Parallel beta-helix repeat - PbH1

The tertiary structures of pectate lyases and rhamnogalacturonase A show a stack of parallel beta strands that are coiled into a large helix. Each coil of the helix represents a structural repeat that, in some homologues, can be recognised from sequence information alone. Conservation of asparagines might be connected with asparagine-ladders that contribute to the stability of the fold. Proteins containing these repeats most often are enzymes with polysaccharide substrates.