Pepsin

“ In general properties and reactions, pepsin and trypsin may be closely related; both are products of the katabolic action of specific protoplasmic cells, but the inner nature or structure of the two must be quite different. Pepsin, as we have seen, is powerless to produce any change in proteid bodies unless acids are present to lend their aid. Furthermore, pepsin is limited in its action to the production of proteoses and peptones, while trypsin gives rise to a series of hydrolytic cleavages which result in the ultimate formation of comparatively simple bodies. ”

“ Dosage: 30 Gm. or 1 ounce (U.S.P.) .
*Pepsinum (Pepsin.) , Pepsin, U.S.P.—Contains a proteolytic ferment or enzyme from the stomach of the hog.
White or yellowish scales, grains, or powder, having a slightly acid or saline taste and no offensive odor. Soluble in water (1:50) ; [Pg 156] nearly insoluble in alcohol. Digests 3000 times its own weight of coagulated egg albumen.
Action and Uses: Used to assist in the gastric digestion of proteins. Usually superfluous, since gastric juice generally contains sufficient pepsin to perform gastric digestion. ”

“ I began taking syrup of pepsin to artificially digest my food and thus take some of the burden off my stomach. A friendly druggist took sufficient interest in me to inform me that there was not enough pepsin in the ordinary digestive syrups and elixirs to digest a mosquito’s dinner. When asked why this ferment was omitted from such preparations, the druggist confided to me in a whisper: “Pepsin is a drug that costs money, while diluted molasses is cheap.” ”

“ Pepsin, in the presence of hydrochloric acid, acts on proteids, and changes them into proteoses Peptone and proteoses and peptone. Comparatively little food is completely peptonized in gastric digestion. Proteoses are intermediate products between food proteids and peptone, being the principal product of the action of the gastric juice. Thus it is seen that this stomach-action is only preparatory for the digestive processes of the intestines. ”

“ The results certainly favor the view that the conversion of the primary products of gastric digestion into true peptone is a slow and gradual process, even under the most favorable circumstances, and that this lack of complete peptonization is not due to accumulation of the products of digestion, but is rather an inherent quality of pepsin-proteolysis under all circumstances. ”

“ If no ice is convenient bring the milk to a boil for the same purpose. If the action of the pepsin be continued for a much longer period the milk becomes bitter to the taste from the development of excess of peptones. Predigested foods should not be used over a long period or the digestive functions of the stomach may atrophy from disuse. ”

“ One cannot fail to be impressed with the resemblance in functional power between the unformed ferments as a class and cell-protoplasm. To what can we ascribe the particular functional power of each individual ferment? Why, for example, does pepsin act on proteid matter only in the presence of acid, and trypsin to advantage only in the presence of alkalies? Why does pepsin act only on proteid matter, and ptyalin only on starch and dextrins? Why does trypsin produce a different set of soluble products in the digestion of albumin than pepsin does? ”

“ Probably you know how pepsin is got for the market—how they pen pigs so that their snouts almost touch food which they can by no straining and struggling reach; how the unhappy creatures soon begin to drip, then to slobber, then to stream into the receiving trough under their jaws the pepsin which the sight of the food starts their stomachs to secreting. ”

“ It is probably richer in vegetable pepsin than any other plant in existence—a pepsin which neutralizes either alkaline or acid conditions in the stomach. It is said that a tough steak, wrapped in the leaf of the papaya tree overnight, becomes tender as the result of the digestive action of the pepsin in it. ”

“ Thus, very recently, Bertels40 and Dubs41, working under Salkowski’s direction, have called attention to the peculiar behavior of pepsin to chloroform; their results showing, first, that small amounts of this agent tend to increase the proteolytic power of the enzyme, while larger amounts decrease its digestive power. ”

“ So far as is at present known the unorganised ferments in the dung, besides those which are secreted by the bacteria, are mostly digestive ferments114 —pepsin, pancreatin, and trypsin—certain quantities of which pass out of the animal’s body in an unchanged condition. Of these, pepsin only acts in an acid solution, and, although fresh bate liquor is faintly acid to litmus, it quickly becomes neutralised by the lime in the skins, so that the action of this ferment can only be limited in extent. ”

