Albumoses primary

Kiihne and Chittenden have distinguished two classes of albumoses primary albumoses, which precipitate by NaCl saturation in neutral media, and the secondary albumoses or deutero-albumoses, which do not precipitate by NaCl saturation except in acid solution, and then incompletely. Moreover, primary albumoses are divided into ketero-albumoses, insoluble in pure cold water, but soluble in dilute salt solutions, and, consequently, precipitable by dialysis, and proto-albumoses, soluble in pure water and dilute salt solutions. 

Proto-albumoses (Primary albumoses) Hetero-albumoses... 

Primary albumoses, which correspond closely to those... 

By changing the reaction of the medium, different results are obtained, which often furnish useful information as to the nature of proteins under consideration. Albumin is not pre-dpitated from its solution by addifying with acetic add, or by saturating its neutral solution with sodium chloride. But if, after having saturated the solution of albumin with NaCl, it is then addified with acetic add, a predpitate is obtained. The same phenomenon occurs in predpitating albumose with sodium chloride. When a solution of primary albmnose is half saturated with sodimn chloride, there is no predpitation, but the predpitate appears as soon as the reaction of the liquid is made add. The predpitate thus obtained is hetero-albumose. 

The liquid, free from the first fraction, is filtered. To obtain the second fraction, add volume of the salt solution the precipitate is washed with a salt solution, f saturated, is redissolved several times in water, and each time is reprecipitated with the I saturated solution The third fraction is obtained when the filtrate from the second fraction is saturated with powdered ammonium sulphate. The fourth fraction precipitates when to the filtrate from the third fraction is added iV of a volume of dilute sulphuric acid, saturated with ammoiiium sulphate. To obtain a complete precipitate, allow this acidulated liquid to settle for two days wash the precipitate with a saturated and acidified solution of sulphate, and, finally, purify imder conditions similar to those used for the purification of the preceding fractions. The fifth fraction remains in solution in the liquid resulting from the four preceding fractions. The first fraction is given the name primary albumose fractions 2, 3, 4, the names detUero-albumoses A, B, C the fifth is peptone. 

The- interval between the higher limit of a fraction and the lower limit of the following fraction is everywhere very-sharp, and these limits cannot be confused. On the other hand, the corresponding limits differ little from one substance to another. It is only for the lower limit of primary albumose that we observe spaces as great as 2.6 to 4.2. This result can be explained, either by a difference in the nature of the same fraction coming from different substances, or more simply by the d ee of purity of the albuminoid substances used. 

This ascending and descending progress is found in each of the three deutero-albumoses. Furthermore, we can assert that the different deutero-albumoses are not produced exclusively at the expense of the primary albumose in fact, between the 4th and 8th hour the deutero-albumose B has increased from 8.58 to 15.53 6-95 being produced. In this same time, the primary albumose has lost only 5.39, hence, the deutero-albumose B is then formed in part from the deutero-albumose A. The same observation can be repeated with regard to the formation of the deutero-albumose C. Between the 24th and 48th hours, this fraction has increased from 3.52 to 7.0, while the primary albumose has diminished only from r.12 to 0.70. 

To have a clearer idea of the division of albumoses during the course of peptonization, we must determine the proportion of each fraction in the total quantity of albumose present at each sampling. The analysis of the samples taken shows that the four albumoses are found at each phase of the peptonization in different proportions. The primary albumose is the product which is formed most abundantly from the beginning of the action of the pepsin, but it disappears rather quickly, leaving a little residue, composed principally of hetero-albumose. The yield increases at the end, due to the transformation of the total albumose into peptone. The deutero-albumose A, while arriving at its maximum later than the primary albumose, disappears more quickly than the latter. The deutero-albumose... 

Length of eqieximent. hours. Primary albumose. Deuteco- albnmose A. Deutero- albumose B. Deutero- albumose C. 

The differences which are found in the proportions 6f the various albumoses, the very perceptible increase of albumose C, the diminution of primary albumose, the disappearance of deutero-albumose A, are additional data in favor of the existence of several varieties of albumoses for the same substance arbitrarily divided could not show such special properties. 

The sign + marks the presence of albumoses, the sign — the absence. These tests with egg-albumin indicate that, according to the concentration of acid and the duration of the experiment, we can get exclusively deutero-albumose B or primary albumose and deutero-albumose B, or again primary albumose and the deutero-albumoses A and B. 

These results are very favorable to the method of fractional precipitation. Primary albumose and deutero-albumose B are the products which are first formed deutero-albumose A appears as a secondary product and deutero-albumose C only as a final product of the reaction. This fraction is formed with difficulty in the presence of acids and is not met in appreciable quantity except in the last phases of peptonization. 

To determine the primary albumose in all the samples, 20 c.c. of liquid are taken, 0.4 c.c. of dilute sulphuric add added and 17 c.c. of a saturated solution of addihed zinc sulphate This is left standing 24 hours, then the precipitate is filtered and washed five times with a solution half saturated with zinc sulphate. 

Length of the action Primary albumose per 100 g of liquid, milligrams... 

If we compare the quantity of peptone formed from primary albumose with, that formed from the deutero-albumoses, we see that peptonization of the two products does not progress equally. Primary albumose peptonizes easily, while the transformation of the deutero-albumoses is much slower. After 12 hours of action, we get o 92 g. with primary albumose and 0.74 g. with deutero-albumoses. After 24 hours, we have i.i g. with primary albumose and o 89 g. with deutero-albumoses. We may then conclude that these two fractions are not identical. Furthermore, we may also conclude that the deutero-albumoses are not homogeneous, since the progress of peptonization of deutero-... 

Yet, it is quite true that the four albumoses thus obtained, though they manifest distinctive properties, should not be regarded as strict chemical individuals, but rather as different groupings of compounds. Thus, primary albumose is composed of proto-albumose and hetero-albumose, this last being characterized by the predpitate which it gives with cold nitric add, or with copper acetate and sulphate. In deutero-albumose A, Zunz distinguishes two fractions. Finally, deutero-albumose... 

Plastein was first obtained with the products of hydrolysis of nitrogenous matter under the influence of pepsin or trypsin, but the products formed by the moderate action of acids or alkalis can serve just as well. The products of advanced hydrolysis by trypsin or acids yield no plastein, or only a very little. According to Kurajeff, the different proteolytic enzymes do not act equally well in the same media. Papayotin gives an abundant deposit of plastein with secondary albumose and very little with primary albumose, while rennet, on the contrary, gives much plastein with the primary and little with the secondary. Below, according to Henriques, is the comparative action of enzymes on the different products of albuminoid hydrolysis ... 

Products Formed. — In the reactions involving pepsin it was seen that albumoses and peptones were produced as well as complex non-bimretic bodies not precipitated by phospho-tungstic acid but susceptible of crystallization. All these products of high molecular weight come from the partial hydrolysis of the albuminoid material. They also show the characteristics, more or less pronounced, of the substance from which they are derived. With trypsin, a much deeper effect is observed. Without doubt primary albumoses are still formed... 

Zunz has made similar observations in the case of albumoses. As is well known albumoses are decomposition products of e albumin and are produced dirring digestion. They are more closely related to albumin than are the peptones, and manifest great differences in diffusion in that primary albumoses diffuse with difficulty while the secondary albumoses diffuse easily. The primary albumoses are more easily precipitated by ammonium sulfate than are the secondary. To the primary albumoses belong heteroalbumoses soluble only in dilute salt solutions, protalbumoses soluble in pure water, and synalbumoses. The gold numbers found by Zunz for the three decomposition products are as follows ... 

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