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

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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)

Analysis of methods of the proteinase substrate specificity determination revealed that Michaelis constants found from the rates of hydrolysis of small synthetic substrates cannot be a good measure of selectivity, especially for proteinases of broad specificity used for hydrolysis of substrates of high molecular mass with multiple cleavage sites. Mass-spectrometric studies (ERIAD) of the hydrolysis of the insulin B chain with trypsin, chymotrypsin, and proteinase I showed that monitoring of the reaction mixtures by means of this technique gives more reliable information on the selectivity of proteinase towards high-molecular substrates.
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PMID:[Mass-spectrometric determination of specificity of proteinases]. 305 18

Evaluation of devices, drugs, and drug delivery systems have been investigated by both in vitro and in vivo procedures. Ceramic drug delivery systems can be used to evaluate chemicals and biologicals by both in vitro and in vivo procedures. The system can also reduce handling of the animals and facilitate long-term evaluations before conducting clinical trials. To date, ceramic systems have been used to deliver aldosterone, androstanedione, beta-lactoglobulin, bovine serum albumin, chymotrypsin, danazol, difluoromeythylornithine, dihydrotestosterone, estradiol, gamma globulin, gonadotrophic releasing hormone, gossypol, growth hormone, insulin, methylene blue, pepsin, progesterone, and testosterone. The data obtained suggest that ceramic delivery systems can be used in the near future to treat diseases requiring long-term chronic drug therapy as well as disorders caused by deficiency of certain hormones.
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PMID:Ceramic systems for long-term delivery of chemicals and biologicals. 323 59

The effects of micelles of nonionic, zwitterionic, anionic and cationic surfactants and lipids on the conformation of glucagon and insulin have been investigated by circular dichroism and intrinsic protein fluorescence. The influence of these amphipathic compounds on the hydrolysis, monitored by HPLC, of glucagon and insulin by trypsin and chymotrypsin has also been studied. The alpha-helix content of glucagon was increased to a similar extent by all the micelles, irrespective of their charge and of whether they were synthetic surfactants or phospholipids. The amphipathic compounds always induced a blue-shift in the wavelength of maximum emission of fluorescence of glucagon of about 9 nm, whereas the fluorescence intensity was increased in some cases and decreased in others. The circular dichroism of insulin was also modified in some cases. Some amphipathic compounds protected glucagon against proteolysis by trypsin and chymotrypsin very markedly, whereas others did not protect at all or only slightly protected the hormone. Two hypotheses have been formulated to explain the different results. Hydrolysis of insulin was generally not influenced by surfactants and lipids.
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PMID:Conformation and proteolysis of glucagon and insulin in surfactant and lipid solutions. 328 14

1. The results of this study indicates that the binding of insulin to brain plasma membranes activates a membrane protease which, by a trypsin like mechanism, produces a soluble factor that modulates the PDH behaviour when added to brain mitochondria. 2. The supernatant from brain plasma membranes incubated with 0.5 mg/ml trypsin added to mitochondria increases PDH activity levels and cancels PDH inhibition by NaF, as has already been seen when the plasma membranes are incubated with 25 microU/ml insulin. No such effects are obtained when the incubation is run out with 0.5 mg/ml chymotrypsin. 3. The supernatants from insulin or trypsin treated plasma membranes retain their activating properties on mitochondrial PDH also after dansylation; from these preparations a dansylated active on PDH material was separated by monodimensional chromatography on HPTLC silica Gel plates, using chloroform/1-butanol (93:7 v/v) as a solvent. 4. Insulin incubation of plasma membranes pretreated with protease inhibitors (leupeptin, phenylmethylsulfonylfluoride) or with exogenous trypsin, but not chymotrypsin substrates (esters of arginine and tyrosine) yields an inactive supernatant on PDH. 5. Insulin treated plasma membrane supernatants lose all stimulating properties on PDH after incubation for 1 hr with 2 mg/ml trypsin or chymotrypsin.
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PMID:Evidence of an insulin generated pyruvate dehydrogenase stimulating factor in rat brain plasma membranes. 331 49

Trypsin and alpha-chymotrypsin effects on masked insulin receptors were studied. Phospholipase C treatment, incubation in a high ionic strength buffer or solubilization were used as alternative procedures for the unmasking of insulin receptors. These three methods expose receptor structures which are inaccessible to insulin in the current experimental conditions of binding assays without any significant change in binding affinity. Both exposed and masked receptors proved to be equally sensitive to trypsin and alpha-chymotrypsin degradation. At 25 degrees C, about 5 micrograms trypsin/ml for 50 min or 80 micrograms alpha-chymotrypsin/ml for 200 min were necessary in each case to cause a 50% inhibition of the binding of 125I-iodo insulin to microsomes. The results suggest that masked receptors are only nonfunctional to bind insulin but they are not located in compartments inaccessible to molecules present in the medium.
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PMID:Effect of proteolytic enzymes on masked insulin receptors in rat submaxillary gland microsomes. 337 53

