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# General information

One calls lipase a Enzyme able to carry out the hydrolysis of triglyceride out of glycerol and fatty-acids (Lipolyse). They intervene at the time of the metabolism of the Triglycérides. (" ciseau" molecular). Lipases are proteins. It are contained in many being alive, energy of the virus (where they are coded there) to the complex beings (mammalian). For example at the newborn, gastric lipase has a specific action on a particular variety of triglyceride (with average chain) which is one of the components of the mother's milk. Thus lipase makes it possible to digest triglycerides and thus to ensure a normal nutrition in lipid. Gastric lipase decreases with the age.

The pancreatic Lipase intervenes, at the man, in the Digestion of greases.

N.B. : These Fatty-acids is in particular at the origin of the Goût Acide of the badly preserved Beurre.

# Structure

Whereas there exists in nature a whole panel of lipase, the majority of enter they are built on folds alpha/beta hydrolase and use a mechanism close to that employed by the Chymotrypsine. This mechanism of hydrolysis implies serine like nucleophilic, of the hystidine and an acid (generally of the aspartic acid).

# Applications

Lipases have an activity of hydrolysis of esters. In the presence of water, the esters trigyceridic are transformed into fatty-acid via the reaction:

R is a chain alkyl, saturated or not (the famous unsaturated fatty-acids of it result). In certain cases: $\ rm R=R_1 \ or \ R=R_2 \ or \ R_1=R_2 \ or \ still \ R=R_1=R_2$.

But they have, like all the enzymes, of the needs very constraining:

• of temperature

• of pH
• of water content of the medium
• of the type of substrate
• of the polarity of solvent (so in organic medium)

They can thus be utlized in standard organic chemistry to hydrolize esters on molecules " sensibles". Sometimes they are used to esterify, it is then necessary to eliminate water from the medium to move the balance of Estérification.

The application of the Hydrolyze (or digestion of lipids) to the field of cleaning (crockery, tiling, detergent, etc) is thus very current.

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