Department of Chemistry
The University of Arizona

Authored By: Abby L. Parrill and Jacquelyn Gervay
Funded by NSF

Proteins are biological molecules which can catalyze reactions, regulate metabolic functions, and perform many other important roles. Proteins are made up of twenty different subunits which can all be classified as amino(containing and NH2 group) acids ( containing a COOH group). Segments of many proteins tend to adopt a small set of three-dimensional structures.

Neuraminidase (a sample protein) (60K)

Left-Handed Alpha Helix (333K)

If you orient your left thumb along the long axis of a left-handed alpha helix, your fingers should wrap around your thumb in the same manner as the helix does from the base of your thumb to your fingernail. Try to locate the intermolecular attractio ns which stabilize this structure.

Right-Handed Alpha Helix(450K)

If you orient your right thumb along the long axis of a right-handed alpha helix, your fingers should wrap around your thumb in the same manner as the helix does from the base of your thumb to your fingernail.Try to locate the intermolecular attractio ns which stabilize this structure.

Anti-Parallel Beta Sheet(2313K)

A beta-sheet consists of chains going in either the opposite direction (anti-parallel) or the same direction (parallel) which form hydrogen bonds between the chains.

Conversion of Beta Sheet from anti-parallel to parallel(450K)

This movie converts a small segment of the anti-parallel beta sheet from the previous movie into a parallel beta sheet. Try to see if you can identify a difference in the intermolecular attractions which might make the anti-parallel beta sheet more c ommon in biological systems.