Pepsin physical properties. Beef pepsin - composition, what is it

It is also pepsin - a substance that is produced by the stomach and serves to break down protein (and is used in the same capacity in cheese making).

Accordingly, pepsin is produced, both for medical and food purposes, from the stomachs of animals.

Beef pepsin is one of two milk-clotting enzymes that are part of rennet, which is produced in the mucous membrane of the fourth part of the stomach of the calf (abomasum).

As it became known, the origin of beef pepsin is an absolute accident. It is known from history that when Arab nomads traveled through hot areas, they carried milk in leather bags made from animal stomachs. The end result is a curd that looks like cheese.

Of course, they could not even think that the function of a milk-clotting enzyme, which turned sour milk into a cheese-like mass, was performed by beef pepsin contained in the walls of leather bags.

And only starting from the 40s of the 20th century, a complex of scientific studies was carried out, which made it possible to understand the mechanism of rennet coagulation of milk.

Conventionally, two main functions of a milk-clotting enzyme can be distinguished: the formation of a milk clot (enzymatic coagulation of milk) and participation in the maturation of cheese and the production of cottage cheese.

The quality of milk clot formation determines its elastic properties, the degree of capture of proteins, fat and mineral components into the clot, the ability to cut, the processes of syneresis and pressing, which ultimately determines the yield of cheese, its moisture content, the intensity and direction of biochemical processes during ripening. that shape the taste of the product.

Thus, at the stage of formation of a milk clot (coagulation of milk), the basis for the quality of cheese is laid.

Beef pepsin (PG) brand preparation contains two enzymes chymosin and bovine pepsin, which are in a natural proportion, characteristic of their content in the mucous membrane of the abomasum of adult cattle.

The drug of this brand is made by extraction. Commercial batches of this drug may contain up to 10% chymosin.

Beef pepsin is produced from the mucous membrane of the abomasum of adult cattle. In the manufacture of PG, there are two stages of purification from insoluble impurities and fat. The amount of insoluble impurities in the finished product is not more than 3.0% by weight.

The technology for the production of milk-clotting enzyme preparations is similar to the production of medical preparations and includes several cyclic components; the process of extraction, salting out, freeze-drying.

The drug has a milk-clotting activity of 100,000 h 120,000 conventional units, the consumption of drugs with this activity in the production of soft cheeses and feta cheese is 2.0 h 2.5 g per 100 l of milk, in the production of cottage cheese 0.25 g per 100 l of milk.

Milk-clotting enzyme beef pepsin is recommended for use without restrictions in the production of soft and pickled cheeses, feta cheese, cottage cheese and fat-free cheese mass.

Beef pepsin is added to cottage cheese to give it softness, tenderness and for easier and more complete absorption of curd protein.

You can buy beef pepsin at a pharmacy, in specialized stores or online stores.

Benefits of Beef Pepsin

Consider the advantage of beef pepsin by comparing it with pork pepsin as an example.

A common property of milk-clotting enzymes is a decrease in the total proteolytic activity at a pH above the optimal level.

One reason for this is the inactivation of enzymes at high pH. The rate of inactivation depends on the type of enzyme.

Thus, beef pepsin begins to inactivate after 20 minutes of exposure only at pH above 6.4, and at pH 7.0 it retains more than a third of its initial activity.

At the same time, porcine pepsin after a 20-minute exposure at pH 6.4 loses more than 50% of its initial activity, and at pH 7.0 it is almost instantly completely inactivated.

To coagulate milk with a pH of 6.6 in 5 minutes, the same mass of beef and pork pepsin is required, and when curdled in 20 minutes, pork pepsin is required 2.5 times more than beef.

The rapid inactivation of porcine pepsin in a slightly acidic environment, such as milk, is its main disadvantage as a milk-clotting enzyme.