“ The gastric juice, of which about seventy ounces is formed by the stomach daily, con [Pg 100] tains in addition to hydrochloric acid, a quantity of pepsin, which with the acid dissolves all sorts of proteids or albuminous substances, like meat and eggs; and it also contains rennet, which coagulates milk. The gastric juice digests proteids by converting them into pepsin, an exceedingly soluble substance which passes readily into the blood.
The bile manufactured by the liver has the function of digesting fats. Fats are not changed chemically, as are starches and proteids. ”

“ In pepsin-proteolysis we have to deal, in my opinion, with a series of progressive hydrolytic changes in which peptones are the final products of the transformation. Commencing with the formation of acid-albumin or syntonin, hydrolysis and cleavage proceed hand in hand, under the guiding influence of the proteolytic enzyme, and each onward step in the process is marked by the appearance of a new body corresponding to the extent of the hydrolysis ”

“ Pep′tics, digestion considered as a science: the digestive organs; Pep′togen, a substance producing peptone, any preparation that facilitates digestion.—adjs. Peptogen′ic, Peptog′enous, Pepton′ic.—ns. Pep′tōne, one of a class of albumenoids formed by the action of the chemical ferment pepsin and hydrochloric acid, the latter first converting into a syntonin or acid protein, the former converting this syntonin into peptone—they are soluble in water, are not coagulated by boiling, and pass readily through an animal membrane, being therefore easily absorbed ”

“ Peptones are truly formed, and many times in large amount, but never under any circumstances have I been able to effect a complete transformation of any proteid into true peptone by pepsin-proteolysis; there is always found a certain amount of proteoses more or less resistant to the further action of the ferment. Obviously, the nature and proportion of the individual products formed in any digestive experiment are dependent greatly upon the attendant conditions ”

“ In fact, there seems to be a tendency on the part of some who are more or less familiar with the advances made in our knowledge of the products of pepsin-proteolysis to question the existence of these different bodies, or to show at least a spirit of indifference toward these recent facts which have been gradually accumulated, and I may say accumulated at the expense of considerable labor. ”

“ In the stomach, the hydrochloric acid helps to make it soften and swell, and then pepsin begins its digestion. Protein, like fat and carbohydrate, can be subdivided into smaller and smaller portions, finally being reduced to a form which the body can absorb, namely, amino acids, of which there may be 17 or 18 kinds from a single protein. ”

“ When the food reaches the stomach, gastric juice is secreted. This juice contains a ferment called pepsin and hydrochloric acid. Pepsin is only active in an acid media. Starch digestion proceeds in the stomach to such a time—stated as from 15 to 30 minutes—when the acid gastric juice has been poured out in sufficient quantity to neutralise the alkalinity of the saliva. The gastric juice acts upon the proteids only. After a time the liquefied contents of the stomach are passed into the first portion of the small intestine, called the duodenum. ”

“ The deutero-body, on the other hand, once formed is more rapidly converted into peptone, but even this is in no sense a rapid process. Hence, in the artificial digestion of proteids with pepsin-hydrochloric acid, solubility of the proteids may be quite rapid, and even complete in a very short time, but the resultant products will be mainly proteoses and not peptones. ”

“ The resulting extract represents, in all its constituents, the lean meat employed, but with the fibrine, albumen, and gelatine, changed into their respective peptones, or soluble forms. This change is effected solely by the pepsin and hydrochloric acid, or artificial gastric juice, without the evolution or absorption of any secondary products. ”

“ In any active pancreatic digestion of either a native proteid, or of the products of pepsin-proteolysis, the anti-group is represented mainly by antipeptone, although there is often found a small amount of a peculiar antialbumid-like body, insoluble in the weak alkaline fluid. ”

“ Again, trypsin exhibits its peculiar proteolytic power in the presence of sodium carbonate, a salt which has an immediate destructive action upon pepsin. Hence, a medium which is favorable for the action of the one ferment may be directly antagonistic to the action of the other. ”

