Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.1 (chymotrypsin)
 10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Eleven pigs were fitted with pancreatic and duodenal fistulae, and pancreatic juice collected permanently. Amylase, chymotrypsin, lipase and total proteins were determined in juice collected within 2 and 6 hours after different test-meals or intraduodenal loads of glucose and maltose. In the pancreatic juice of pigs adapted to a high-lipid diet and submitted to a high-carbohydrate test-meal the activity of amylase was increased by 50%. When the consumption of the high-lipid meal was associated with an intraduodenal load of 100 g of glucose all the enzyme activities were stimulated when compared to the effect of meal alone, but only the activity of amylase was significantly increased (+ 82%). In the juice of pigs adapted to a balanced diet and submitted to intraduodenal loads of 150 ml of water, 50 g of glucose, 50 g of maltose and 150 g of maltose, the enzyme activities remained almost constant with the load of water and 50 g of maltose but with 50 g of glucose and 150 g of maltose loads, amylase activity was increased by 20% and 30% respectively. It is suggested, that the exocrine pancreas of the pig adapts itself rapidly to the changes in the size of the intestinal pool of starch hydrolysis products.
 ...
PMID:Pancreatic exocrine secretion in the pig following test meals of different composition and intra-duodenal loads of glucose and maltose. 47 30

The purpose of the study was to examine the secretory response of the exocrine pancreas in man to various doses of the synthesised decapeptide Caerulein (Takus), 5, 10 and 20 ng/kg Caerulein injected intravenously during an infusion of 0,5 CU/kg/h Secretin (GIH) produced a linear increase of enzyme secretion (amylase, lipase, trypsin and chymotrypsin) and also an increase in the water and bicarbonate secretion of the pancreas which is induced by Secretin. The injection of 40 ng/kg Caerulein led to no further increase of the ecbolic function. The intravenous injection of 1 Ivy dog unit (IDU/kg and 20 and 40 ng/kg Caerulein have an identical effect on the exocrine pancreas, there were no statistic differences.
 ...
PMID:[Effect of caerulein on the exocrine pancreas function in man; examinations of dose effects and comparisons with the effect of cholecystokinin/pankreozymin (author's transl)]. 49 1

There was studied the solid-state enzyme reaction of specific substrate N-succinyl-L-phenylalanine-p-nitroanilide hydrolysis in contact with alpha-chymotrypsin (Cht). It is shown that product yield is dependent on hydration of the protein. The product is formed only when the relative pressure of water vapours (p/ps) was higher than certain magnitude (p/ps) crit; which depends on the amount of the salt in the sample: the higher the salt concentration the lesser the (p/ps) crit value. It is suggested that the counter-ions may interact with some of primary hydration sites of the Cht molecule. Because of that for the formation of the active Cht conformation is enough to bind lesser number of water molecules than in salt-free samples. But in the presence of salt excess in Cht sample it is necessary to bind of the protein surface at least yields to 80 mol H2O/mol Cht.
 ...
PMID:[Solid-state enzymatic reactions. II. Chymotrypsin hydrolysis of N-succinyl-L-phenylalanine n-nitroanilide]. 58 2

The enthalpies (deltaH) and entropies (deltaS) of the interaction of water with alpha-chymotrypsin were evaluated from multitemperature sorption isotherms in the temperature range 283--313 K, determined in a fully automatized, computer controlled sorption apparatus. The temperature dependence of deltaH and deltaS shows a marked anomaly in the temperature range 295--298 K. The experimental results are interpreted by a phase transition of the enzyme protein, and by the existence of a low- and high-temperature conformer of alpha-chymotrypsin below and above the transition region. The two conformers differ significantly in their water binding energetics, as proved by two F-tests based on analyses of variance. The deltaH and deltaS versus water content functions of the high and low temperature conformer show markedly different anomalies at and below 70 mol H2O per mol protein. This water content corresponds closely to the monolayer volume vm, (as defined by Brunauer, Emmett and Teller). The protein surface covered by one water-monolayer, agrees well with the polar and charged surface area of chymotrypsin, computed from X-ray data. The experimental results suggest that the interaction of the first water-monolayer with the protein surface induces major conformational changes. The energetic contributions of these structural changes dominate the deltaH and deltaS terms below vm, giving rise to the anomalies observed. Above this water content, their influence is drastically reduced, and the isosteric quantities are predominantly determined by the water binding process per se. This process is possibly related to the pronounced enthalphy-entropy compensation pattern exhibited by the deltaH and deltaS terms. A more detailed analysis and discussion of this compensation effect will be given.
 ...
PMID:Thermodynamic studies of the interaction of alpha-chymotrypsin with water. I. Determination of the isosteric enthalpies and entropies of water binding to the native enzyme. 64 17

alpha-Chymotrypsin preparations covalently bound by Shiff bases with water soluble oxidated dextran and alginate are obtained to study the effect of charged and neutral matrices on the enzymes stability under their modification by polymers. Water soluble enzyme preparations show a catalytic activity and have a slightly enhanced thermostability. Thermostability of alpha-chymotrypsin modified by a negatively charged polymer is increased owing to the reducing of activation entropy of the denaturation reaction, while the increase of the stability of neutral polymer (dextran) modified enzyme is due to the increase of activation enthalpy of the denaturation reaction.
 ...
PMID:[Effect of soluble matrix on the stability of modified alpha-chymotrypsin]. 66 9