Pepsin- the main proteolytic enzyme of gastric juice, belongs to the group of peptide hydrolases. Cleaves proteins mainly to polypeptides, although among the cleavage products there are low molecular weight peptides and amino acids. In some pathological conditions, the activity of pepsin in gastric juice is one of the diagnostic signs. The content of P.'s proenzyme - pepsinogen - in the urine (uropepsin) serves as an additional diagnostic test in the study of the secretory ability of the gastric mucosa. Pepsin It is also used in the food and meat and dairy industry. The molecular weight of pepsin is about 35,000, the isoelectric point is at a pH below 1.0. Pepsin most stable at pH around 5.0-5.5. In a more acidic environment, autolysis of the enzyme occurs; at a pH above 6.0, its rapid and practically irreversible inactivation occurs (pepsin is also inactivated at temperatures above 60 °).

In the gastric juice of humans and higher mammals, along with P., there is gastrixin, an enzyme that has properties similar to pepsin and a homologous structure.

P. is synthesized by the main glandulocytes of the gastric mucosa in the form of an inactive precursor, the pepsinogen proenzyme, which, in the presence of hydrochloric acid of gastric juice, is converted into an active enzyme. In the urine of mammals, incl. a person, pepsinogen is normally detected (level pepsin).

The process of protein digestion in the gastrointestinal tract begins with the action of P. It breaks down almost all proteins of plant and animal origin, with the exception of protamines and keratins. The optimum action of pepsin is at pH 2.0. At a pH of about 5.0, pepsin curdles milk, causing the conversion of caseinogen to casein. P. is able to hydrolyze a number of low molecular weight synthetic peptides and esters, which include aromatic amino acids. The optimum for pepsin hydrolysis of many synthetic substrates is at pH 4.0. Pepsin also catalyzes the transpeptidation reaction (transfer of an amino acid residue from one synthetic substrate to another).

To determine the activity of pepsin, the Anson method is used, which consists in the splitting of denatured hemoglobin, followed by the determination of the amount of tyrosine in the protein-free filtrate. To study P.'s activity in gastric juice and the content of uropepsin in the urine, the Pyatnitsky method is widely used, based on determining the curdling activity of the enzyme.

With a number of diseases of the gastrointestinal tract - chronic gastritis, gastric and duodenal ulcers (see. peptic ulcer), stomach cancer, as well as pernicious anemia, hypochromic anemia (see. Anemia) pepsin secretion is impaired. In this regard, the determination of pepsin in gastric juice, along with hydrochloric acid, has significant diagnostic value. The determination of uropepsin in urine is also used, the content of which is believed to reflect the level of secretory capacity of the gastric mucosa.

Pepsin(Pepsinum), used as a medicine, is obtained from the gastric mucosa of pigs. The drug is a white or cream powder of sweet taste with a specific odor, soluble in water, in 20% ethyl alcohol and insoluble in ether and chloroform.

Usually pepsin has a rather low proteolytic activity: 1 G the drug contains only 5 mg pure enzyme. To ensure the optimal effect of the drug, the reaction of the medium in the stomach should be acidic, and the concentration of free hydrochloric acid should not be lower than 0.15-0.2%.

Pepsin used for replacement therapy for digestive disorders, accompanied by secretory insufficiency of the stomach (achilia, hypoacid and anacid gastritis, dyspepsia, etc.). It should be borne in mind that the main glandulocytes of the gastric mucosa usually secrete endogenous P. in excessive quantities, as well as other digestive enzymes. Therefore, a decrease in the digestive capacity of gastric juice with a decrease in its acidity is often the result of insufficient release of hydrochloric acid, and not a decrease in the activity or intensity of pepsin formation. Thus, in hypoacid conditions, the main thing is to provide optimal conditions for the digestion of gastric contents, and the use of pepsin is of secondary importance. In anacid conditions, when the acid-forming function of the stomach is reduced, it is advisable to use P. in combination with diluted hydrochloric acid.

Pepsin appoint inside: adults 0.2-0.5 G for reception 2-3 times a day before meals or during meals in powders or in 1-3% hydrochloric acid solution (10-15 drops in half a glass of water); children 0.05-0.3 G in 0.5-1% hydrochloric acid solution.

