Pancreatic Lipase: Definition, Structure, Types, Normal Levels, Mechanism, Properties and Relationship to Weight Loss

It is a digestive enzyme secreted by the pancreas that uses hydrolysis to separate fat molecules.

It is secreted by the pancreas and is the primary lipase (enzyme) that hydrolyzes (breaks down) dietary fat molecules in the human digestive system.

Converting triglyceride substrates found in ingested oils into monoglycerides and free fatty acids by breaking hydrogen bonds in the small intestine.

Normally its concentration in serum is very low, but when an excessive increase in lipase levels is observed, the presence of pancreatitis or pancreatic adenocarcinoma can be inferred.

Dietary fats are essential for life and good health.

The efficient absorption of fats from the diet depends on the action of pancreatic lipase.

In recent years, great advances have been made in describing the structure and mechanism of human pancreatic lipase and colipase .

Colipase is another pancreatic protein that interacts with pancreatic lipase and is necessary for lipase activity in the duodenum.

Structure

Lipase is the known three-dimensional structure with the most complex architecture, it presents a canonical structural domain that is formed by eight chains and a protein cofactor.

It is particularly useful in trying to define a common interfacial orientation of all lipases in the absence of experimental data documenting the enzymatic orientation and surface penetration of lipid aggregates and without the need to run molecular dynamics simulations.

A general model for the orientation of lipases at a lipid-water interface can be deduced from the combined structural homologies of pancreatic lipases with other lipases (common α / β-hydrolase fold) on the one hand, and binding domains to lipids on the other hand.

Types of pancreatic lipases

The juices of the pancreas contain several enzymes to perform the digestion of lipids, among which the following stand out:

  • Triacylglycerol hydrolase, which hydrolyzes the bonds of triglyceride molecules.
  • Cholesterol ester hydrolase, which hydrolyzes cholesterol esters.
  • Phospholipase A2, which hydrolyzes phospholipids.

Normal levels of pancreatic lipases

Pancreatic lipase levels are determined through a laboratory test called lipasemia, which is an assessment of lipase levels in blood plasma.

Normal values ​​are below 190 units per liter (U / L).

Mechanism

Bile salts secreted by the liver and stored in the gallbladder are released into the duodenum, where they coat and emulsify large fat droplets into smaller droplets.

Because the droplets are small, their surface area is larger, which allows the lipase to separate the fat more effectively.

The resulting monomers then move peristalsically through the small intestine.

Pancreatic lipase is secreted into the duodenum through the duct system of the pancreas.

The resulting monomers are two free fatty acids and one 2-monoacylglycerol, which then move through peristalsis through the small intestine to be absorbed into the lymphatic system by a specialized container called lactose.

The resulting fatty acids and monoglycerides are incorporated into the bile salts forming micelles.

These micelles are absorbed into the brush border of the small intestine and eventually enter the bloodstream as chylomicrons.

Lipase requires a high pH for its activation among food enzymes.

That is why fats are the most difficult to digest.

Pancreatic lipase, unlike some pancreatic enzymes that are activated by proteolytic cleavage (eg, trypsinogen), is secreted in its final form.

However, it only becomes effective in the presence of colipase in the duodenum in the presence of bile acids provided by the liver.

In humans, pancreatic lipase is encoded by the PNLIP gene.

Biochemical properties

Pancreatic lipase is a water-soluble lipolytic enzyme that hydrolyzes the ester bonds of triglycerides.

The enzyme is a 449 amino acid single chain glycoprotein.

It is part of an Asp-His-Ser triad that is chemically analogous to, but structurally different from, that of the serine proteases.

Inhibition of pancreatic lipase activity

Natural products that inhibit pancreatic lipase activity can suppress dietary fat absorption from the small intestine.

These include peptides and basic proteins, which destroy the lipid emulsion by binding to bile salts, thus suppressing the activity of pancreatic lipase.

Recently, protamine, purothionin, and histone, which belong to a class of basic proteins, were reported to inhibit lipase.

These substances inhibit lipase on substrates containing phosphatidylcholine.

From these results, it was suggested that these compounds inhibit lipase activity by interaction with triolein and phosphatidylcholine.

Pancreatic lipase and weight loss

People who are concerned about losing weight may be more than familiar with this enzyme and what it does.

This is because several products have emerged that have the ability to block its activity to inhibit fat absorption.

In fact, there are prescription drugs that prevent up to 30% of dietary fats, including triglycerides, from being absorbed through the intestines.

This results in a reduction in total calorie intake and subsequently in weight loss.

Research on lipases

Researchers have discovered other unique properties of pancreatic lipase by studying hibernating squirrels.

While this enzyme is normally found in the intestines, it is found in high concentration in the hearts of these animals, but only from late fall to early spring.

Apparently, after completing the job of digesting dietary fat for storage during deep sleep, the enzyme settles in the heart to help it function as body temperature and oxygen levels drop dramatically.

What is particularly interesting about this is that most other enzymes become inactive below certain temperatures, while this one retains about 30% of its activity.

Hyperproduction

Excessive production of this enzyme can indicate the presence of certain disorders, especially: inflammation of the pancreas or pancreatitis.

Bowel obstruction, peptic ulcers, or kidney disease are also a temporary side effect of some medications, such as:

  • Beethane.
  • Birth control pills.
  • Cholinergic medications
  • Codeine.
  • Indomethacin.
  • Meperidine.
  • Methacholine.
  • Morphine.
  • Thiazide diuretics.

Hypoproduction

Decreased levels may suggest that some cells in the pancreas are irreversibly damaged.

Pancreatic lipase monitoring is also used to help diagnose Crohn’s disease, cystic fibrosis, and celiac disease.

Deficiency

People with lipase deficiency are expected to have a tendency to high cholesterol, high triglycerides, difficulty losing weight, diabetes, or a tendency to glycosuria (sugar in the urine without symptoms of diabetes), which can lead to heart disease .

It is recommended in patients with low lipase levels, a low-fat diet, and vitamin D, E, and K supplements.

People with lipase deficiency have decreased cell permeability, which means that nutrients cannot enter and waste cannot leave the cell.

For example, diabetics are lipase deficient and cannot get glucose into their cells, and waste or unwanted substances cannot get out.

People with hidden viruses who are often diagnosed with “Chronic Fatigue Syndrome” also fall into this category.

Lipase modulates cell permeability so that nutrients can enter and waste can exit.

A common symptom of lipase deficiency is muscle spasms.

This is not the “muscle cramp” (tetany) that results from low-ionized calcium in the blood.

It commonly occurs as trigger point pain in the muscles across the upper shoulders, but can occur in other muscles, such as those in the neck or anywhere in the small or large intestine, including the muscles of the rectal tissues.

People with a “spastic colon” may be deficient in lipase.

Muscle relaxant medications are given to control symptoms.

The condition of vertigo, or labyrinthitis , also called Miereiere’s disease (dizziness made worse by movements such as walking or driving), can be the result of lipase deficiency.

The menopausal condition is often associated with lipase deficiency because the lipase targets the gonadal tissue.