============================================================_On Digestive Proteolysis Being the Cartwright Lectures for 1894

Substance. | C | H | N | S | O | P | Ash.| Origin. | Author.

------------+-----+----+-----+----+-----+----+-----+-----------+---------------

Serum- |53.05|6.85|16.04|1.77|22.29| |{0.57|Serum from |Hammarsten.[54]

albumin | | | | | | |{-- |horse blood|

Serum- |52.25|6.65|15.88|2.27|22.95| |{1.84|Pleural |Hammarsten.[54]

Egg-albumin |52.25|6.90|15.25|1.93|23.67| | |Non- |Hammarsten.[54]

Egg-albumin |52.33|6.98|15.89|1.83|22.97| | 1.11|Non- |Chittenden and

Lacto- |52.19|7.18|15.77|1.73|23.13| | |Cow’s milk |Sebelien.[56]

Vegetable- |52.25|6.76|16.07|1.48|23.44| | 0.70|Corn |Chittenden and

Vegetable- |53.02|6.84|16.80|1.28|22.06| | 0.82|Wheat |Osborne and

Proteose, |52.13|6.83|16.55|1.09|23.40| | 0.79|Hemialbu- |Kühne and

Proteose, |50.60|6.68|16.33|1.62|24.77| | 2.99|Corn |Chittenden and

Proteose, |51.86|6.82|17.32| | | | 0.25|Wheat |Osborne and

Proteose, |49.98|6.95|18.78| | | | 1.80|Flax-seed |Osborne.[60]

Proteose, |46.52|6.40|18.25| | | | 2.20|Cocoanut |Chittenden and

Vitellin, |51.71|6.84|18.12|0.85|22.48| | 1.20|Corn |Chittenden and

Vitellin, |51.60|6.97|18.80|1.01|21.62| | 0.30|Squash-seed|Chittenden and

Vitellin, |51.81|6.94|18.71|1.01|21.53| | 0 |Squash-seed|Chittenden and

Vitellin, |51.48|6.94|18.60|0.81|22.17| | 0.54|Flax-seed |Osborne.[60]

Vitellin, |51.03|6.85|18.39|0.69|23.04| | 0.49|Wheat |Osborne and

Vitellin, |51.63|6.90|18.78|0.90|21.79| | 0.56|Hemp-seed |Chittenden and

Vitellin, |51.31|6.97|18.75|0.76|22.21| | 0.03|Castor bean|Osborne.[63]

Vitellin, |52.18|6.92|18.30|1.06|21.54| | 0.20|Brazil nut |Osborne.[63]

Vitellin, |51.23|6.90|18.40|1.06|22.41| | 0.25|Cocoanut |Chittenden and

Myosin, 13 |52.82|7.11|16.77|1.27|21.90| | 1.45|Muscle- |Chittenden and

Myosin, |52.68|7.02|16.78|1.30|22.22| | 0.63|Corn or |Chittenden and

Myosin, |52.18|7.05|17.90|0.53|22.34| | 0.10|Oats |Osborne.[65]

Paraglobulin|52.71|7.01|15.85|1.11|23.24| | 0.30|Blood |Hammarsten.[66]

Fibrinogen |52.93|6.90|16.66|1.25|22.26| | 1.75|Blood |Hammarsten.[67]

Zein |55.23|7.26|16.13|0.60|20.78| | 0.43|Corn or |Chittenden and

Gliadin |52.72|6.86|17.66|1.14|21.62| | 0.51|Wheat |Osborne and

Gliadin |53.01|6.91|16.43|2.26|21.39| | |Oats |Osborne.[63]

| | | | | | | | |

Glutenin |52.34|6.83|17.49|1.08|22.25| | |Wheat |Osborne and

Coagulated |52.33|6.98|15.84|1.81|23.04| | 0.27|Egg-albumin|Chittenden

Coagulated |51.58|6.88|18.80|1.09|21.65| | 0.25|Vitellin, |Chittenden

Fibrin |52.68|6.83|16.91|1.10|22.48| | 0.56|Blood |Hammarsten.[67]

Oxyhæmo- |53.85|7.32|16.17|0.39|21.84| | 0.43|Blood of |Hoppe-

globin | | | | | | | Fe.|dog | Seyler.[68]

Oxyhæmo- |54.71|7.38|17.43|0.48|19.60| | 0.39|Blood of |Hütner.[69]

globin | | | | | | | Fe.|pig |

Mucin |50.30|6.84|13.62|1.71|27.53| | 0.33|From snail |Hammarsten.[70]

| | | | | | | | |

Mucin |48.84|6.80|12.32|0.84|31.20| | 0.35|Submaxil- |Hammarsten.[71]

