Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.4.21.1 (chymotrypsin)
10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Chymotrypsin treatment of spinach chloroplast membranes does not change the electrophoretic mobility of either chlorophyll-protein complex 1 or 2. 2. The extraction of lipids with 80% acetone after treatment of the membranes with chymotrypsin reveals that the polypeptide components of both chlorophyll-protein complexes had been extensively digested. The extraction of carotenes with petroleum ether under the same conditions does not change the electrophoretic mobility of the chlorophyll-protein complexes. 3. Fluorescence polarisation studies of chlorophyll-protein complex 2 reveal that the chymotrypsin digestion of this complex does not result in changes of mutual orientation or distance apart of chlorophyll a, chlorophyll b or carotenoid. 4. Two polypeptide components have been detected after lipid extraction of electrophoretically purified chlorophyll-protein complexes 1 and 2. The SDS molecular weights are 24 000 and 27 000 for complex 2, and 68 000 and 64 000 for complex 1. 5. We conclude that chlorophyll performs an important structural function in both chlorophyll-protein complexes.
...
PMID:Evidence for a structural role for chlorophyll in chlorophyll-protein complexes. 50 98

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

Kinetic constants are reported for alpha-chymotrypsin- and Streptomyces griseus protease 3 (SGP3)-catalyzed amide hydrolysis of a number of peptide amides of varying substrate chain length. alpha-Chymotrypsin, but not SGP3, will hydrolyze rapidly specific acetyl amino acid amides. SGP3-catalyzed, but not alpha-chymotrypsin-catalyzed, hydrolysis is greatly stimulated by the presence of up to four amino acid residues N-terminal to the scissile bond of the substrate. The enzyme-substrate interactions utilized to promote hydrolysis, therefore, differ in these two enzymes, which, in other respects, show marked similarities. alpha-Chymotrypsin depends mainly on primary enzyme-substrate contacts, those with the amino acid residue (P1) whose carbonyl group forms part of the scissile bond, whereas SGP3 depends mainly on "secondary" enzyme-substrate contacts with amino acid residues (P2-P4) more remote from the scissile bond. A comparison with porcine elastase, a related serine protease, indicates that there is an inverse relation between the importance of primary and secondary enzyme substrate interactions in this family of enzymes. A rationale is proposed for this effect based on the observation that both types of enzyme-substrate interaction predominantly affect the rate constant for the acylation step of substrate hydrolysis.
...
PMID:The active centers of Streptomyces griseus protease 3 and alpha-chymotrypsin: enzyme-substrate interactions remote from the scissile bond. 81 24

alpha-Chymotrypsin (EC 3.4.21.1)-catalysed syntheses of peptides were performed with various N-acylated amino acid or peptide esters as donors, and amino acid derivatives, peptides or their derivatives as acceptors. Under optimal conditions the synthesis was almost quantitative. As acceptor nucleophiles, free amino acids or the ester derivatives were inadequate, but amino acid amides or hydrazides, di- or tri-peptides, or the amides, hydrazides and esters of the peptides were useful. The nucleophile specificity for synthesis was markedly similar to the leaving-group specificity in hydrolysis; hydrophobic or bulky amino acid residues were most effecient at both P1' and P2' positions [notation of Schechter & Berger (1967) Biochem. Biophys. Res. Commun. 27, 157-162], but L-proline as well as D-amino acid residues were the worst choices. The synthesis was further dependent on the solubility of the products synthesized; a higher yield of products was expected with lower solubility. As donor esters, good substrates were all useful. Accordingly, fragment condensation was possible by using N-acylated peptide esters and various peptides. The present study suggested that alpha-chymotrypsin may become a useful tool for peptide synthesis.
...
PMID:alpha-Chymotrypsin as the catalyst for peptide synthesis. 88 Feb 16

Water-soluble poly(N-vinylpyrrolidone) of molecular weight 10 000 was modified by hydrolysis of 5% of the gamma-lactam rings, and formation of the N-hydroxysuccinimidester. This activated polymer was bound covalently to trypsin (EC 3.4.21.4) and chymotrypsin (EC 3.4.21.1) to complexes of a molecular weight of about 150 000. The bound enzymes showed an increase in stability towards autolysis. Towards small molecular weight substrates the trypsin-poly (N-vinylpyrrolidone) conjugate showed an increase in specific activity of 1: 1.6, whereas the activity towards larger substrate was found to be only 20%. Chymotrypsin-poly(N-vinylpyrrolidone) showed decreased activity against small (50%) and large (7%) molecular weight substrates.
...
PMID:Preparation and properties of trypsin and chymotrysin coupled covalently to poly (N-vinylpyrrolidone). 88 41

alpha-Chymotrypsin is rapidly and completely inactivated by a series of halomethylated derivatives of dihydrocoumarins at pH 7 and 25 degrees. The inactivation is pH-dependent and optimal at neutral pH; it is also more or less complete depending on the excess of inhibitor with respect to the enzyme. These compounds are substrates for alpha-chymotrypsin and, during the catalytic process, a latent alkylating function of the reagent is activated at the active site of the enzyme and reacts with some vicinal nucleophilic amino acid residues. The stoichiometry of the reaction of the corresponding radioactive reagents with the enzyme is slightly superior to one, but one histidine residue of alpha-chymotropsin is mainly modified. This histidine is identified as histidine-57 by the diagonal peptide mapping method. In comparison with other reagents, the efficiency of these suicide substrates" and particularly that one of a derivative (compound 2) carrying a substrate-like side chain is found to be very high.
...
PMID:Inactivation of alpha-chymotrypsin by new bifunctional reagents: halomethylated derivatives of dihydrocoumarins. 88 29

