Bile salt-dependent lipase (or BSDL), also known as carboxyl ester lipase (or CEL) is an enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 produced by the adult pancreas

Pancreas

The pancreas is a gland organ in the digestive and endocrine system of vertebrates. It is both an endocrine gland producing several important hormones, including insulin, glucagon, and somatostatin, as well as a digestive organ, secreting pancreatic juice containing digestive enzymes that assist...

 and aids in the digestion of fats. Bile salt-stimulated lipase (or BSSL) is an equivalent enzyme found within breast milk

Breast milk

Breast milk, more specifically human milk, is the milk produced by the breasts of a human female for her infant offspring...

. BSDL has been found in the pancreatic secretions of all species in which it has been looked for. BSSL, originally discovered in the milk of humans and various other primate

Primate

A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...

s, has since been found in the milk of many animals including dogs, cats, rats, and rabbits.

Enzymatic activity

More than 95% of the fat present in human milk and in infant formulas is in the form of triacylglycerols (TG).
In adults, TGs are thought to be broken down or hydrolyzed

Hydrolysis

Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...

 mainly by the colipase-dependent lipase enzyme. In the newborn, CDL activity in the duodenum

Duodenum

The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms anterior intestine or proximal intestine may be used instead of duodenum...

 is lower than in adults.

Both BSDL and BSSL have a broad substrate specificity and, like CDL, are capable of hydrolyzing triacylglycerides (in addition to phospholipid

Phospholipid

Phospholipids are a class of lipids that are a major component of all cell membranes as they can form lipid bilayers. Most phospholipids contain a diglyceride, a phosphate group, and a simple organic molecule such as choline; one exception to this rule is sphingomyelin, which is derived from...

s, ester

Ester

Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...

s of cholesterol

Cholesterol

Cholesterol is a complex isoprenoid. Specifically, it is a waxy steroid of fat that is produced in the liver or intestines. It is used to produce hormones and cell membranes and is transported in the blood plasma of all mammals. It is an essential structural component of mammalian cell membranes...

, and lipid soluble vitamins). BSDL production in the newborn pancreas is quite low when compared with production in the mammary gland

Mammary gland

A mammary gland is an organ in mammals that produces milk to feed young offspring. Mammals get their name from the word "mammary". In ruminants such as cows, goats, and deer, the mammary glands are contained in their udders...

or adult pancreas.

However, newborn infants absorb lipids relatively well, considering the low level of CDL and BSDL they produce. This observation has led to the suggestion that BSDL produced by lactating mammary gland and present within milk, may compensate for the low levels of other TG-digesting enzymes and aid newborns in lipid absorption.

Further reading