The α‑amylases (1,4‑α‑D‑glucanohydrolases, EC 3.2.1.1) catalyze the hydrolytic degradation of polymeric carbohydrates such as amylose, amylopectin and glycogen by cleaving 1,4‑α‑glucosidic bonds. In polysaccharides and oligosaccharides, several glycosidic bonds are hydrolyzed simultaneously. Maltotriose, the smallest such unit, is converted into maltose and glucose, albeit very slowly.
Two types of α‑amylases can be distinguished, the pancreatic type (P‑type) and the salivary type (S‑type). Whereas the P‑type can be attributed almost exclusively to the pancreas and is therefore organ - specific, the S‑type can originate from a number of sites. As well as appearing in the salivary glands it can also be found in tears, sweat, human milk, amniotic fluid, the lungs, testes and the epithelium of the fallopian tube. Because of the sparsity of specific clinical symptoms of pancreatic diseases, enzymatic determinations are of considerable importance in pancreas diagnostics. The determination of pancreas - specific α‑amylase instead of total α‑amylase is of advantage here. The determination of pancreatic α‑amylase is suitable for the diagnosis and monitoring of acute pancreatitis and acute attacks during chronic pancreatitis. In terms of clinical sensitivity and specificity, the diagnostic value of pancreatic α‑amylase is comparable to that of lipase, the generally recognized pancreas - specific enzyme. The sensitivity of pancreatic α‑amylase is 38 % higher than that of total α‑amylase in the diagnosis of acute pancreatitis when - as commonly used - three times the upper normal limit is taken as the criterion.