Chondro- |47.30|6.42|12.58|2.42|31.28| | |Cartilage |Mörner.[72]

Nuclein |50.60|7.60|13.18| | |1.89| |Human brain|V. Jaksch.[73]

| | | | | | | | |

Nuclein |49.58|7.10|15.02| | |2.28| |Pus |Hoppe-

Casein |52.96|7.05|15.65|0.71|22.78|0.84| |Cow’s milk |Hammarsten.[75]

| | | | | | | | |

Casein |53.30|7.07|15.91|0.82|22.03|0.87| 0.98|Cow’s milk |Chittenden and

Nucleo- |48.41|7.21|16.85|0.70|24.41|2.42| |Leucocytes |Lilienfeld.[77]

Gelatin |49.38|6.81|17.97|0.71|25.13| | 1.26|Connective |Chittenden and

Elastin |54.24|7.27|16.70|0.30|21.79| | 0.90|Neck-band |Chittenden

Elastin |53.95|7.03|16.67|0.38|21.97| | 0.72|Aorta |Schwarz.[80]

| | | | | | | | |

Keratin |49.45|6.52|16.81|4.02|23.20| | 1.01|White |Kühne and

Neurokeratin|56.99|7.53|13.15|1.87|20.46| | 1.35|Human brain|Kühne and

Reticulin |52.88|6.97|15.63|1.88|22.30|0.34| 2.27|Reticular |Siegfried.[83]

------------+-----+----+-----+----+-----+----+-----+-----------+---------------

[A] Many of these results represent the average of a large number of

individual analyses.

[54] Jahresbericht f. Thierchemie, Band 11, p. 19.

[55] Studies in Physiol. Chemistry, Yale Univer., vol. 2, p. 126.

[56] Zeitschr. physiol. Chem., Band 9, p. 463.

[57] Amer. Chemical Journal, vols. 13 and 14.

[58] Ibid., vol. 15, p. 379.

[59] Zeitschr. f. Biol., Band 19, p. 198.

[60] Amer. Chemical Journal, vol. 14, p. 629.

[61] Not hitherto published.

[62] Journal of Physiology, vol. 11, p. 435.

[63] Amer. Chemical Journal, vol. 14, p. 662.

[64] Studies in Physiol. Chemistry, Yale University, vol. 3, p. 115.

[65] Fourteenth Annual Report Conn. Ag. Exp. Sta., 1890; 2d paper,

Amer. Chemical Journal, vol. 14, p. 212.

[66] Pflüger’s Archiv f. Physiol., Band 22, p. 489.

[67] Ibid., Band 22, p. 479.

[68] Hoppe-Seyler’s Med. Chem. Untersuch, p. 189.

[69] Hoppe-Seyler’s Chem. Analyse, 6th auflage, p. 275.

[70] Pflüger’s Archiv f. Physiol., Band 36. p. 392.

[71] Zeitschr. f. physiol. Chem., Band 12. p. 185.

[72] Jahresbericht f. Thierchemie, Band 18, p. 219.

[73] Pflüger’s Archiv f. Physiol., Band 13, p. 469.

[74] Hoppe-Seyler’s Med. Chem. Untersuch, p. 489.

[75] Zeitschr. f. physiol. Chem., Band 7, p. 269.

[76] Studies in Physiol. Chemistry, Yale University, vol. 2, p. 172.

[77] Du Bois Reymond’s Archiv f. Physiol., 1892, p. 170.

[78] Journal of Physiology, vol. 12. p. 23.

[79] Studies in Physiol. Chemistry, Yale University, vol. 3, p. 19;

also Zeitschr. f. Biol., Band 25, p. 368.

[80] Zeitschr. f. physiol. Chem., Band 18, p. 491.

[81] Zeitschr. f. Biol., Band 26, p. 304.

[82] Ibid., p. 301.

[83] Jahresbericht f. Thierchemie, Band 22, p. 15.

