pub const BB_COORDINATES: [[f32; 3]; 3];Expand description
Backbone heavy-atom positions in the canonical local frame.
Cα is at the origin, Cα→C is along +x, and N lies in the x–y plane.
Rows: [N, CA, C]. Shape: [3, 3]. Units: Ångström.
Source: ideal peptide geometry (Engh & Huber, 1991).