An inhibitor of papain and other SH-proteases was purified 520-fold from human epidermis extracts by acetone fractionation, heat treatment, papain-Sepharose affinity chromatography, and Sephadex G-50 chromatography. The purified inhibitor had a molecular weight of 12,600 and contained no hexose, as tested by the anthrone reaction. The inhibitor survived in a boiling water bath, in 5% trichloroacetic acid, 20 mM Na3PO4 (pH 12.1) and 4 M NH4OH (pH 11.9). By isoelectric focusing 2 major activity peaks with pI's of 4.6 and 4.8, and a minor peak with a pI of 4.9 was fractioned, and 3 corresponding protein bands were seen after analytical isoelectric focusing. Immunization of rabbits with the purified inhibitor yielded a highly specific anti-inhibitor serum. The purified inhibitor inhibited papain, ficin, human cathepsins B and C, and slightly inhibited bromelain. No inhibition of serine proteases (bovine trypsin and chymotrypsin A, porcine elastase) or an acid protease (human cathepsin D) was observed. Evidence was obtained that the inhibitor formed a complex with both dithiothreitol-activated papain and enzymatically inactive mercuripapain.
 ...
PMID:Purification and some characteristics of the human epidermal SH-protease inhibitor. 68 77

Electrostatic effects dominate many aspects of protein behavior. When polypeptide chains fold up, most polar side chains seek the exterior, where they can be solvated. Water bound in the interior has been found between the domains of enzymes of the chymotrypsin family, and between the subunits of hemoglobin and tobacco mosaic virus protein. Assembly of this protein from disk to virus is triggered by electrostatic interactions between neighboring subunits. Lysozyme stabilizes the constellation of charges involved in the transition state of its substrate by both permanent and induced dipoles. All factors that lower the oxygen affinity of hemoglobin act by strengthening the salt bridges that constrain its quaternary deoxy (T) structure. Enzymes of thermophile bacteria owe their extra stability mostly to additional salt bridges. The rate of denaturation of hemoglobins by alkali is determined by the ionization of internal side chains with pK's of about 12.
 ...
PMID:Electrostatic effects in proteins. 69 8

We describe the preparation and some of the properties of heparin-bound alpha-chymotrypsin that were obtained via activation of heparin with water-soluble carbodiimide. Immobilized enzyme has unchanged kinetic characteristics toward low-molecular- weight and macromolecular substrates. The heparin-bound enzymes could have a wide range of medical applications.
 ...
PMID:Enzyme immobilization on heparin. 70 Dec 96

Differential enthalpies (deltaH) and entropies (deltaS) of the interaction of water with a high and low temperature conformer of alpha-chymotrypsin were determined previously by multitemperature sorption measurements. The changes in (deltaH) and (deltaS) with water content of the protein were found to show a pronounced compensation pattern. It is known that van 't Hoff data may exhibit enthalpy-entropy compensation, which is entirely due to statistical error propagation. To discriminate between artifactual and significant compensation, the experimental results are analyzed by statistical methods. The results of two different statistical analyses show that a linear, chemically caused compensation effect can be established for the interaction of water with both chymotrypsin conformers. The compensation temperature beta = deltaH/deltaS was found to be 433 +/- 22 K. The compensation effect is detectable only in the water content range above the monolayer volume (upsilonm), computed by the Brunauer, Emmett and Teller equation. This result is discussed in terms of a monolayer hydration mechanism, formulated on the basis of previous thermodynamic results: The interaction of the first water monolayer with the charged and polar surface area of the dry protein, largely stabilizes its tertiary structure. Further water addition then occurs to a practically invariable protein surface. According to this mechanism (which ensures a maximum of conformational stability with a minimum of hydration water), large conformational changes can be expected to occur mainly in the monolayer water content range. This expectation is confirmed by extra-thermodynamic data (infrared and X-ray measurements). The thermodynamic quantities of the sorption process are thus governed by conformational effects below upsilonm. Above the monolayer water content range, however, the water binding process per se strongly predominates. The deltaH/deltaS compensation effect established for this water content range, is thus attributable to phase transitions of water molecules from the gas (or liquid) phase to the protein-bound state (or vice versa). A possible relationship between the linear compensation effect established in this study, and the compensation phenomenon observed in reactions in aqueous solution is discussed.
 ...
PMID:Thermodynamic studies of the interaction of alpha-chymotrypsin with water. II. Statistical analyses of the enthalpy-entropy compensation effect. 70 66

The heavy water (D2O) has been shown to induce the conformational transitions in trypsin, chymotrypsin and pepsin. The transfer of proteins from H2O into D2O results a change in their sensitivity to UV-light. An increase in sensitivity to the irradiation at 248 nm and a decrease in sensitivity to the irradiation at 280 nm were observed. The quantum yield of chromophore photolysis (for cystyne and tryptophan) is correspondingly changed. However, although the quantum yield of sensitized reduction of cystine by solvated electrons photochemically ejected from the aromatic acid residues during irradiation at 280 nm increases instead of a rise a drop in the quantum yield of protein inactivation is registered. The data obtained are discussed in terms of importance of solvated shell for conformational stability of proteins. The solvated electrons are suggested to be transfered mainly to nonessential disulfide bridges within trypsin molecule. Rupture of these bonds does not result in trypsin inactivation.
 ...
PMID:[Influence of heavy water (D20) on the conformation and UV-sensitivity of proteins]. 80 85


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>