In considering the results tabulated above, it is to be remembered

that all of these bodies, with the exception of keratin, neurokeratin,

and reticulin, are more or less digestible in either gastric or

pancreatic juice, or indeed in both fluids. I will not take time here

to point out the obvious genetic relationships and differences in

composition shown by the above data, but will immediately call your

attention to the fact that there are other and more important points

of difference between many of these proteids which are hidden beneath

the surface, and which a simple determination of composition will not

bring to light. I refer to the chemical constitution of the bodies, to

the way in which the individual atoms are arranged in the molecule,

on which hinges more or less the general properties of the bodies and

which in part determines their behavior toward the digestive enzymes,

as well as toward other hydrolytic agents. These differences in inner

structure can only be ascertained by a study of the decomposition

products of the proteids, and of the way in which the complex molecules

break down into simpler. The nature of the fragments resulting from the

decomposition of a complex proteid molecule, gives at once something

of an insight into the character of the molecule. Thus, egg-albumin

exposed to the action of boiling dilute sulphuric acid yields, among

other fragments, large quantities of leucin and tyrosin, the latter

belonging to the aromatic group and containing the phenyl radical.

Collagen, or gelatin, on the other hand, by similar treatment fails

to yield any tyrosin or related aromatic body, but gives instead

glycocoll or amido-acetic acid, in addition to leucin, lysin, and other

products common to albumin. Its constitution, therefore, is evidently

quite different from that of albumin, but the composition of the body

reveals no sign of it. Further, we have physiological evidence of this

difference in constitution in that gelatin, though containing even

more nitrogen than albumin, is not able to take the place of the latter

in supplying the physiological needs of the body; its food-value is of

quite a different order from that of albumin.

But while all of the individual proteids show many points of

difference, either in composition, constitution, reactions, or

otherwise, they are nearly all alike in their tendency to undergo

hydrolytic decomposition under proper conditions; the extent of the

hydrolysis and accompanying cleavage being dependent simply upon the

vigor or duration of the hydrolytic process.

Furthermore, all of the simple proteids, at least, give evidence of

the presence of two distinct groups or radicals, which give rise by

decomposition or cleavage to two distinct classes of products. These

two groups, which we may assume to be characteristic of every typical

proteid, Kühne has named the anti- and hemi-group respectively. This

conception of the proteid molecule is one of the foundation-stones

on which rest some of our present theories regarding the hydrolytic

decomposition of proteids, especially by the proteolytic enzymes.

Moreover, it is not a mere conception, for it has been tested so

many times by experiment that it has seemingly become a fact. The

two groups, or their representatives, can be separated, in part, at

least, by the action of dilute sulphuric acid (three per cent.) at

100° C. Thus, after a few hours’ treatment of coagulated egg-albumin,

about fifty per cent. of the proteid passes into solution, while there

remains a homogeneous mass, something like silica in appearance,

insoluble in dilute acid, but readily soluble in dilute solutions of

sodium carbonate. This latter is the representative of the anti-group,

originally named by Schützenberger[84] hemiprotein, but now called

antialbumid.[85] It is only slightly digestible in gastric juice, but

is readily attacked by alkaline solutions of trypsin, being converted

thereby into a soluble peptone known as antipeptone. In the sulphuric

acid solution, on the other hand, are found the representatives

of the hemi-group; viz., albumoses, originally known as one body,

hemialbumose,[86] together with more or less hemipeptone, leucin,

tyrosin, etc.

[84] Recherches sur l’albumine et les matières albuminoides. Bulletin

de la Société chimique de Paris, vols. 23 and 24.

[85] Kühne: Weitere Mittheilungen über Verdauungsenzyme und die

Verdauung der Albumine. Verhandl. d. Naturhist. Med. Ver. zu

Heidelberg, Band 1, p. 236.

[86] Kühne und Chittenden: Ueber die nächsten Spaltungsproducte der

Eiweisskörper. Zeitschr. f. Biol., Band 19, p. 159.

The fact that we have so many representatives of the hemi-group in

this decomposition is significant of the readiness with which the

so-called hemi-group undergoes change. All of its members are prone

to suffer hydration and cleavage, passing through successive stages

until leucin, tyrosin, and other simple bodies are reached. These,

and other similar crystalline bodies, are likewise the typical

end-products of proteolysis by trypsin, and presumably come directly

from the breaking-down of hemipeptone. Antipeptone, on the other

hand, is incapable of further change by the proteolytic ferment

trypsin. Hence, the hemi-group can be identified by the behavior of

the body containing it toward trypsin; _i.e._, it will ultimately

yield leucin, tyrosin, and other bodies of simple constitution to be

spoken of later on. The anti-group, however, will show its presence by

a certain degree of resistance to the action of trypsin, antipeptone

being the final product of its transformation by this agent; _i.e._,

leucin, tyrosin, etc., will not result. In this hydrolytic cleavage

of proteids the anti-group does not always appear as antialbumid. It

may make its appearance in the form of some related body, the exact

character of the product being dependent in great part upon the nature

of the hydrolytic agent, but in every case the characteristics of the

anti-group will come to the surface when the body is subjected to the

action of trypsin.

