Sunday, December 28, 2008

Amylase is an enzyme which breaks starch down into sugar. Human saliva contains Amylase. Foods that contain much starch but little sugar, such as potato and rice, taste slightly sweet, because when they are chewed, amylase turns some of their starch into sugar in the mouth. The pancreas also secretes amylase (alpha amylase) to break down dietary starch into di- and trisaccharides which are converted by other enzymes to glucose to supply the body with energy. Plants and some bacteria also produce amylase. As amylase was the first enzyme to be discovered and isolated by Anselme Payen in 1833. Specific amylase proteins are designated by different Greek letters. All amylases are glycoside hydrolases and act on α-1,4-glycosidic bonds.

The α-amylases are calcium metalloenzymes, which are completely unable to function in the absence of calcium. By acting at random locations along the starch chain, α-amylase breaks down long-chain carbohydrates, ultimately yielding maltotriose and maltose from amylose, or maltose, glucose and "limit dextrin" from amylopectin. Because it can act anywhere on the substrate, α-amylase tends to be faster-acting than β-amylase. In animals, it is a major digestive enzyme and its optimum pH is 6.7-7.0. In human physiology, both the salivary and pancreatic amylases are α-Amylases, which are also found in plants (barley) , fungi and bacteria (Bacillus).