# OESecondaryStructure¶

This namespace contains the following constants used as options to OEHasSecondaryStructure and as return values from OEGetSecondaryStructureType. These constants represent sets of bits, and in some cases can be OR’ed together, for example, to designate left-handed alpha helix.

Unassigned

This indicates secondary structure which is unassigned or unknown.

Helix

This indicates any type of helix.

Helix310

This indicates a 3-10 helix.

HelixAlpha

This indicates an alpha helix.

HelixPi

This indicates a pi helix.

Turn

This indicates any type of turn.

Turn3

This indicates a 3-residue turn.

Turn4

This indicates a 4-residue turn.

Turn5

This indicates a 5-residue turn.

Sheet

This indicates a beta sheet.

StrandSense

This bit indicates a strand that is antiparallel to an adjacent strand in a beta sheet. Since strands can be simultaneously parallel and antiparallel to other strands in a sheet, this isn’t an absolute indicator of a strand’s direction. It is useful in some visualization programs to visually illustrate antiparallel character of beta sheets.

HelixLeft

This bit indicates left-handedness of a helix. For example, a left-handed alpha helix would have a value of HelixAlpha | HelixLeft.

Any

This will match any assigned values for secondary structure when used as an option to OEHasSecondaryStructure.