## Sequence.residues — list of all residues in the sequence

> This is a standard Python list of all the residues in the sequence. This can be used to query individual residue properties (e.g. amino acid type) or to specify residues for use in restraints, etc.

> Residues can be individually accessed in two ways:

- A string of the form 'RESIDUE_#[:CHAIN_ID]', where RESIDUE_# is a five character residue number (four characters for the number itself, plus one for an optional insertion code) as it occurs in the PDB file of a model, and the optional CHAIN_ID is the single character chain id as it occurs in the PDB file. For example, if `'s'` is a `Sequence` object, PDB residue '10' in chain 'A' is given by `'s.residues['10:A']'`; if the chain has no chain id, `'s.residues['10']'` would be sufficient. Note that the quotes are required to force the use of PDB numbers.

- By numeric index, starting from zero, in standard Python fashion. For example, if `'s'` is a `Sequence` object, `'s.residues[1]'` is the second residue. Contrast with `'s.residues['1']'` above, which returns the residue with PDB number '1'.

> See Section 6.20 for more information about `Residue` objects. See also model.residue_range(), for getting a contiguous range of residues in a model.