nucleotide_dihedral_side_chain

biotite.structure.nucleotide_dihedral_side_chain(atoms: AtomArray[N] | AtomArrayStack[M, N]) → ndarray[tuple[N], dtype[floating]] | ndarray[tuple[M, N], dtype[floating]]

Measure the glycosidic \(\chi\) dihedral angle of nucleotide residues.

Parameters:

atomsAtomArray or AtomArrayStack

The nucleic acid structure to measure the glycosidic dihedral angles for.

Returns:

chindarray, shape=(m, n) or shape=(n,), dtype=float

An array containing the \(\chi\) angle for every residue. Residues that are not nucleotides or lack the required atoms are filled with \(NaN\) values.

Notes

The \(\chi\) angle is defined between the sugar and the base:

• Purines (e.g. A, G): O4' - C1' - N9 - C4

• Pyrimidines (e.g. C, U, T): O4' - C1' - N1 - C2

The base type is inferred from the presence of the N9 atom, so modified nucleotides are handled as long as they use the canonical glycosidic linkage.