e.g. 'A' for alanine, 'R' for arginine). Ambiguity codes ('B', 'Z', 'X', 'J') are returned for the corresponding degenerate residue types.

Return type:

str

Raises:

KeyError – Raised if name is not present in the name_to_type mapping or if the resolved canonical name is not present in the aa3_to_aa1 table.

Notes

The complete mapping from three-letter codes to one-letter codes follows the IUPAC-IUB nomenclature and includes the 20 standard amino acids as well as selenocysteine ('SEC' → 'U'), pyrrolysine ('PYL' → 'O'), and the standard ambiguity codes.

Added in version 1.0.0.