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

The cytochrome d complex is a two-subunit, membrane-bound terminal oxidase in the aerobic respiratory chain of Escherichia coli. The enzyme catalyzes the two-electron oxidation of ubiquinol and the four-electron reduction of oxygen to water. Previous work demonstrated that the site for ubiquinol oxidation was selectively inactivated by limited proteolysis by trypsin, which cleaves at a locus within subunit I. This work is extended to show that a similar phenomenon is observed with limited chymotrypsin proteolysis of the complex. The cleavage patterns are similar whether one uses the purified oxidase in nondenaturing detergent or reconstituted in proteoliposomes or uses spheroplasts of E. coli as the substrate for the proteolysis. Hence, the protease-sensitive locus is periplasmic in the cell. Fragments resulting from proteolysis were characterized by N-terminal sequencing and by immunoblotting with the use of a monoclonal antibody of known epitope within subunit I. The data indicate that inactivation of the ubiquinol oxidase activity results from cleavage at specific residues with a hydrophilic region previously defined as the Q loop. This domain has been already implicated in ubiquinol oxidation by the use of inhibitory monoclonal antibodies. Electrochemical and HPLC analysis of the protease-cleaved oxidase suggests no global changes in either the quaternary or tertiary structure of the enzyme. It is likely that the Q loop is directly involved in forming a portion of the ubiquinol binding site near the periplasmic surface of the membrane.
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PMID:Proteolysis of the cytochrome d complex with trypsin and chymotrypsin localizes a quinol oxidase domain. 170 10

The alpha-chymotrypsin-catalyzed hydrolysis of succinyl-L-alanyl-L-alanyl- L-prolyl-L-phenylalanyl p-nitroanilide has been studied in reverse micelles of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in isooctane. It has been found that alpha-chymotrypsin is strongly inhibited competitively by the acidic peptide product which is formed during the course of the reaction. It has also been shown that the application of the integrated form of the Michaelis-Menten equation can be useful to detect possible inhibition effects and abnormal kinetic behavior of enzymes in reverse micelles. Furthermore, it has been shown that the turnover number (kcat) at low water content is lower than in water and increases as the water content in the system is lower than in water and increases as the water content in the system (wo = [H2O]/[AOT]) increases, kcat reaching the value in water at high wo. If however, initial velocity data, as obtained under conditions where the enzyme is not saturated with substrate, are plotted against wo, the curves are bell-shaped, with a maximum around wo = 15.
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PMID:Product inhibition of alpha-chymotrypsin in reverse micelles. 171 3

We have investigated the transmembrane topology of the bovine heart mitochondrial porin by means of proteases and antibodies raised against the amino-terminal region of the protein. The antisera against the human N-terminus reacted with porin in Western blots of NaDodSO4-solubilized bovine heart mitochondria and with the membrane-bound porin in enzyme-linked immunosorbent assay (ELISA). The immunoreaction with mitochondria coated on microtiter wells showed that the amino-terminal region of the protein is not embedded in the lipid bilayer but is exposed to the cytosol. Back-titration of unreacted anti-N-terminal antibodies after their incubation with intact mitochondria demonstrated that the porin N-terminus is also exposed in "noncoated" mitochondria. No difference in antisera reactivity was observed between intact and broken mitochondria. Intact and broken mitochondria were subjected to proteolysis by specific proteases. The membrane-bound bovine heart porin was strongly resistant to proteolysis, but a few specific cleavage sites were observed. Staphylococcus aureus V8 protease gave a large 24K N-terminal peptide, trypsin produced a 12K N-terminal and an 18K C-terminal peptide, and chymotrypsin gave two peptides of Mr 19.5K and 12.5K, which were both recognized by the antiserum against the human N-terminus. Carboxypeptidase A was ineffective in cleaving the membrane-bound porin in both intact and broken mitochondria. Thus, the carboxy-terminal part of the protein is probably not exposed to the water phase. The cleavage patterns of membrane-bound porin, obtained with S. aureus V8 protease, trypsin, and chymotrypsin, showed no difference between intact and broken mitochondria, thus indicating that all porin molecules have the same orientation in the membrane. The computer analysis of the sequence of human B-lymphocyte porin suggested that 16 beta-strands can span the phospholipid bilayer. This result, together with the overall information presented, allowed us to draw a possible scheme of the transmembrane arrangement of mammalian mitochondrial porin.
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PMID:Peptide-specific antibodies and proteases as probes of the transmembrane topology of the bovine heart mitochondrial porin. 171 14

