Trypsin Preparation Research Articles

The Nonspecific Nature of the Carbohydrate Portion of Horse Pseudoglobulin

Summary When recrystallized preparations of pepsin, trypsin, and chymotrypsin are allowed to act on horse pseudoglobulin, the loss of specificity of the protein closely parallels destruction of protein both being completely effected by pepsin. The polysaccharide present to the extent of 3.7 per cent in horse globulin, whether prepared by the method of Rimington, using baryta, or by a method which would preserve any acetyl groups originally present, gives neither specific precipitative nor inhibitive reactions with homologous antiserum. It is concluded that the polysaccharide of horse globulin has no specificity in the sense that the pneumoccoccal polysaccharides have, the specificity of the globulin being a property of the molecule as a whole.

FORMATION OF TRYPSIN FROM TRYPSINOGEN BY AN ENZYME PRODUCED BY A MOLD OF THE GENUS PENICILLIUM

1. A powerful kinase which changes trypsinogen to trypsin was found to be present in the synthetic liquid culture medium of a mold of the genus Penicillium. 2. The concentration of kinase in the medium is increased gradually during the growth of the mold organism and continues to increase for some time even after the mold has ceased growing. 3. Mold kinase transforms trypsinogen to trypsin only in an acid medium. It differs thus from enterokinase and trypsin which activate trypsinogen best in a slightly alkaline medium. 4. The action of the mold kinase in the process of transformation of trypsinogen is that of a typical enzyme. The process follows the course of a catalytic unimolecular reaction, the rate of formation of a definite amount of trypsin being proportional to the concentration of kinase added. The ultimate amount of trypsin formed, however, is independent of the concentration of kinase used. 5. The formation of trypsin from trypsinogen by mold kinase is not accompanied by any measurable loss of protein. 6. The temperature coefficient of formation of trypsin from trypsinogen by mold kinase varies from Q(5-15) = 1.70 to Q(25-30) = 1.25 with a corresponding variation in the value of micro from 8100 to 4250. 7. Trypsin formed from trypsinogen by means of mold kinase is identical in crystalline form with the crystalline trypsin obtained by spontaneous autocatalytic activation of trypsinogen at pH 8.0. The two products have within the experimental error the same solubility and specific activity. A solution saturated with the crystals of either one of the trypsin preparations does not show any increase in protein concentration or activity when crystals of the other trypsin preparation are added. 8. The Penicillium mold kinase has a slight activating effect on chymo-trypsinogen the rate being only 1-2 per cent of that of trypsinogen. The activation, as in the case of trypsinogen, takes place only in an acid medium. 9. Mold kinase is rapidly destroyed when brought to pH 6.5 or higher, and also when heated to 70 degrees C. In the temperature range of 50-60 degrees C. the inactivation of kinase follows a unimolecular course with a temperature coefficient of Q(10) = 12.1 and micro = 53,500. The molecular weight of mold kinase, as determined by diffusion, is 40,000.

The presence of a kinase of amylase in trypsin preparation

The presence of a kinase of amylase in trypsin preparation

Formaldehyde Inhibition of Tryptic and Peptic Digestion of Egg White.

In connection with a study of the action of formaldehyde on certain bacterial suspensions, parallel observations were made of its effect on trypsin and pepsin. Little work has been reported on the influence of formaldehyde on tryptic and peptic digestion of proteins. Johannessohn found that preparations of trypsin vary in their susceptibility to this aldehyde; activity of one preparation was unaffected by 20 hours standing with 1% formaldehyde, while that of another was inhibited by 1/20% formaldehyde. He also reported that pepsin was not inactivated by 10% formaldehyde in 24 hours. In our experiments, however, formaldehyde in low concentrations had a marked inhibitory effect on the action of both trypsin and pepsin on egg-white. Complete inactivation was not accomplished, however, by the presence of 4% formaldehyde as shown by 18 hour digestion. (Table I.) Two solutions of raw egg white containing 0.25% and 2.5% protein respectively and 0.4% trypsin were divided into 10 cc. volumes, and each series treated with varying concentrations of formaldehyde. The reaction was adjusted to pH 7.4 and the mixtures allowed to digest at 37-40° for 18 hours. Similar concentrations of macerated coagulated egg white were digested with 0.1% pepsin at pH 2.5. At the end of the digestion period the liquids were neutralized and the extent of digestion determined by means of Sorensen's formol titration method.

Rate of Ammonia Liberation in Tryptic and Peptic Digestion of Casein

Summary1. In tryptic digestion the liberation of ammonia was due to an enzymic activity associated with the trypsin preparation used, whereas in peptic digestion the ammonia liberation was due to the acidity only. 2. The more rapid liberation at first in a pepsin digest than in the control can be explained on the basis of the physical atid chemical change in the substrate due to peptic proteolysis. 3. Kidney-extract did not hasten ammonia liberation. The aminolytic and amidolytic activity in the extract was high and seemed to follow the same course as with trypsin. 4. The concentration of antiseptic used under the conditions described did not retard either activity.The author wishes to express her appreciation to Professor F. C. Koch for his helpful criticisms and suggestions.