Monohelical

Monohelical is an adjective used in chemistry, biochemistry, and materials science to describe a structure or molecule that contains a single helix or one continuous helical segment along its axis. The term derives from Greek monos (single) and helix (coil). In structural biology, monohelical can describe a polypeptide or protein motif that forms a single uninterrupted alpha-helix, as opposed to polyhelical structures that contain several helices or helical bundles. Such monohelical segments are common building blocks in proteins and can contribute to stability, binding interfaces, or recognition motifs depending on length and side-chain composition. However, many proteins contain multiple helices, so monohelical descriptions are typically applied to isolated helices, short peptides, or segments within a larger structure.

In polymer science and foldamer research, monohelical refers to synthetic molecules that adopt one dominant helical conformation rather than an array of interacting helices. Research aims include controlling handedness, pitch, and diameter to create predictable, uni-axial helical structures for applications in nanotechnology, catalysis, or molecular recognition. The concept contrasts with polyhelical or multihelix systems, which include coiled-coils or helical bundles.

Usage of monohelical is not strictly standardized; it is often descriptive rather than a formal category, and its meaning can depend on the length, context, and methods used to determine structure (such as X-ray crystallography, NMR, or computational modeling).