Contraindications to taking pepsin are hyperacid gastritis, exacerbation of stomach ulcers. The drug used in therapeutic doses does not have side effects.

Release form: powder. Storage: in well-closed jars in a cool (from 2 to 15 °), protected from light place.

The drug acidine pepsin(Acidin-pepsinum) contains 1 part of pepsin and 4 parts of betaine hydrochloride, which is hydrolyzed in the stomach to form free hydrochloric acid (0.4 G betaine corresponds to about 16 drops of dilute hydrochloric acid). Tablets of acidin-pepsin (0.5 and 0.25 G) is dissolved in half a glass of water and taken 3-4 times a day with meals. Similar tablets produced abroad - "Acidol- pepsin”, “Betacid”, “Acipepsol”, “Pepsamine”.

Bibliographer.: Antonov V.K. Chemistry of proteolysis, p. 31, M., 1983; Mosolov V.V. proteolytic enzymes, p. 101, M., 1971, Radbil O.S. Pharmacological bases for the treatment of diseases of the digestive system, p. 78, M., 1976.

Good afternoon, dear readers! Probably, you had to meet with the concept of "pepsin". And for some reason it is constantly used in conjunction with the definition of "beef". Although it is known that this enzyme is used to make cheeses, including homemade ones.

How to unravel these biological-linguistic labyrinths, now I will try to tell you.

First, let's understand the basic terms.

The main "character" of this story is rennet and its components. This substance is produced in the stomachs of ruminants, and more specifically, by the glands of the fourth section of the stomach, which bears the strange name "abomasum".

This is a natural compound and is used as a catalyst in the production of cheese. The two main constituents of rennet are pepsin and chymosin. The purpose of chymosin is the primary breakdown of milk components, as a result of which the insoluble protein casein is formed. The latter, in turn, undergoes "factorization" already with the help of pepsin.

As a result, milk is divided into two fractions - curd-like protein mass and milk whey. Moreover, the protein component after contact with two elements of rennet is already broken down into amino acids, which are easily processed by the body.

The main thing to know about the functions of pepsin is its ability to help digest protein. Without it, we could drink milk in buckets, and not get the right portion of the “building” component so important for tissues.

That's the story!

Historians assure us that we owe the discovery of what pepsin is in cottage cheese to the Arab nomads. It is clear that they did not know such a word, and they simply had no time to engage in subject cheese making. As is often the case in the long and fascinating biography of the development of human society, everything happened by chance.

Traveling through the hot desert, the wanderers carried milk with them. The containers were bags made from the stomachs of livestock. After some time of travel, the nomads found that the milk had curdled, turned into a clot floating in a translucent whey.

These components and the mechanism of milk curdling were subjected to close analysis only in the forties of the last century, at the same time the concept of “beef pepsin” appeared. And to this day, pepsin is a natural substance, it is not produced artificially.

You can buy rennet in pharmacies and specialized stores, it is available in the form of a liquid or powder. It is used in cooking to make meat dishes more soft, as well as to make cottage cheese and cheese of various varieties.

Cheese-boron in detail

Why is pepsin synthesized in the stomachs of livestock and a number of other artiodactyls?

Initially, rennet was programmed by nature as an aid in the breakdown, assimilation of milk protein by newborn calves, lambs, goats and other young ruminants. In addition, it is also present in the gastric juice of birds.

As for the other component of rennet, that is, chymosin, we will not go into the details of chemical analysis, but we will dwell on a very important point.

To start the mechanism of its functioning, a certain environment is required: the presence of hydrochloric acid, calcium ions and pH (hydrogen index) in the gastric juice is less than 5 units. This must be taken into account when planning both the manufacture of cheese at home, and its use, competent mixing with other food products.

