Amylase: Dual Localization in Saliva and Pancreas for Carbohydrate Digestion

α-Amylase is the enzyme secreted by both salivary glands (salivary amylase, ptyalin) and the pancreas (pancreatic amylase) to hydrolyze α-1,4-glycosidic bonds in starch.

Salivary Amylase

• Gene: AMY1 (high copy number variation → population differences).
• Initiates digestion in mouth; inactivated by gastric acid (pH <4).
• Contributes ~10–30% of total starch hydrolysis.

Pancreatic Amylase

• Gene: AMY2A/2B.
• Secreted into duodenum; active at pH 6.7–7.0.
• Major contributor: completes starch → maltose, maltotriose, α-limit dextrins.
• Brush border enzymes (maltase, sucrase-isomaltase) finish to glucose.

Clinical Relevance

• Serum amylase ↑: Acute pancreatitis (3× ULN), salivary gland disease, macroamylasemia, renal failure, perforated ulcer.
• Urinary amylase: More specific for pancreatic origin.
• AMY1 copy number correlates with obesity risk (starch metabolism efficiency).