The present investigation provides follow-up data (up to 36 months) of exocrine and endocrine pancreatic function, inflammatory activity, pain, and body weight in 23 chronic pancreatitis patients submitted to Whipple's procedure plus intraoperative Ethibloc occlusion of the remaining pancreatic duct system between January 1983 and February 1984. Clinically, Whipple's procedure plus intraoperative pancreatic duct occlusion resulted in almost complete and continuous cessation of pain as well as significant (p less than 0.05) increase in body weight. With regard to exocrine pancreatic function (Secretin-Pancreozymin test, plasma amino acid consumption test, Pankreolauryl test, fecal chymotrypsin determination), intraoperative pancreatic duct occlusion was shown to induce high-grade insufficiency and thus exocrine parenchymal atrophy in all patients. Simultaneously, the inflammatory process (represented by serum levels of trypsin, lipase, and pancreatic isoamylase) was terminated in all 23 patients. Endocrine pancreatic function, evaluated by serum levels of insulin and C-peptide measured under fasting conditions and subsequent maximal combined beta-cell stimulation as well as corresponding integrated hormone releases, was reduced by partial pancreas resection by about 50%, while there was no further impairment during the 36-month follow-up period in consequence of additional intraoperative pancreatic duct occlusion. Altogether, Whipple's procedure plus intraoperative Ethibloc occlusion of the residual pancreatic duct system seems suitable for termination of the inflammatory process and thus preservation of residual endocrine pancreatic function in chronic pancreatitis.
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PMID:Whipple's procedure plus intraoperative pancreatic duct occlusion for severe chronic pancreatitis: clinical, exocrine, and endocrine consequences during a 3-year follow-up. 343 10

Skeletal growth factor (SGF) activity was extracted from human bone matrix by demineralization and purified under dissociative conditions using hydroxyapatite, HPLC gel-filtration and HPLC reverse-phase chromatography. Human SGF thus purified was characterized chemically and biologically. Purified human SGF stimulated chick embryo bone cell proliferation at picomolar concentrations (half maximum at 2-3 ng/ml) and had little or no activity on other cell types tested (mouse 3T3 and normal rat kidney fibroblasts, embryonic chick intestinal and human placental cells). Human SGF did not displace 125I-labeled epidermal growth factor binding to normal rat kidney cells and did not stimulate normal rat kidney cell colony formation in soft agar. Human SGF activity was sensitive to trypsin, chymotrypsin, papain, dithiothreitol and performic acid but was resistant to heat (upto 70 degrees C), pH (3-10), cyanogen bromide, alkaline phosphatase and neuraminidase and did not bind jack bean concanavalin A or kidney bean lectin. From our chemical and biological studies it appears that human SGF is different from other known polypeptide growth factors: epidermal growth factor, fibroblast growth factor, insulin, insulin-like growth factor-I, platelet-derived growth factor and transforming growth factor.
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PMID:Chemical and biological characterization of low-molecular-weight human skeletal growth factor. 349 Feb 78

Human erythrocyte lysate was fractionated on various gel filtration media and immunoreactive insulin, insulinase and the influence of individual fractions of the insulin-degrading activity were determined. The hemolysate was shown to contain a complex of substances including an insulin-like substance, insulinase, protease inhibitor and insulinase activator. The insulin-like substance eluted from a Sephadex G-50 column in the same manner as native insulin, and its concentration exceeded the plasma level. Insulinase (Mr 100,000) degraded insulin to the trichloroacetic acid soluble fragments but did not degrade protein or glycoprotein hormones from human pituitaries. Insulinase was inhibited by low temperature, aprotinin and by a newly discovered protease inhibitor from erythrocytes which also inhibits serine proteases--trypsin and chymotrypsin. Another newly discovered substance eluted from a Sephadex G-100 column in the region of low molecular weight substances and showed an insulinase activating activity. The elution patterns of the protease inhibitor and insulinase activator suggest the possibility of the presence of more than one inhibiting and activating factor. The experimental results suggest that the insulin-degrading complex plays a role of a regulator of plasma insulin level. The nonpancreatic origin of the insulin-like substance is also possible.
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PMID:[Insulin-like substance and insulin-degrading complex in hemolysates of human erythrocytes]. 351 29

A galactose binding lectin was isolated from the seeds of the bitter gourd Momordica charantia by delipidation with petroleum ether, extraction with phosphate buffered saline, ammonium sulfate precipitation and affinity chromatography on lactogel. The lectin had a molecular weight of 124,000 and approximately 5% carbohydrate content. The molecular weights of the individual subunits were 37,000, 35,000 and 33,000. The lectin exhibited potent hemagglutinating activity. In addition, it demonstrated antilipolytic and lipogenic activities in isolated rat adipocytes although it did not possess intrinsic lipolytic activity. The antilipolytic activity was susceptible to destruction by heat, trypsin, chymotrypsin, glutathione and galactose, indicating that the integrity of the protein moiety, the disulfide linkages, and galactose, which is the sugar specifically bound by the lectin, all play an important role in interaction with the adipocyte leading to an expression of this insulin-like activity.
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PMID:Isolation and characterization of a galactose binding lectin with insulinomimetic activities. From the seeds of the bitter gourd Momordica charantia (Family Cucurbitaceae). 353 14

A factor able to stimulate pyruvate dehydrogenase when added to purified mitochondria was prepared from the supernatant of brain plasma membranes incubated with physiological concentrations of insulin (25 microU/ml). The factor completely reactivated pyruvate dehydrogenase previously inhibited with ATP and was active on pyruvate dehydrogenase from brain and liver mitochondria and from peripheral lymphocytes. The insulin-dependent stimulator of pyruvate dehydrogenase was heat and acid stable, was not absorbed on charcoal and displayed an isoelectric point of 5.5. The insulin mediator was purified by gel filtration, DEAE-cellulose and sulfonated polystyrene chromatography and, after dansylation, by high performance liquid chromatography. The purified mediator displayed a molecular weight of about 2800 and appeared as a peptide rich in glycine and serine and void of proline and sulfur containing aminoacids. It retained its stimulatory action on pyruvate dehydrogenase after dansylation and was completely inactivated by trypsin and chymotrypsin. Full reactivation of ATP-inhibited pyruvate dehydrogenase was attained when mitochondria were incubated with a mediator concentration of about 0.5 microM.
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PMID:Characterization of a pyruvate dehydrogenase modulator purified from insulin-treated rat brain plasma membranes. 353 96


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