Remember that if the acidity of the stomach is low, an alkaline environment prevails, then chymosin in it loses activity, milk and other protein products will be poorly absorbed. Accordingly, you should not eat homemade and industrially produced cheese, say, along with lemons or apples, berries, apricots and bananas, and other "alkaline" delicacies.

Another tip: don't make your own sourdough starter. It is difficult to calculate the desired proportions of acidity, and the process can take from 12 hours to a day. If we do not guess with the optimal level of acid formation, the cheese will lose its delicate taste. If the acidity of the fermenting composition is excessively high, the product will acquire a bitterness that is not always pleasant to the taste.

Otherwise, our cheese can quickly deteriorate, as pathogenic bacteria can develop in it.

When thinking about how to make tender homemade cheese, and not too expensive in terms of finances, it is better to choose the option using ready-made beef pepsin.

Beef pepsin at the preparation stage is thoroughly cleaned of fat and other insoluble impurities. At the output in the finished product, such impurities should not be more than 3% by weight. The preparation is made by the extraction method, then comes the salting out stage, the final moment is freeze-drying. Chymosin in the composition on average about 10%.

The production process resembles the technology for the production of medicines and ideally should have the same careful control at different stages and at the final stage of testing the finished product.

Themselves cheese makers

So, we decided that we would prefer industrial pepsin in our culinary research. It will cause milk coagulation in an hour or even a slightly shorter period of time, depending on the variety and other parameters of the feedstock.

By the way, about the cost-effectiveness of home cheese making. Just one bag of "store" pepsin is enough to ferment 100 liters of milk, and at the output we get about 12 kilograms of finished products, delicious and healthy cheese.

When choosing a recipe for homemade cheese, please note that if you choose the option of cheese making without the use of pepsin, then milk with a low percentage of fat content, as well as ultra-pasteurized milk, is not suitable for it. The use of pepsin expands the range of possible feedstock. Varieties with varying degrees of fat content are already suitable here, even powdered, with some skill, can be “tame” and turned into the desired cheese. Only milk with an excess of preservatives will not work.

The practice of both industrial cheesemaking and amateur culinary experiments proves this with success. With purchased rennet, you can create masterpieces: various soft cheeses, as well as brine varieties, feta cheese, cottage cheese in endless variations of additional components, shades, “raisins”.

With beef pepsin, any of these components of a true gourmet menu acquires a delicate softness, even texture without annoying lumps, hard grains. Yes, and the piquancy of taste sensations is added.

One of the options for making rennet cheese.

We dissolve pepsin in water at room temperature, pour it into milk heated to 35 degrees. After half an hour or 40 minutes, we will see that a cheese clot has formed. Bring to readiness in a water bath at a temperature of about 40 degrees. When we get the cottage cheese of the desired consistency, we filter the mass, wrap it in a cloth, squeeze it under pressure. Optionally, additional ingredients can be added to the still soft mass.

Surely, after reading this article, I interested you and one recipe for making cheese at home will not be enough for you. It is so?

What will you find in this book?

• recipes for dishes from homemade dairy products. Dishes such as sour cream, butter, cottage cheese, cheese, kefir, yogurt, cream, whey.
• many color photographs;
• simple cooking tools;
• affordable theory for cooking at home.

By studying this book and implementing its recipes in your kitchen, you and your family will truly appreciate the taste of the prepared dishes. After all, they will be not only tasty, but also useful.

You can order this miracle helper here.

Related articles:

Dear friends, here we are "made" homemade cheese with the help of this special ingredient: beef pepsin.

And if you know or tried to cook homemade cheese according to a different recipe, share it in the comments. It will be interesting for me to read, and then try it in practice.

That's all for me, see you soon!

In the digestive tract, the enzyme pepsin is responsible for the digestion of animal proteins, as well as cereals, legumes, dairy products, and helps the body to better absorb vitamin B9 or iron. When working properly, it is produced in the cells of the gastric mucosa, and in case of deficiency, drugs are prescribed that contain pepsin.

What is this substance?

