In a parallel arrangement, all of the N-termini of successive strands are oriented in the same direction; this orientation is slightly less stable because it introduces nonplanarity in the inter-strand hydrogen bonding pattern.
1XYB is a Xylose Isomerase, involved in the catalysis of Xylose to Xylulose
1IYE is a transferase that is involved in the catalysis of the biochemical reaction of leucine + oxolutarae --> 4-methyl,2-oxopentanoate + glutamate