Triose phosphate isomerase  : β/α barrel
Cartoons view of Triosephosphate isomerase, an 8-stranded beta/alpha barrel protein. The center contains an 8-stranded parallel beta-sheet. Each adjacent pair of beta-strands is connected by an alpha helix, making the outer surface of the protein.

The beta-alpha-beta motif is highlighted: beta strands in blue, alpha helix in cyan. It has right-handed connectivity.

In beta/alpha barrel proteins, the active site is typically formed from the loops at the C-terminal ends of the parallel beta-strands. These are colored yellow, in spacefilling. The substrate DHAP is shown in CPK colors.


Jogl G, Rozovsky S, McDermott AE, Tong L.:
Optimal alignment for enzymatic proton transfer: structure of the Michaelis complex of triosephosphate isomerase at 1.2-A resolution.
Proc Natl Acad Sci U S A. 2003 Jan 7;100(1):50-5. (PubMed)

1ney (PDB)