Pancreatic juice was continuously diverted from the Wirsungial duct by nasopancreatic drainage of the remnant of the gland after pylorus preserving partial pancreato-duodenectomy in 14 patients. On the 7th postoperative day with stabilized pancreatic secretion the juice was collected in 10 min fractions, while interdigestive secretory phases of the parenchyma were established by volume changes. At the beginning of a phase 100 ml slightly hyperosmolar (400 mosmol/L) oligopeptide diet with 90 kcal was given as a bolus injection for 7 patients or 60 min infusion into the second jejunal loop by fine needle catheter jejunostomy for 7 patients also. Pancreatic water, bicarbonate, protein, chymotrypsin, amylase levels peak, and integrated secretory responses were measured. It was observed, that infusion of the diet did not disturb cycling interdigestive phases and did not increase peak and integrated outputs. Bolus administration interrupted interdigestive phases and stimulated pancreatic water, bicarbonate, protein, chymotrypsin and amylase outputs nonparallelly. On the basis of their data authors concluded, that pancreatic secretion seems to be well preserved without duodenalregulatory mechanisms; and continuous jejunal infusion feeding seems to be useful in pancreatic disease and in other postoperative states when pancreas has to be put into rest.
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PMID:[The effect of two different methods of jejunal feeding on pancreatic function]. 175 91

Copolymers of acrylated derivatives of alpha-chymotrypsin and polyethylene glycol (PEG) have been prepared and used as biocatalysts for the synthesis of model peptides in organic solvent containing a low quantity of water. Other peptide couplings have been tried to point out the chemico- and stereoselectivity and examples of segment couplings are given.
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PMID:Enzymatic peptide synthesis in organic solvent mediated by gels of copolymerized acrylic derivatives of alpha-chymotrypsin and polyoxyethylene. 176 73

11 amino acid derivatives were tested as alpha-chymotrypsin substrates in the esterification reaction with methanol in organic media. The reactions were carried out in water-saturated ethyl acetate and in acetonitrile containing 4% water. alpha-Chymotrypsin adsorbed on Celite was used as a catalyst. From initial reaction rate measurements, the Michaelis-Menten parameters Vmax and KM were determined. All the amino acid derivatives tested were esterified, and the highest values of kcat/KM were obtained with the N-acylated aromatic amino acids. Correlations between Michaelis-Menten parameters and physical properties of the substrates such as molar refractivity (MR) and log P were deduced. The results show that the specificity of the alpha-chymotrypsin towards the side chain of the amino acids in organic media is the same as that in aqueous media. However, the specificity towards the N-protecting group is opposite to that in water, so the reaction medium affects the interaction of this part of the molecule with the enzyme to a large extent.
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PMID:Substrate specificity of alpha-chymotrypsin-catalyzed esterification in organic media. 176 79

Pancreatic exocrine secretion was estimated in 180 normal control patients, free of abdominal and pancreatic disease, aged from 16 to 83 years. Duodenal juice was collected in two 15-min fractions after a single intravenous injection of 1 U/kg secretin + 3 U/kg CCK. Volume, maximal concentration and output of bicarbonate, lipase, phospholipase and chymotrypsin were estimated as well as minimal concentration and output of chloride and calcium. Each parameter was plotted against age, either individually or after separation into two age groups. Volume linearly increased up to the 3rd decade, and thereafter linearly decreased. Bicarbonate secretion paralleled fluid secretion and also decreased after the 3rd decade. The changes in chloride and calcium concentrations were different: concentrations linearly increased after the 3rd decade. Calcium concentration linearly increased with age (p less than 0.02) while chloride output was unchanged. The three enzymes that were studied linearly decreased in concentration as well as in output with age from the 3rd decade (p less than 0.02). Protein secretion decreased before water and bicarbonate secretion. One can conclude that pancreatic secretion changes in humans with age. Aging alters pancreatic secretion, through a decrease in flow rate, bicarbonate and enzyme secretion while calcium concentration is enhanced. Although not requiring substitutive therapy in the whole population, individual cases of pancreatic exocrine insufficiency might be explained by aging, without malnutrition.
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PMID:Changes in pancreatic exocrine secretion with age: pancreatic exocrine secretion does decrease in the elderly. 181 45

Peptide synthesis with chymotrypsin in organic solvents was investigated and the apparent partition constants have been measured. We find that the Papp values of the most amino acids and peptide derivatives are drastically changed and the stereo- and regiospecificity in acetonitrile/water mixture is reduced.
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PMID:Chymotrypsin-catalyzed peptide synthesis in an acetonitrile-water-system: studies on the efficiency of nucleophiles. 182 34

The synthesis of the chromogenic substrates for trypsin-like proteinases catalyzed by alpha-chymotrypsin and subtilisin from B. subtilis strain 72 were carried out in the organic media at a low water content using the enzymes adsorbed on different porous materials. The method proposed allows us to vary the structure of the compounds to be synthesized and is a suitable technique for their scaling-up.
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PMID:The synthesis of chromogenic peptide substrates containing p-nitroanilides of arginine and lysine, catalyzed by proteinases adsorbed on support material. 182 48

Copolymerized compounds of acrylated derivatives of alpha-chymotrypsin and polyethylene glycol (P.E.G.) have been prepared and used as biocatalysts for peptide synthesis in organic solvent containing low quantity of water. In order to increase the velocity of the coupling reactions, without loss of enzyme activity, we have used the principle of sonication. Some results and future projects are presented.
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PMID:Sono-enzymatic peptide synthesis in organic solvent. 182 49


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