How do α-1,4 linkages in amylose affect its structure?

The presence of α-1,4 linkages in amylose leads to the formation of a linear, unbranched chain of glucose units. This type of linkage is characterized by the connection of the hydroxyl group on the first carbon of one glucose molecule to the fourth carbon of another glucose molecule. Because of this linear arrangement, amylose does not have branches, which distinguishes it from other polysaccharides like amylopectin that contain branches due to α-1,6 linkages.

This unbranched structure allows amylose to adopt a relatively simple helical conformation, which is crucial for its role in storage polysaccharides. The linearity promotes tight packing of the chains when amylose is in a solid form, aiding in its storage function while also affecting solubility and the way it interacts with iodine, which can form inclusion complexes with amylose, resulting in a characteristic blue color.

In summary, the α-1,4 linkages in amylose are instrumental in creating a linear, unbranched polysaccharide, which significantly impacts its physical properties and functionality in biological systems.