The above-described treatment of a coagulated proteid with water

containing sulphuric acid evidently induces profound changes in the

proteid molecule. The conditions are certainly such as favor hydration,

and in the case of complex molecules, like the proteids, cleavage might

naturally be expected to follow. Analysis of antialbumid from various

sources plainly shows that its formation is accompanied by marked

chemical changes. Thus, the following data, showing the composition of

antialbumid formed from egg-albumin and serum-albumin by the action

of dilute sulphuric acid at 100° C., gives tangible expression to the

extent of this change:

===========================================================

| |Antialbumid[87]| | Antialbumid[87]

| Egg- | from | Serum- | from

|albumin.| egg-albumin. |albumin.| serum-albumin.

--------+--------+---------------+--------+----------------

C.......| 52.33 | 53.79 | 53.05 | 54.51

H.......| 6.98 | 7.08 | 6.85 | 7.27

N.......| 15.84 | 14.55 | 16.04 | 14.31

--------+--------+---------------+--------+----------------

[87] Kühne und Chittenden: Zeitschr. f. Biol., Band 19, pp. 167 and 178.

In both cases there is a noticeable decrease in nitrogen, and a

corresponding increase in the content of carbon. Evidently, then,

this cleavage of the albumin-molecule into the anti-group on the one

hand, and into bodies of the hemi-group on the other, is accompanied

by chemical changes of such magnitude that their imprint is plainly

visible upon the resultant products; changes which certainly are far

removed from those common to polymerization.

This proneness of proteid matter to undergo hydration and subsequent

cleavage is further testified to by the readiness with which even such

a resistant body as coagulated egg-albumin breaks down under the simple

influence of superheated water at 130° to 150° C. Many observations are

recorded bearing on this tendency of proteid matter, but few observers

have carried their experiments to a satisfactory conclusion. A recent

study of this question in my own laboratory, has given some very

interesting results.[88] Thus, coagulated egg-albumin placed in sealed

tubes with a little distilled water and exposed to a temperature of

150° C. for three to four hours, rapidly dissolves, leaving, however,

an appreciable residue. The solution reacts alkaline, there is a

separation of sulphur, and in the fluid is to be found not albumin, but

two distinct albumose-like bodies, together with some true peptone, and

a small amount of leucin, tyrosin, and presumably other bodies.[89] The

albumose-like bodies are in many ways quite peculiar. In some respects

they resemble the albumoses formed in ordinary digestion; but in others

they show peculiarities which render them quite unique, so that they

merit the specific name of atmidalbumoses, as suggested by Neumeister.

What, however, I wish to call attention to here is the composition of

these albumoses. Prepared from coagulated egg-albumin by the simple

action of heat and water, they show a deviation from the composition of

the mother-proteid, which plainly implies changes of no slight degree.

This is clearly apparent from the following table:

==================================================================

--+----------+-------------+---------------+---------+------------

C | 52.33 | 55.13 | 55.04 | 51.99 | 53.79

H | 6.98 | 6.93 | 6.89 | 6.60 | 7.08

N | 15.84 | 14.28 | 14.17 | 13.25 | 14.55

S | 1.81 | 1.66 | --- | 0.98 | ---

O | 23.04 | 22.00 | --- | 27.18 | ---

--+----------+-------------+---------------+---------+------------

[88] Chittenden and Meara: A Study of the Primary Products Resulting

from the Action of Superheated Water on Coagulated Egg-albumin. Journal

of Physiology, vol. 15, p. 501.

[89] Compare Neumeister’s experiments on blood-fibrin. Ueber die

nächste Einwirkung gespannte Wasserdämpfe auf Proteine und über eine

Gruppe eigenthümlicher Eiweisskörper und Albumosen. Zeitschr. f. Biol.,

Band 26, p. 57.

Here we see that two of these primary albumoses formed by the action

of superheated water, like the previously described antialbumid, show

a loss of nitrogen with a marked increase in the content of carbon.

