Original sentence: In proteins, the secondary structure is defined by the patterns of hydrogen bonds between backbone amide and carboxyl groups.Secondary structure can be formally defined by the hydrogen bonds of the biopolymer, as observed in an atomic-resolution structure.The hydrogen bonding patterns may be significantly distorted, which makes an automatic determination of secondary structure   difficult.The secondary structure may be also defined based on the regular pattern of  backbone dihedral angles in a particular region of the Ramachandran plot; thus, a segment of residues with such dihedral angles may be called a helix, regardless of whether it has the correct hydrogen bonds.The secondary structure may be also provided by crystallographers in the corresponding PDB file
Edited sentence: For example, residues in protein helices generally.In proteins, the secondary structure is defined by patterns of hydrogen bonds between backbone amide and carboxyl groups (sidechain-mainchain and sidechain-sidechain hydrogen bonds are irrelevant), where the DSSP definition of a hydrogen bond is used.Least formally, structural biologists.Many other less formal definitions have been proposed, often applying concepts from the.Secondary structure is formally defined by the hydrogen bonds of the biopolymer, as observed in an atomic-resolution structure.The hydrogen bonding is correlated with other structural features, however, which has given rise to.adopt backbone dihedral angles in a particular region of the Ramachandran plot; thus, a segment.differential geometry of curves, such as curvature and torsion.hydrogen bonds.less formal definitions of secondary structure.of residues with such dihedral angles is often called a "helix", regardless of whether it has the correct.solving a new atomic-resolution structure will sometimes assign its secondary structure "by eye" and record.their assignments in the corresponding PDB file