Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.9 (enterokinase)
 675 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thrombokinase of the blood, while resembling enterokinase in its role of activator, is more closely analogous to trypsin in its intrinsic origin. It probably arises from a plasma precursor; but it is different from plasmin (fibrinolysin). Like trypsin, thrombokinase can activate prothrombin without the aid of other factors; however, it is potentiated by platelets plus calcium. Unlike certain tissue "thromboplastins," it does not sediment appreciably in 2 hours at 85,000 g. Like trypsin, it hydrolyzes p-toluenesulfonylarginine methyl ester (TAMe). Chromatography on DEAE-cellulose separated thrombin from thrombokinase. The TAMe esterase associated with the thrombokinase fractions was largely suppressed by soybean trypsin inhibitor, while that associated with the thrombin fractions was not. Highly purified thrombokinase was used as starting material; and thrombokinase was eluted in the last major protein band. Under these conditions stepwise elution was as effective as gradient in leading to further purification. The product of 199 liters of bovine plasma was chromatographed in 1 day; and the specific activity was comparable to that attained previously by repeated electrophoretic fractionations. The assembled data suggest that the thrombokinase protein may be approaching homogeneity.
J Gen Physiol 1962 Mar
PMID:Thrombokinase of the blood as trypsin-like enzyme. 1403 95

A method is described for isolating a crystalline protein of high tryptic activity from beef pancreas. The protein has constant proteolytic activity and optical activity under various conditions and no indication of further fractionation could be obtained. The loss in activity corresponds to the decrease in native protein when the protein is denatured by heat, digested by pepsin, or hydrolyzed in dilute alkali. The enzyme digests casein, gelatin, edestin, and denatured hemoglobin, but not native hemoglobin. It accelerates the coagulation of blood but has little effect on the clotting of milk. It digests peptone prepared by the action of pepsin on casein, edestin or gelatin. The extent of the digestion of gelatin caused by this enzyme is the same as that caused by crystalline pepsin and is approximately equivalent to tripling the number of carboxyl groups present in the solution. The activity of the preparation is not increased by enterokinase. The molecular weight by osmotic pressure measure is about 34,000. The diffusion coefficient in (1/2) saturated magnesium sulfate at 6 degrees C. is 0.020 +/-0.001 cm.(2) per day, corresponding to a molecular radius of 2.6 x 10(-7) cm. The isoelectric point is probably between pH 7.0 and pH 8.0. The optimum pH for the digestion of casein is from 8.0-9.0. The optimum stability is at pH 1.8.
J Gen Physiol 1932 Nov 20
PMID:CRYSTALLINE TRYPSIN : II. GENERAL PROPERTIES. 1987 6

A new crystalline protein, chymo-trypsinogen, has been isolated from acid extracts of fresh cattle pancreas. This protein is not an enzyme but is transformed by minute amounts of trypsin into an active proteolytic enzyme called chymo-trypsin. The chymo-trypsin has also been obtained in crystalline form. The chymo-trypsinogen cannot be activated by enterokinase, pepsin, inactive trypsin, or calcium chloride. There is an extremely slow spontaneous activation upon standing in solution. The activation of chymo-trypsinogen by trypsin follows the course of a monomolecular reaction the velocity constant of which is proportional to the trypsin concentration and independent of the chymotrypsinogen concentration. The rate of activation is a maximum at pH 7.0-8.0. Activation is accompanied by an increase of six primary amino groups per mole but no split products could be found, indicating that the activation consists in an intramolecular rearrangement. There is a slight change in optical activity but no change in molecular weight. The physical and chemical properties of both proteins are constant through a series of fractional crystallizations. The activity of chymo-trypsin decreases in proportion to the destruction of the native protein by pepsin digestion or denaturation by heat or acid. Chymo-trypsin has powerful milk-clotting power but does not clot blood plasma and differs qualitatively in this respect from the crystalline trypsin previously reported. It hydrolyzes sturin, casein, gelatin, and hemoglobin more slowly than does crystalline trypsin but the hydrolysis of casein is carried much further. The hydrolysis takes place at different linkages from those attacked by trypsin. The optimum pH for the digestion of casein is about 8.0-9.0. It does not hydrolyze any of a series of dipeptides or polypeptides tested. Several chemical and physical properties of both proteins have been determined.
J Gen Physiol 1935 Mar 20
PMID:CRYSTALLINE CHYMO-TRYPSIN AND CHYMO-TRYPSINOGEN : I. ISOLATION, CRYSTALLIZATION, AND GENERAL PROPERTIES OF A NEW PROTEOLYTIC ENZYME AND ITS PRECURSOR. 1987 56

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.
J Gen Physiol 1938 May 20
PMID:FORMATION OF TRYPSIN FROM TRYPSINOGEN BY AN ENZYME PRODUCED BY A MOLD OF THE GENUS PENICILLIUM. 1987 69

A solution of crystalline trypsinogen in dilute buffer containing a trace of active trypsin when allowed to stand at pH 5.0-9.0 and 5 degrees C. is gradually transformed partly into trypsin protein and partly into an inert protein which can no longer be changed into trypsin either by enterokinase or mold kinase. During the process of formation of trypsin and inert protein the ratio of the concentrations of the two products in any reaction mixture remains constant and is independent of the original concentration of trypsinogen protein. This ratio varies, however, with the pH of the solution, the proportion of trypsin formed being greater in the acid range of pH. The experimental curves for the rate of formation of trypsin, as well as for the rate of formation of inert protein are symmetrical S shaped curves closely resembling those of simple autocatalytic reactions. The kinetics of formation of trypsin and inert protein can be explained quantitatively on the theoretical assumptions that both reactions are of the simple unimolecular type, that in each case the reaction is catalyzed by trypsin, and that the rate of formation of each of the products is proportional to the concentration of trypsin as well as to the concentration of trypsinogen in solution.
J Gen Physiol 1939 Jan 20
PMID:EFFECT OF THE FORMATION OF INERT PROTEIN ON THE KINETICS OF THE AUTOCATALYTIC FORMATION OF TRYPSIN FROM TRYPSINOGEN. 1987 5

