amylase(redirected from A-amylase)
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Related to A-amylase: Amyloglucosidase, glucoamylase, Salivary amylase
amylase/am·y·lase/ (am´ĭ-lās) an enzyme that catalyzes the hydrolysis of starch into simpler compounds. The α-a's occur in animals and include pancreatic and salivary amylase; the β-a's occur in higher plants.
amylaseAn enzyme synthesised in the pancreas and salivary glands and secreted in the GI tract which digests starch and glycogen. It is measured in patients with suspected pancreatitis: serum and urine levels peak 4–8 hours after onset of acute pancreatitis, and normalise within 48–72 hours. Parotitis due to mumps or radiation therapy also increases serum amylase; cases of increased serum amylase without obvious pancreatitis or parotitis require quantification of amylase isoenzymes.
Amylase increased in
Acute pancreatitis; obstruction of common bile duct, pancreatic duct or ampulla of Vater; pancreatic injury from perforated peptic ulcer; pancreatic cancer; acute salivary gland disease.
Amylase reduced in
Chronic pancreatitis, pancreatic cancer, cirrhosis, hepatitis, eclampsia.
amylaseClinical chemistry An enzyme synthesized in the pancreas and salivary glands and secreted in the GI tract, which digests starch and glycogen; amylase is measured in Pts with suspected pancreatitis; serum and urine levels peak 4-8 hrs after onset of acute pancreatitis, and normalize within 48-72 hrs; parotitis due to mumps or radiation therapy also ↑ serum amylase; in cases of ↑ serum amylase without pancreatitis or parotitis, requires quantification of amylase isoenzymes Ref range Varies by laboratory; 25-90 U/L, serum; 4-30 U/2 hrs, urine; amylase is ↑ in acute pancreatitis, obstruction of common bile duct, pancreatic duct or ampule of Vater, pancreatic injury from perforated peptic ulcer, acute salivary gland disease; amylase is ↓ in chronic pancreatitis, pancreatic CA, cirrhosis, hepatitis, eclampsia. See Macroamylase.
amylaseAn ENZYME that converts starch to simpler carbohydrates such as disaccharides and small polysaccharides.
amylasea digestive enzyme which enables starch to be split by hydrolysis into smaller subunits of MALTOSE, usually in alkaline conditions (see Fig. 33 ).
Amylases are found in the saliva of most mammals (and were previously called ptyalin). Their functioning is limited to the brief time that food remains in the mouth. Once food is swallowed, the acid stomach conditions prevent further amylase activity. The principal location of starch digestion is in the duodenum, where pancreatic amylase is poured into the gut lumen from the pancreas as part of the pancreatic juice; pancreatic amylase has a greater digestive efficiency than salivary amylase. Amylases are common in plants, particularly in association with the starch stores of seeds and underground perennating organs such as rhizomes, tubers and taproots. Amylases are also produced by MICROORGANISMS such as BACILLUS, STREPTOMYCES and the fungus Aspergillus, and are used in the food industry.