What is lipase?

Lipase: A Critical Digestive Enzyme

Lipase is a pancreatic enzyme that catalyzes the hydrolysis of fats (triglycerides) into monoglycerides, glycerol, and free fatty acids in the digestive process, playing an essential role in fat absorption and metabolism. 1

Definition and Structure

• Lipase is a glycoprotein with 420-449 amino acid residues and a molecular weight of 46,000-56,000 for pancreatic lipase and 32,000-39,000 for serum lipase 2
• It contains a catalytic triad with serine as the nucleophilic residue essential for enzymatic activity, distinguishing it from other esterases by the presence of a hydrophobic recognition site 2
• Pancreatic lipase is part of a gene family consisting of 7 mammalian subfamilies, including pancreatic lipase, pancreatic lipase-related proteins, hepatic lipase, lipoprotein lipase, endothelial lipase, and phosphatidylserine phospholipase A1 3

Sources and Distribution

• Lipase is primarily produced by the pancreas but is also found in the intestines and various other tissues 2
• The concentration gradient between pancreatic tissue and serum lipase is approximately 20,000-fold 2
• In addition to pancreatic lipase, other important lipases in mammals include carboxyl ester lipase and gastric lipase 3
• Lipase enzymes are ubiquitous in nature, found in humans, animals, plants, fungi, and microorganisms 4

Function in Digestion

• Pancreatic lipase is secreted by the pancreas in response to food intake and is a key enzyme for fat digestion in the small intestine 5
• It works in conjunction with colipase (a water-soluble, heat-stable protein), bile salts, and calcium to efficiently hydrolyze dietary fats 2
• Human pancreatic lipase is less stable than other pancreatic enzymes against acid denaturation in the duodenum and is rapidly destroyed by pancreatic proteases during small intestinal transit, making lipid digestion vulnerable in pathological conditions 5
• Lipase activity is optimal at pH between 7.5 and 10.0, depending on reaction conditions 2

Clinical Significance

• Serum lipase measurement is considered the "gold standard" for diagnosing acute pancreatitis, with higher sensitivity and specificity compared to amylase 5
• In acute pancreatitis, serum lipase rises within 4-8 hours, peaks at 24 hours, and remains elevated for 8-14 days, providing a longer diagnostic window than amylase 5
• Lipase determinations in pancreatitis are superior to amylase determinations for diagnostic purposes 2
• Normal or low lipase levels in patients with chronic pancreatitis may occur due to destruction of pancreatic tissue 6

Therapeutic Applications

• Pancreatic enzyme replacement therapy (PERT) containing lipase is used to treat exocrine pancreatic insufficiency 5
• PERT products are labeled based on their USP lipase content and include mixtures of lipase, amylase, and proteases 5, 1
• The recommended initial treatment for adults with pancreatic insufficiency is at least 40,000 USP units of lipase during each meal and half that amount with snacks 5
• Dosage should be adjusted based on meal size and fat content to ensure adequate digestion of lipids 5

Industrial Applications

• Lipases have extensive industrial applications in fat and oil processing, food industry, detergents, pulp and paper industry, environmental management, biosensors, and cosmetics 4
• Commercially, microbial lipases are most widely used due to their stability and versatility 4

Safety Considerations with Therapeutic Use

• High doses of pancreatic enzyme products containing lipase (exceeding 6,000 lipase units/kg/meal) have been associated with fibrosing colonopathy, particularly in pediatric patients with cystic fibrosis 1
• Crushing or chewing pancrelipase capsules can disrupt the protective enteric coating, leading to early enzyme release, oral mucosa irritation, and loss of enzyme activity 1

Lipase's critical role in fat digestion makes it an essential enzyme for proper nutrition and metabolism, while its measurement serves as a valuable diagnostic tool for pancreatic disorders.