Complex sentence: Xylan is a polysaccharide made from units of the pentose sugar xylose, which is is known for being the first saccharide in multiple biosynthetic pathways of anionic polysaccharides such as heparan sulfate and chondroitin sulfate.
Split into simpler sentences: Xylan is a polysaccharide made from units of the pentose sugar xylose. Xylose is known for being the first saccharide in multiple biosynthetic pathways of anionic polysaccharides such as heparan sulfate and chondroitin sulfate.