Fecal chymotrypsin activity was measured in 128 samples from 93 persons; the titrimetric procedure (Haverback) was used. Distribution of values in 67 normal persons was slanted positively and was approximatively logarithmical. The lower limit of normal was 120 microgram/g stool. Falsely normal results were obtained in 23% of 45 stool samples from 26 patients with pancreatic insufficiency. Falsely pathological results were found in 3,6% of cases. When chymotrypsin was measured photometrically (Imondi) and when the normal limit was assumed to be 50 microgram/g stool according to the literature, a diagnosis of pancreatic insufficiency was confirmed only in 30% of all patients, and 44% of the results were falsely pathological. Chymotrypsin was measured with both methods in 66 samples; correlation of results was unsatisfactory and definitely lower results were obtained with the photometrical procedure. No correlation could be found as well when chymotrypsin activities were measured in stool homogenates on the one hand, and in the supernatant of stools after centrifugation on the other hand, by the titrimetrical or by the photometrical method. Results obtained titrimetrically as well as photometrically after activation of chymotrypsin in pancreatic juice correlated well; the same was true for 2 photometric procedures tested (Imondi, Nagel). Stimulation of the exocrine pancreas with one Lundh meal did not result in any significant increase of fecal chymotrypsin activity in 12 persons tested.
...
PMID:[Measurement of fecal chymotrypsin. Clinical and methodological aspects (author's transl)]. 92 84

The statistical availability of tryptophan and tyrosine residues with one ring face fully exposed to solvent was examined for two serine proteases and their derivatives by investigating the formation of charge transfer (CT) complexes between the aromatic donor residues of the protein and the acceptor 1-methylnicotinamide chloride. The availability of the ring face of one of the two exposed tryptophan residues in trypsin has been previously shown to be pH dependent and to parallel the acid side of the pH-activity profile of the enzyme. The present results indicate that, in diisopropylphosphoryl-trypsin (DIP-trypsin), this residue [which was identified as Trp-215 in native trypsin (chymotrypsin numbering)] is locked in a relatively rigid, pH-independent conformation with one ring face rotated out toward the solvent. In the zymogen and DIP-zymogen, the ring face is essentially unavailable. Chymotrypsin, like trypsin, has a pH-depent tryptophan residue available for complexation with the CT acceptor, but unlike trypsin, the pH dependence is apparently associated with dimerization of the enzyme. These and other data suggest this residue is the same as in the homologous trypsin structure, i.e., Trp 215, and that the ring face is mostly buried in the zymogen. Comparison of the crystal structure models of chymotrypsin and chymotrypsinogen shows that, as the specificity pocket opens up from its collapsed structure upon zymogen activation, the ring face of Trp-215 moves out and rotates relative to the surface of the enzyme in such a fashion as to become more accessible to solvent. These observations are in accord with the present CT results and provide additional support for the assignment of changes in Trp-215 availability to parallel changes in the conformation of the specificity pocket of these serine proteases. The present investigation also shows that, although a tryptophan ring face is partly exposed in DIP-chymotrypsin, its statistical availability more closely resembles that of the zymogen than the native enzyme. The reverse appears to be true for DIP-trypsin, which suggests the possibility that the specificity pocket in DIP-chymotrypsin may be partially collapsed while the catalytic residues are frozen in the conformation of the acyl-enzyme.
...
PMID:Flexibility in the specificity site of serine proteases. 94 68

Chymotrypsin output in the stools (u./24 hr.) has been calculated from analysis of single stool samples, using cuprous isothiocyanate as a continuous marker. The values thus calculated agreed favorably with those calculated from three-day stool collections. In 45 controls, with and without steatorrhea, chymotrypsin output was above 10,000 u./24 hr. In six patients with pancreatic insufficiency the values were considerably lower. In 10 patients with pancreatic disease without insufficiency the values were in the normal range. The method was found very useful in the diagnosis of pancreatic insufficiency. It was not sensitive enough to detect lesser degrees of pancreatic damage.
...
PMID:Chymotrypsin output in the stools in pancreatic and other diseases. 97 Mar 91

A method of microencapsulating of the proteolytic enzyme alpha-chymotrypsin into semi-permeable nylon membranes is worked out. The membrane is a polimer of 1,6-hexamethylenediamine and sebacoyl chloride. alpha-Chymotrypsin is enclosed into the capsule together with polyethyleneimine, capable of joining the walls of microcapsules and making the membrane more stable. The optimal concentrations of polyenthyleneimine and alpha-chymotrypsin are 5% and 1% correspondingly. The highest yield of microencapsulated enzyme was obtained for completely acetylated delta-chymotrypsin. The kinetic properties of microencapsulated alpha-chymotrypsin change very slightly as compared to those of the native one.
...
PMID:[Extraction and properties of microcapsulated alpha-chymotrypsin]. 97 81


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

---