Crystalline trypsinogen is most readily and completely transformed into trypsin by means of enterokinase in the range of pH 5.2-6.0 at 5 degrees C. and at a concentration of trypsinogen of not more than 0.1 mg. per ml. The action of enterokinase under these conditions is that of a typical enzyme. The process follows closely the course of a catalytic unimolecular reaction, the rate of formation of trypsin being proportional to the concentration of enterokinase added and the ultimate amount of trypsin formed being independent of the concentration of enterokinase. The catalytic action of enterokinase on crystalline trypsinogen in dilute solution at pH more alkaline than 6.0 and in concentrated solution at pH even slightly below 6.0 is complicated by the partial transformation of the trypsinogen into inert protein which can no longer be changed into trypsin even by a large excess of enterokinase. This secondary reaction is catalyzed by the trypsin formed and the rate of the reaction is proportional to the concentration of trypsin as well as to the concentration of trypsinogen in solution. Hence under these conditions only a small part of the trypsinogen is changed by enterokinase into trypsin while a considerable part of the trypsinogen is transformed into inert protein, the more so the lower the concentration of enterokinase used. The kinetics of the formation of trypsin by means of enterokinase when accompanied by the formation of inert protein can be explained quantitatively on the theoretical assumption that both reactions are of the simple catalytic unimolecular type, the catalyst being enterokinase in the first reaction and trypsin in the second reaction.
J Gen Physiol 1939 Mar 20
PMID:FORMATION OF TRYPSIN FROM CRYSTALLINE TRYPSINOGEN BY MEANS OF ENTEROKINASE. 1987 12

A concentrated solution of purified enterokinase is conveniently prepared from the fluid contents of pigs' duodena by means of fractional precipitation with ammonium sulfate under the proper pH conditions.
J Gen Physiol 1939 Mar 20
PMID:PURIFICATION AND CONCENTRATION OF ENTEROKINASE. 1987 13

1. Methods for the preparation and partial purification of streptococcal fibrinolysin are described. 2. The lysis of fibrin clots in the presence of streptococcal fibrinolysin is associated with proteolysis of the fibrin. Digestion is due to an enzyme normally present in serum or plasma in an inactive state, which is activated by fibrinolysin. Fibrinolysin alone has no demonstrable proteolytic activity. 3. The lysin factor-fibrinolysin system brings about proteolysis of other proteins such as gelatin or casein, in addition to fibrin and fibrinogen. 4. It is suggested that lysin factor exists in serum or plasma as a zymogen, and that it is activated by fibrinolysin, a kinase, in a manner similar to the activation of trypsinogen by enterokinase or the mold kinase of Kunitz (1938).
J Gen Physiol 1945 Mar 20
PMID:STREPTOCOCCAL FIBRINOLYSIS: A PROTEOLYTIC REACTION DUE TO A SERUM ENZYME ACTIVATED BY STREPTOCOCCAL FIBRINOLYSIN. 1987 27

1. Fibrinolysin-activated lysin factor and chloroform-activated serum protease of serum and plasma are one and the same enzyme, differing only in their mode of activation. 2. The enzyme as it normally occurs in serum or plasma is not inactive because of combination with serum inhibitor. It is present as an inactive precursor or zymogen and may be activated from this state by streptococcal fibrinolysin. 3. The activation of serum protease by streptococcal fibrinolysin is a catalytic reaction, analogous to the kinase activation of trypsinogen by enterokinase. Treatment of serum or plasma with chloroform apparently results in removal of serum inhibitor which may allow autocatalytic activation of the serum protease. 4. The serum enzyme differs from trypsin in its pH of optimum activity, in its reactions with specific protease inhibitors, and in its action on casein. 5. A revised nomenclature for the serum enzyme system is suggested which more accurately describes its properties than the terms in current use.
J Gen Physiol 1945 Jul 20
PMID:A PROTEOLYTIC ENZYME OF SERUM: CHARACTERIZATION, ACTIVATION, AND REACTION WITH INHIBITORS. 1987 36

Fusion gene consisting of dextran-binding domain from Leuconostoc mesenteroides subsp. Mesenteroides (DBD) and human recombinant interferon-beta (IFN-beta) incorporated between the nucleotide sequence encoding for the recognition site of human enteropeptidase (DDDDK) was installed and constructed in Escherichia coli. The overproducing strain of the chimeric protein DBD-IFN-beta consisting of the IFN-beta, spacer including 10 GS-repeats, human enteropeptidase recognition site, and dextran-binding domain from Leuconostoc mesenteroides was constructed. Free human recombinant interferon-beta was obtained as a result of treatment of the chimeric protein DBD-IFN-beta immobilized on sephadex G-25 with human enteropeptidase. The ability of free and immobilized protein to protect human cells from viral infection was demonstrated. The developed approach can be used for purification of the recombinant proteins with different biological activity and possible construction of new immunostimulating and antiviral drugs, growth factors, anti-cancer drugs, etc.
Mol Gen Mikrobiol Virusol 2009
PMID:[Human recombinant interferon-B constructed on the basis of affinity-binding domain technology]. 2001 62


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