Pepsin is the main enzyme of the digestive systems of the endopeptidase class. The enzyme is initially produced as pepsinogen, but is converted to pepsin by the action of gastric juice. The protein-splitting enzyme supplies amino acids to the entire body, which are used as a source of energy, and are broken down in the stomach only under the influence of enzymes. They also produce their own proteins, cell walls and other substances and structures.

Classification by type

Table of varieties of endopeptidases:

Group name	stomach enzymes	a brief description of	At what level of acidity are they active?
BUT	Uropepsin	Partially excreted through urine and used to analyze the proteolytic activity of gastric juice	Hydrolyzes at 1.5-2 pH
FROM	cathepsin or gastrixin	Located inside the cell and cuts peptide bonds	Pepsin and gastrixin are involved in hydrolysis at pH 3.2-3.5
IN	parapepsin or gelatinase	Divides gelatin and connective tissue proteins	pH for pepsin should not be higher than 5.6
D	Rennin or chymosis	An enzyme involved in the process of splitting milk with the help of calcium.	Operate in a neutral environment

Enzymes act on protein only in an acidic environment. Catalysts are produced by glands located near the walls of the fundic part of the stomach, the place with the lowest pH level. Gastrixin is found in all parts of the stomach. Enzymes complete the breakdown of proteins, and their breakdown product is soluble in water.

This is a very complex chemical process.

The catalyst is activated in the stomach in an acidic environment under the influence of hydrochloric acid. The cells of the mucous membranes of the organ produce a proenzyme. Pepsinogen is a functionally inactive form of the enzyme from which pepsin is derived. An inhibitor, pepstatin, is also released there, which is necessary so that the secretion of pepsin does not go beyond the normal range. As soon as pepsin enters the intestine, its function stops, but other enzymes enter the process of digestion.

In men, the release of proteases is 25% higher than in women.

Enzyme Functions

The main action of pepsin and other hydrolases is to cut large protein molecules into small pieces. The secreted enzymes are responsible for protein disaggregation, albumin breakdown, milk curdling, and gelatin dissolution. Proteolytic activity greatly simplifies the hydrolysis process. Catalysts are provided by:

• Protease action - splitting proteins into oligo- and polypeptides.
• Transpeptidase activity - oligopeptides are divided into amino acids and peptides, which provides cathepsin.
• Peptidase action - hydrolysis of polypeptides and amino acids.

What splits?

Biochemistry deals with the study of this issue. A protein molecule is a set of amino acids that are connected to each other. The cells of the body do not independently digest and assimilate such a volume of material, therefore, the splitting function is provided. In the process of protein digestion, pepsin performs the function of scissors - it cuts peptide bonds. The gradual destruction of the peptide molecule in half begins, then each part is further divided and more, until one amino acid is formed. They build their own muscle and internal proteins, as well as enzymes, hormones and other substances. In rare cases, the body releases energy from peptides for life.

Easily digestible and effective drugs.

When the body does not digest food well, it is recommended to use medicines based on pepsin and other enzymes. The fundic glands of the stomach of pigs produce enzymes that are used to make powder and tablets for medical purposes. , dyspepsia, achilia or other ailments with a deficiency of pepsin - an indication for the use of pepsin-containing drugs. One such remedy is Pepsinum. It is mixed with powdered sugar. It has a specific smell, creamy shade and pleasant taste. The required dose per day is up to half a gram of a single oral intake. Consume 2 to 3 times before meals or during. When the enzyme is active and working, it begins to break down proteins into polypeptides in the digestive tract.

"Acidin-Pepsin" is a medicine that consists of two enzymes in a ratio of 1: 4, which breaks down proteins and helps to separate free hydrochloric acid. The drug is used for dyspepsia, and anacid gastritis. The use depends on the age category and weight of the patient. Reception 3-4 times a day, during meals or after. It is recommended to dissolve in water. And also for better digestion of food, you can consume: "Akidolpepsin", "Akipepsol", "Betacid", "Pepsamine", "Pepsacid". And also enzymes help to cope with iron and other elements, if there is an excess of them.

