diastase

Diastase is a historical and general term for enzymes that catalyze the breakdown of starch into sugars. In modern biochemistry, the enzymes in this family are usually called amylases, with various forms including alpha-, beta-, and gamma-amylases. Among these, alpha-amylase is the most clinically relevant and is produced by human salivary glands and the pancreas, as well as by many plants and microbes.

Mechanism and substrates: Amylases act on starch, a polymer of glucose. They cleave the alpha-1,4 glycosidic bonds within amylose and amylopectin to generate shorter glucose polymers and maltose; some amylases, such as glucoamylases, can release glucose units more directly. The different types have varying specificities: some act mainly on internal bonds (endoamylases), while others progressively release maltose from chain ends (exodegradative enzymes).

Sources and applications: Natural diastases are produced by humans (saliva and pancreas), plants, and microorganisms. Malt diastase historically referred to amylolytic enzymes derived from barley malt and was important in brewing and digestion research. Industrially, microbial amylases from fungi and bacteria are used in food processing, brewing, paper production, and textile industries, as well as in baking to modify dough properties.

Clinical and historical context: Historically, diastase activity was measured in diastase units and used in diagnosing pancreatic disorders. Contemporary clinical practice more commonly uses measurements of serum amylase activity, with urine tests largely supplanted by serum testing. Elevated amylase can indicate pancreatitis or salivary gland inflammation, while low or normal levels generally provide limited diagnostic value without correlation to symptoms and other tests.