Evidently, they are related to the antialbumid formed by the action

of dilute acid. They are, however, soluble in water, and in many

ways differ from true antialbumid, but there is evidently an inner

relationship. The so-called deuteroatmidalbumose shows a still more

noticeable falling off in nitrogen and sulphur, while the content

of carbon is more closely allied to that of the mother-proteid. The

albumose precipitable by sodium chloride, although different from an

albumid, evidently comes from the anti-group and is a cleavage product

which in turn may undergo further hydration and splitting by continued

treatment. The so-called deutero-body, on the other hand, may well be a

representative of the hemi-group.[90]

[90] Compare Krukenberg, Sitzungsberichte der Jenaischen Gesellschaft

für Medicin, etc. 1886.

It is not my purpose here to enter into details connected with the

action of superheated water on proteids. Such a course would take

us too far from our present subject, but I do wish to emphasize the

fact that even the most resistant of proteids has an innate tendency

to undergo hydration and cleavage, and that even simple heating with

water alone, at a temperature slightly above 100° C., is sufficient to

induce at least partial solution of the proteid. Further, this solvent

action in the case of water and dilute acids, at least, is certainly

associated with marked chemical changes. It is not mere solution, it

is not simply the formation of one soluble body, but solution of the

proteid is accompanied by the appearance of a row of new products,

in which the terminal bodies are crystalline substances of simple

composition. Further, this conclusion does not rest upon the results

obtained from a single proteid, for I have at various times studied

also the primary products formed in the cleavage of casein, elastin,

zein, and other proteids by the action of hot dilute acid, and in all

cases have obtained evidence of the formation of several proteose-like

bodies, as well as of true peptones.

By the action of more powerful hydrolytic agents, such as boiling

hydrochloric acid to which a little stannous chloride has been added

to prevent oxidation, the proteid molecule may be completely broken

down into simple decomposition products, of which leucin, tyrosin,

aspartic acid, glutamic acid, glucoprotein, lysin, and lysatinin are

typical examples.[91] In other words, by this and other methods of

treatment, which we cannot take time to consider, we can easily break

down the albumin-molecule completely into bodies which, as we shall see

later on, are typical end-products of trypsin-proteolysis, and which

are far removed from the original proteid. But, as we have seen, even

the primary bodies formed in the less profound hydrolysis induced by

superheated water, do not show the composition of the mother-proteid.

Hydration and cleavage leave their marks upon the products, and thereby

we know that solution of the proteid is the result of something more

than a mere rearrangement of the atoms in the molecule.

[91] Hlasiwetz und Habermann, Ann. Chem. u. Pharm., Band 169, p. 150.

Also Drechsel, Du Bois-Reymond’s Archiv f. Physiol., 1891, p. 255.

Further, we are to remember that boiling dilute acid and superheated

water tend to produce a cleavage along specific lines; viz., a cleavage

into the anti- and hemi-groups of the molecule, and as representatives

of these groups we may, in the hydration of every native proteid, look

for two distinct rows of closely related substances.

In digestive proteolysis it will be our purpose to show that cleavage

of much the same order occurs, not necessarily resulting, however,

in the formation of identically the same products, but certainly

accompanied with the production of bodies belonging to the hemi- and

anti-groups, although they may be less sharply separated from each

other than in the cleavage with dilute sulphuric acid.

The body originally described as hemialbumose, and identified as a

product of every gastric digestion, is now known to be a mixture of

closely related substances ordinarily spoken of as albumoses,[92]

or generically as proteoses. These are primary products in the

digestion of every form of proteid matter, intermediate between the

mother-proteid and the peptone which results from the further action

of the proteolytic enzymes. Associated with the hemialbumoses are

corresponding antialbumoses, coming from the anti-half of the proteid

molecule, and differing from their neighbors, the hemi-bodies,

mainly in their behavior toward the ferment trypsin. Thus, we have

the counterpart of the many bodies described by Meissner, although

now arranged systematically and on the basis of structural and other

differences not thought of in his day.

[92] Kühne und Chittenden: Ueber Albumosen, Zeitschr. f. Biol., Band

20, p. 11.

By the initial action of pepsin-acid, proteids are first transformed

into acid-albumin or syntonin, then, by the further action of the

ferment, this body is changed into the primary proteoses, proto and

heteroproteose, of each of which there must be two varieties, a hemi

and an anti. These may then undergo further transformation into what

is known as a secondary proteose, viz., deuteroproteose, of which

there must likewise be two varieties, corresponding to the hemi- and

anti-groups respectively. By continued proteolytic action there results

as the final product of gastric digestion peptones; approximately, an

equal mixture of so-called hemipeptone and antipeptone, generally known

as amphopeptone. Such a peptone exposed to the proteolytic action of

trypsin should obviously break down in part into simple crystalline

bodies, leaving a residue of true antipeptone. In truth, this is

exactly what does happen when the peptone resulting from gastric

digestion is warmed with an alkaline solution of trypsin. The so-called

hemipeptone quickly responds to the action of the pancreatic ferment,

and is converted into other products, while the so-called antipeptone

resists its action completely, thus giving results in harmony with our

general conception of the proteid molecule.