Pepsin (Pepsinum) is an enzyme in the stomach. Molecular weight is 35,000. The pepsin molecule consists of 340 amino acid residues. Pepsin hydrolyzes proteins to . Optimum action at pH around 2.0. The precursor of pepsin, pepsinogen, produced by the cells of the gastric mucosa, is converted to pepsin in the presence of gastric juice. Pepsin - a preparation (Pepsinum siccum) - is obtained by extraction from the mucous membrane of the stomachs of pigs, sheep and calves. It is used for hypo- and anacid gastritis, dyspepsia. Pepsin is administered orally at 0.2-0.5 g per dose 2-3 times a day before meals or during meals in the form of a powder or in a 1-3% solution of diluted hydrochloric acid. Release form: powder.

In the fundic glands of the stomach, 1 g of pepsinogen is produced daily, which is activated in the stomach cavity under the action of hydrochloric acid, turning into pepsin. The molecular weight of pepsinogen is 42,000, pepsin is 35,000. The optimum pH for pepsin is 1.5-2. Most of the enzyme enters the stomach and plays an active role in the process of digestion, but a certain amount of pepsinogen passes into the bloodstream and is excreted by the kidneys.

Pepsin breaks down almost all proteins, with the exception of some protamines. Synthetic peptides are also hydrolyzed if there are L-amino acids on both sides of the broken bond. Otherwise, there is little specificity for amino acids, although there is a preference for aromatic amino acids.

Pepsin is an enzyme in the stomach. Refers to the group of proteinases (see Proteases); obtained in crystalline form. Mol. in. 35,000, isoelectric point approx. pH = 1. In addition to pepsin, in gastric juice (see) there are several concomitant proteolytic enzymes (for example, gastrixin).

The purest preparations of pepsin are obtained by chromatography on columns with diethylaminoethylcellulose. The pepsin molecule is a single polypeptide chain of approximately 340 amino acid residues. Dephosphorylation of pepsin does not destroy its enzymatic activity. Pepsin is most stable at pH=5-5.5; self-digestion occurs in a more acidic environment. Pepsin hydrolyzes proteins to peptides; amino acids are also found among the products of hydrolysis. Peptide bonds formed by various amino acid residues undergo hydrolysis. Pepsin is able to catalyze the transpeptidation reaction (transfer of amino acid residues from one peptide to another). The optimum action of pepsin is around pH=2; at pH=5 pepsin causes curdling of milk, at pH above 6 it is rapidly inactivated.

An inactive precursor of pepsin, pepsinogen, produced by the cells of the mucous membrane of the fundus of the stomach, is converted to pepsin in the presence of hydrochloric acid contained in gastric juice. The activation process proceeds autocatalytically at maximum speed at pH=2. From the N-terminal section of the pepsinogen molecule, several peptides are cleaved off with a total mol. in. OK. 8000. A pepsin inhibitor has been isolated - a peptide with a mol. in. OK. 3000, which is formed from pepsinogen when it is converted to pepsin. During activation, an intermediate compound of pepsin with a polypeptide inhibitor is formed, which easily dissociates at low pH values, and the inhibitor is digested by pepsin. At pH>5, dissociation is insignificant and pepsin inhibition occurs in almost stoichiometric ratios.

Pepsin(a drug). Pepsin (Pepsinum siccum) is obtained by extraction from the mucous membranes of the stomachs of pigs, sheep or calves. Used as a means of replacement therapy for acute and chronic diseases of the digestive tract, accompanied by depletion of gastric juice endogenous pepsin. For therapeutic use, pepsin is diluted to the official standard (1:100) with milk sugar. Assign inside adults 0.2-0.5 g per reception 2-3 times a day before meals or during meals in the form of a powder or 1-3% solution of diluted hydrochloric acid; children - from 0.05 to 0.5 g in a 0.5-1% solution of diluted hydrochloric acid. Release form: powder.