pancreatic lipase

Pancreatic lipase is secreted by acinar cells of the exocrine pancreas as part of pancreatic juice, along with amylase, proteases (trypsinogen, chymotrypsinogen), and colipase. It acts at the lipid-water interface of emulsified fat droplets (emulsification aided by bile salts) to hydrolyze triglycerides into 2-monoacylglycerol and free fatty acids, which are then packaged into micelles with bile salts for absorption by enterocytes. Colipase, activated by trypsin, binds to lipase and prevents bile salts from inhibiting its activity, anchoring the enzyme to the lipid droplet surface. Optimal enzyme activity occurs at a slightly alkaline pH, maintained by bicarbonate secretion from pancreatic duct cells (mediated by secretin). Clinically, pancreatic lipase deficiency—seen in chronic pancreatitis, pancreatic cancer, or cystic fibrosis (due to duct obstruction by thick mucus)—leads to malabsorption of fats and fat-soluble vitamins (A, D, E, K), causing steatorrhea (bulky, greasy, foul-smelling stools) and deficiency syndromes (e.g., bleeding diathesis from vitamin K deficiency, osteomalacia from vitamin D deficiency). Serum lipase is also a key diagnostic marker for acute pancreatitis, being more specific than amylase and remaining elevated longer (up to 8-14 days) after an acute attack. Orlistat, an anti-obesity drug, works by inhibiting pancreatic and gastric lipase, reducing fat absorption.