“ In pancreatic digestion, proteids are exposed to the action of an enzyme of much greater power than pepsin, one endowed with a far greater range of activity, and consequently proteolysis as it occurs in the small intestine becomes a broader and more complicated process. As you well know, the ferment trypsin manifests its power not only in a more rapid transformation of insoluble proteids into soluble and diffusible products, but there is a diversity in the character of the many products formed which testifies to the profound alterations this ferment is capable of producing. ”

“ Absorption of the products of digestion tends to increase the activity of the secreting cells, but we have no tangible proof that any particular kinds of food are directly peptogenous, i.e., that they lead to a storing up in the gastric cells, for example, of pepsinogen, although it may be that the so-called peptogenous foods give rise to a more active conversion of pepsinogen into pepsin.23 As already stated, the zymogen is manufactured directly from the cell-protoplasm, and the constructive power is certainly not directly controlled by the character of the food ingested. ”

“ Owing to the prominent rôle they play in the human body in connection with digestive processes they have been subjected to exhaustive study. Two chief groups are recognized, the peptic enzymes, of which pepsin, the enzyme of the gastric juice, is the type, and the tryptic enzymes, the best known of which is the trypsin secreted by the mammalian pancreas. ”

“ Stated in different language, it is apparently the purpose of digestion, through the enzymes, pepsin, trypsin and erepsin, to thoroughly dismember the protein molecule so that no vestige of its original structure remains; while out of the many fragments or chemical groups so split apart the body can reconstruct proteins adapted to its own particular needs. This means synthesis of a most marked kind, quite different in character from that implied by the hypothetical transformation of absorbed proteoses and peptone in the mucous membrane of the intestine. ”

“ The gastric juice does not act on carbo-hydrates or hydrocarbons to any very noticeable degree. Its essential property is the conversion of proteids into peptones, and the ferment by which this is effected is called pepsin. ”

“ What was needed, and for which many of the most patient investigators were searching, was a diastase which would do for the starchy elements of the food what pepsin does for the proteids. The digestion of food in man has been the subject of much patient and methodical study and investigation during the last two decades, notably by Ewald, Kellogg, Hayem, and Winter, and others, resulting in the placing of the therapeutics of disordered digestion upon an exact scientific basis. ”

“ Both the seeds and the fruit contain an active principle called papain, which is really a vegetable pepsin, that has the effect of greatly assisting in the assimilation of all food with which it is eaten, hence it is a valuable remedy in the case of dyspepsia, and persons who take the fruit regularly are never subject to this exceedingly troublesome disease. ”

“ Nor do we at present know what effects are produced by the absorption of the various digestive juices themselves. That such absorption takes place there can be little doubt. It has been demonstrated in the case of the bile, which is absorbed with great rapidity from the intestine and reëxcreted by the liver, so that it does not pass into the general circulation at all. But what becomes of the other digestive fluids, and the ferments they contain? The pepsin finds it way in minute quantities through the liver, and has been discovered in various tissues of the body and in the urine. ”

“ Cultivated fruits such as apples, pears, cherries, strawberries, grapes, etc., contain on analysis very similar proportions of the same ingredients, which are about eight per cent of grape sugar, three per cent of pectones, one per cent of malic and other acids, and one per cent of flesh-forming albuminoids, with over eighty per cent of water. Digestion depends upon the action of pepsin in the stomach upon the food, which is greatly aided by the acids of the stomach. ”

“ Dosage: 8 Cc. or 2 fluidrachms (N.F.) .
Pepsinum Saccharatum (Pepsin. Sacchar.) , Saccharated Pepsin, N.F.—Pepsin (10%) with sugar of milk.
Dosage: 1 Gm. or 15 grains (N.F.) .
Succus Citri et Pepsinum (Suc. Cit. et Pepsin.) , Lime Juice and Pepsin, N.F. (Succus Limettae cum Pepsino, N.F. III) .—Glycerite of pepsin (40%) and lime juice.
Dosage: 8 Cc. or 2 fluidrachms (N.F.) . ”