ALBUMIN MOLECULE.

(_Hemi-groups._ _Anti-groups._)

║ ╲ ╱ ║ ║

║ ╳ ║ ║

║ ╱ ╲ ║ ║

Protoalbumose Heteroalbumose Antialbumid

(amphoalbumose) (amphoalbumose) ║

║ | | ║ ║

Deuteroalbumose Deuteroalbumose Deuteroalbumose

(amphoalbumose) (amphoalbumose) (antialbumose)

║ | | ║ ║

Amphopeptone Amphopeptone Antipeptone

On the basis of these facts, and others not yet mentioned, we may

accept provisionally, at least, the above schematic view, suggested

in part by Neumeister,[93] of the general line of proteolysis as

it occurs in pepsin-digestion; a view which clearly expresses the

significant relationship of the hemi- and anti-groups in the proteid

molecule.

[93] Zur Kentniss der Albumosen, Zeitschr. f. Biol., Band 23, p. 391.

The dark and light lines in this scheme are intended to represent the

relative share which the hemi- and anti-groups take in the formation

of the individual bodies. Thus, we see that protoproteoses have their

origin mainly in the hemi-groups of the molecule, although, as the

fine line indicates, anti-groups are somewhat concerned in their

construction. Heteroproteoses, on the other hand, come mainly from

the anti-groups, but still some hemi-groups have a part in their

structure. As previously stated, these two primary proteoses by further

hydrolytic action may be transformed into secondary products; viz.,

into deuteroproteoses, but, as the above scheme indicates, the two

deutero bodies will be more or less unlike in their inner nature. In

one sense, they are both amphodeuteroproteoses, but they necessarily

differ in the proportion of hemi- and anti-groups they contain. By

the still further action of pepsin-acid, the deutero bodies may be

changed, in part at least, into peptone, _i. e._, into amphopeptone,

although, as Neumeister has pointed out, protoproteose tends to yield

an amphopeptone in which the hemi-groups predominate, while the peptone

coming from heteroproteose contains an excess of anti-groups. Moreover,

in the gastric digestion of any simple proteid a certain number of

anti-groups are split off in the form of antialbumid, a body which is

only slowly digestible in pepsin-acid. By the very powerful proteolytic

action of a strong gastric juice, however, antialbumid may be somewhat

digested, and is then transformed into antideuteroalbumose, which in

turn may be eventually changed into antipeptone.

From these statements it is evident that a given proteid exposed to

pepsin-proteolysis may give rise to a large number of products; in

fact, to a far larger number than is implied by the names in the above

scheme. Thus, at first glance you would be inclined to say there can

be only three deuteroalbumoses, for example; one, a pure antibody, the

other two, amphoalbumoses, differing from each other simply in their

content of hemi- and anti-groups. It must be remembered, however, that

the inner constitution of these bodies, as implied by the relative

proportion of the above groups, may vary to almost any extent. Thus,

every variation in the number of anti-groups split off from the

original albumin molecule to form antialbumid means just so much of

a change in the relative proportion of hemi- and anti-groups entering

into the structure of both primary and secondary albumoses. Hence, as

you can see, digestive proteolysis, even in gastric digestion, is a

somewhat complex process. We have to deal not only with a number of

bodies superficially unlike, as the primary and secondary proteoses

and peptones, but these bodies may show marked variations in structure

dependent upon the exact conditions attending their formation.

Evidently, the complexities attending digestive proteolysis are

connected primarily with the complex nature of the proteids themselves,

while proteolysis, as a process, is made possible through the natural

tendency of the proteids to undergo hydration and cleavage.

LECTURE II.

PROTEOLYSIS BY PEPSIN-HYDROCHLORIC ACID, WITH A CONSIDERATION OF THE

GENERAL NATURE OF PROTEOSES AND PEPTONES.

PROTEOLYSIS BY PEPSIN-ACID.

On Digestive Proteolysis Being the Cartwright Lectures for 1894 · 第 3 / 11 段

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