It is one of three principal endopeptidases (enzymes cutting proteins in the middle) in the human digestive system, the other two being chymotrypsin and trypsin. There are also exopeptidases which remove individual amino acids at both ends of proteins (carboxypeptidases produced by the pancreas and aminopeptidases secreted by the small intestine). During the process of digestion, these enzymes, each of which is specialized in severing links between particular types of amino acids, collaborate to break down dietary proteins into their components, i.e., peptides and amino acids, which can be readily absorbed by the small intestine. The cleavage specificity of pepsin is broad, but some amino acids like tyrosine, phenylalanine and tryptophan increase the probability of cleavage.
Digestion is the breakdown of large insoluble food compounds into small water-soluble components so that they can be absorbed into the blood plasma. In certain organisms, these smaller substances are absorbed through the small intestine into the blood stream. Digestion is a form of catabolism that is often divided into two processes based on how food is broken down: mechanical and chemical digestion. The term mechanical digestion refers to the physical breakdown of large pieces of food into smaller pieces which can subsequently be accessed by digestive enzymes. Mechanical digestion takes place in the mouth through mastication and in the small intestine through segmentation contractions. In chemical digestion, enzymes break down food into the small compounds that the body can use.
In the human digestive system, food enters the mouth and mechanical digestion of the food starts by the action of mastication (chewing), a form of mechanical digestion, and the wetting contact of saliva. Saliva, a liquid secreted by the salivary glands, contains salivary amylase, an enzyme which starts the digestion of starch in the food. The saliva also contains mucus, which lubricates the food; the electrolyte hydrogencarbonate (HCO3), which provides the ideal conditions of pH for amylase to work; and other electrolytes (Na, K, Cl). About 30% of starch is hydrolyzed into disaccharide in the oral cavity (mouth). After undergoing mastication and starch digestion, the food will be in the form of a small, round slurry mass called a bolus. It will then travel down the esophagus and into the stomach by the action of peristalsis. Gastric juice in the stomach starts protein digestion. Gastric juice mainly contains hydrochloric acid and pepsin. In infants and toddlers, gastric juice also contains rennin to digest milk proteins. As the first two chemicals may damage the stomach wall, mucus and bicarbonates are secreted by the stomach. They provide a slimy layer that acts as a shield against the damaging effects of chemicals like concentrated hydrochloric acid while also aiding lubrication. Hydrochloric acid provides acidic pH for pepsin. At the same time protein digestion is occurring, mechanical mixing occurs by peristalsis, which is waves of muscular contractions that move along the stomach wall. This allows the mass of food to further mix with the digestive enzymes. Pepsin breaks down proteins into peptides or proteoses, which are further broken down into dipeptides and amino acids by enzymes in the small intestine. Studies suggest that increasing the number of chews per bite increases relevant gut hormones and may decrease self-reported hunger and food intake.
Rennet (/ˈrɛnɪt/) is a complex set of enzymes produced in the stomachs of ruminant mammals. Chymosin, its key component, is a protease enzyme that curdles the casein in milk. In addition to chymosin, rennet contains other enzymes, such as pepsin and a lipase.
Rennet has traditionally been used to separate milk into solid curds and liquid whey, used in the production of cheeses. Rennet from calves has become less common for this use, to the point that less than 5% of cheese in the United States is made using animal rennet today. Most cheese is now made using chymosin derived from bacterial sources.
There are two types of gastric gland, the exocrine fundic or oxyntic gland, and the endocrine pyloric gland. The major type of gastric gland is the fundic gland that is present in the fundus and the body of the stomach making up about 80 per cent of the stomach area. These glands are often referred to simply as the gastric glands. The fundic gland contains the parietal cells that produce hydrochloric acid and intrinsic factor, and chief cells that produce pepsinogen and gastric lipase.
Pepsi is a carbonatedsoft drink with a cola flavor, manufactured by PepsiCo which serves as its flagship product. In 2023, Pepsi was the second most valuable soft drink brand worldwide behind Coca-Cola; the two share a long-standing rivalry in what has been called the "cola wars".
Pepsi, originally created in 1893 by Caleb Bradham and named "Brad's Drink," was first sold in his drugstore in New Bern, North Carolina. Renamed Pepsi-Cola in 1898 due to its supposed digestive benefits, its name was shortened to Pepsi in 1961. The beverage's formula initially included sugar and vanilla but not pepsin, despite speculation on the origin of its name. Early on, Pepsi struggled with financial stability, going bankrupt in 1923 but was subsequently purchased and revived by Charles Guth, who reformulated the syrup. Pepsi gained popularity with the introduction of a 12-ounce bottle during the Great Depression and clever marketing strategies like the "Nickel, Nickel" jingle, doubling sales by emphasizing its value.
A proteose is any of various water-solublecompounds that are produced during in-vitro or in-vivo hydrolytic breakdown of proteins a little before producing amino acids. It forms after breaking down of polypeptides by proteases such as gastric pepsin. In addition to proteoses, peptones are also formed at this stage. The difference between peptones and proteoses is that proteoses are precipitated from solution by half saturation with ammonium sulfate, while peptones don't react even with fully saturated ammonium sulfate.
