Chymosin (or
rennin, not to be confused with
reninRenin , also known as Angiotensinogenase, is a circumsized enzyme that participates in the body's renin-angiotensin system that mediates extracellular volume , and arterial vasoconstriction...
, a kidney hormone) is an aspartic acid protease
enzymeEnzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at...
found in
rennetRennet is a natural complex of enzymes produced in any mammalian stomach to digest the mother's milk, and is often used in the production of cheese. Rennet contains many enzymes, including a proteolytic enzyme that coagulates the milk, causing it to separate into solids and liquid...
. It is produced by the cow, in the lining of the
abomasumThe abomasum, also known as the maw, and the rennet-bag, and the read, is the fourth and final stomach compartment in ruminants. It secretes rennet, an ingredient used in cheese creation....
(its fourth stomach). Bovine chymosin is produced nowadays recombinantly in
E.coli,
Aspergillus niger var awamoriAspergillus niger is a fungus and one of the most common species of the genus Aspergillus. It causes a disease called black mold on certain fruits and vegetables such as grapes, onions, and peanuts, and is a common contaminant of food...
, and
K.lactis as alternative resource to the one from the cows. The gene is found in humans (on chromosome 1), but it is not in a functioning form.
Chymosin (or
rennin, not to be confused with
reninRenin , also known as Angiotensinogenase, is a circumsized enzyme that participates in the body's renin-angiotensin system that mediates extracellular volume , and arterial vasoconstriction...
, a kidney hormone) is an aspartic acid protease
enzymeEnzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at...
found in
rennetRennet is a natural complex of enzymes produced in any mammalian stomach to digest the mother's milk, and is often used in the production of cheese. Rennet contains many enzymes, including a proteolytic enzyme that coagulates the milk, causing it to separate into solids and liquid...
. It is produced by the cow, in the lining of the
abomasumThe abomasum, also known as the maw, and the rennet-bag, and the read, is the fourth and final stomach compartment in ruminants. It secretes rennet, an ingredient used in cheese creation....
(its fourth stomach). Bovine chymosin is produced nowadays recombinantly in
E.coli,
Aspergillus niger var awamoriAspergillus niger is a fungus and one of the most common species of the genus Aspergillus. It causes a disease called black mold on certain fruits and vegetables such as grapes, onions, and peanuts, and is a common contaminant of food...
, and
K.lactis as alternative resource to the one from the cows. The gene is found in humans (on chromosome 1), but it is not in a functioning form. Rennin is produced by gastric chief cells in infants to curdle the milk they ingest, allowing a longer residence in the bowels and better absorption.
Enzymatic reaction
It causes
cleavageCleavage in general refers to a division or separation of form. Its usage is heavily dependent on cultural context, where it may refer to:*Partial exposure of part of the body:...
of a specific linkage, the
peptide bondA peptide bond is a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amine group of the other molecule, thereby releasing a molecule of water . This is a dehydration synthesis reaction, and usually occursbetween amino acids...
between
phenylalaninePhenylalanine is an α-amino acid with the formula HO
2CCHCH
2C
6H
5. This essential amino acid is classified as nonpolar because of the hydrophobic nature of the benzyl side chain. The codons for
L-phenylalanine are UUU and UUC...
and
methionineMethionine is an α-amino acid with the chemical formula HO
2CCHCH
2CH
2SCH
3. This essential amino acid is classified as nonpolar.-Function:...
in the
K-caseinK-Casein is a mammalian milk protein involved in a number of important physiological processes. In the gut, the ingested protein is split into an insoluble peptide and a soluble hydrophilic glycopeptide...
. If this reaction applies to milk, the specific linkage between the hydrophobic (para-casein) and hydrophilic (acidic
glycopeptideGlycopeptides are peptides that contain carbohydrate moieties covalently attached to the side chains of the amino acid residues that constitute the peptide. Over the past few decades it has been recognised that glycans on cell surface and those bound to proteins play a critical role in biology...
) group of
caseinCasein is the predominant phosphoprotein that accounts for nearly 80% of proteins in cow milk and cheese. Milk-clotting proteases act on the soluble portion of the caseins, K-Casein, thus originating an unstable micellar state that results in clot formation. When coagulated with rennin, casein is...
inside milk would be broken, since they are joined by phenylalanine and methionine. The hydrophobic group would unite together and would form a
3DThree-dimensional space is a geometric model of the physical universe in which we live. The three dimensions are commonly called length, width, and depth , although any three mutually perpendicular directions can serve as the three dimensions....
network to trap the aqueous phase of the milk. The resultant product is calcium phosphocaseinate.
Due to this reaction, rennin is used to bring about the extensive
precipitationPrecipitation is the formation of a solid in a solution during a chemical reaction. When the reaction occurs, the solid formed is called the precipitate, and the liquid remaining above the solid is called the supernate...
and
curdCurds is a dairy product obtained by curdling milk with rennet or an edible acidic substance such as lemon juice or vinegar and then draining off the liquid portion . Milk that has been left to sour will also naturally produce curds, and sour milk cheese is produced this way...
formation in
cheeseCheese is a food consisting of proteins and fat from milk, usually the milk of cows, buffalo, goats, or sheep. It is produced by coagulation of the milk protein casein. Typically, the milk is acidified and addition of the enzyme rennet causes coagulation. The solids are separated and pressed into...
making.