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:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The lathyrogens, beta-aminopropionitrile and alpha-aminoacetonitrile inhibit both the esterolytic and proteolytic activity of trypsin at a concentration of 100 mM. Lineweaver-Burk plots demonstrate that inhibition is competitive, with alpha-aminoacetonitrile being the more potent inhibitor. The enzyme associated with and capable of digesting tropoelastin is inhibited by both lathyrogens when tested against its natural substrate, tropoelastin. Administration of alpha-aminoacetonitrile-HCl to the diet of young chicks (0.1% w/w) resulted in a 62% increase in the yield of tropoelastin and significant reduction in fatality as compared to beta-aminopropionitrile-fumarate.
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PMID:The anti-proteolytic behavior of lathyrogens. 50

Chick plasma contains inhibitor(s) against trypsin and elastase which also appear to retard the degradation of tropoelastin by arterial tissue extracts. Chick aorta extracts also contain similar inhibitors against elastase and trypsin. Both levels of the plasma inhibitor(s) and inhibitor(s) extracted from thoracic aorta increase during early stages of growth and maturation. There is a three- to four-fold increase in the levels of the inhibitor(s) in chick plasma and aorta between one to four weeks after hatching. Of particular interest are the observations that the presence of the inhibitor(s) retards the conversion of soluble elastin (tropoelastin) to smaller elastin peptides. Subsequently, it is speculated that in addition to other vital roles, such proteinase inhibitors may also act in regulating elastogenesis and elastin fiber formation.
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PMID:Inhibition of elastolysis by proteinase inhibitors from chick plasma and aorta. 63 1

The presence of an enzyme associated with tropoelastin is described. The enzyme has a pH optimum between 7 and 9 and trypsin-like specificity. Upon incubation, tropoelastin (72,000 molecular weight) is cleaved into relatively high molecular weight fragments. In addition to the parent molecule, five discrete polypeptide bands are usually observed on SDS gels with molecular weights of approximately 57,000, 45,000, 36,000, 25,000 and 13-14,000.
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PMID:Proteolysis of tropoelastin. 86 36

Isolation of tropoelastin is complicated by the presence of a neutral protease closely associated with tropoelastin that is capable of sequentially degrading tropoelastin to small peptides. Substrate and inhibitor specificities of this neutral protease associated with purified tropoelastin were examined. The enzyme displayed proteolytic activity against casein, and esterase activity was detected when assayed against N-tosyl-L-arginine methyl ester but not against tert-butyl-oxycarbonyl-L-alanine p-nitrophenyl ester. No appreciable elastinolytic activity was detectable against either insoluble sodium dodecyl sulfate treated elastin or maleylated tropoelastin. The enzyme was not inhibited by the chymotrypsin inhibitor toluenesulfonylphenylalanine chloromethyl ketone. The enzyme was inhibited by phenylmethanesulfonyl fluoride and, to various degrees, by metal chelators. Tosyllysyl chloromethyl ketone, epsilon-aminocaproic acid, and Aprotinin (pancreatic trypsin inhibitor--Kunitz type), all inhibitors of trypsin-like enzymes, were very effective inhibitors, as were soybean trypsin inhibitor and human alpha-1-antitrypsin. The data suggest that the tropoelastin-associated enzyme is a neutral serine protease with trypsin-like specificity.
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PMID:Trypsin-like neutral protease associated with soluble elastin. 90 57

Tropoelastin was isolated from the aortas of chicks rendered lathyritic by treatment with beta-aminopropionitrile. The soluble elastin was judged homogeneous by sodium dodecyl sulfate polyacrylamide gel electrophoresis and possessed an estimated molecular weight of 70000. Automated sequential analysis revealed that the N-terminal region of the chick tropoelastin is very homologous to tropoelastin isolated from copper-deficient piglets. N-terminal analysis of a trypsin digest of chick tropoelastin showed that tyrosine frequently is found adjacent to lysine residues. This positioning of tyrosine residues may be significant in terms of a possible regulatory role in elastin cross-link formation.
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PMID:Isolation of soluble elastin from lathyritic chicks. Comparison to tropoelastin from copper deficient pigs. 119 41

Elastic fibers comprise elastin and other proteins termed as elastin-associated proteins. The nature of association between the elastin and elastin-associated-protein is not known. We have isolated elastic fibers from 5-month-old porcine aorta and lung parenchyma using urea, dithiothreitol and 1% sodium dodecyl sulfate at 55 degrees C. Lysyl-derived crosslinks were stabilized by sodium borohydride reduction. The methionine residues and associated peptides were decreased by CNBr treatment. Limited proteolysis of elastic fibers obtained by this procedure by trypsin (TPCK) and chymotrypsin (TLCK), removed 3% and 11% of the elastic fibers from aorta and lung, respectively. Limited elastase digestion solubilized a further 12 to 14% of the elastic fiber from aorta and lung samples, respectively. The insoluble residue remaining after elastase digestion had amino acid composition similar to alkali extracted elastin and to tropoelastin. The material solubilized by chymotrypsin and trypsin contained lysinonorleucine, whereas desmosine crosslinks were present only in the elastase digests. Aorta and lung elastic fibers differ in their structures as indicated by quantitative differences in limited proteolysis. These results strongly indicate that elastin and elastin-associated proteins interact strongly through lysyl-derived crosslinks.
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PMID:Elastin and elastin-associated-protein of porcine aorta and lung. 217 93

Soluble 125I-labeled tropoelastin bound to confluent cultures of bovine ligamentum nuchae fibroblasts and to fibroblast plasma membrane preparations in a time-dependent, saturable, and reversible manner. Scatchard analysis indicates that there are approximately 2 X 10(6) binding sites/cell with a binding efficiency (Kd) of 8 X 10(-9) M. Binding of tropoelastin to cells and membranes reached equilibrium by 90 min and was reversible with 50% of specifically bound material released by 40 min. Specific binding of tropoelastin to cells pre-treated with dilute trypsin solutions was reduced significantly when compared with controls. Four polypeptides of estimated molecular masses of 67, 61, 55, and 43 kDa were obtained from detergent extracts of plasma membranes by elution affinity chromatography on elastin-Affi-Gel. Our findings establish that elastin-specific binding proteins displaying characteristics of a true receptor are present on the surface of elastin-producing cells.
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PMID:Kinetics of receptor-mediated binding of tropoelastin to ligament fibroblasts. 282 64

The objective of this study was to investigate the elastin repair process in the rat aortic smooth muscle cell culture after proteolytic injury. Although little studied in vivo, elastin repair is thought to occur through a sequential process involving enzymatic removal (debridement) of damaged fibers followed by synthesis of tropoelastin, its subsequent processing, and eventual incorporation into new insoluble elastin. A second repair mechanism of proteolytically damaged elastin in a culture system is reported here. Repair in this system relates directly to restoration of resistance to elastin solubilization by hot alkali. As expected, severe injuries were observed with porcine pancreatic elastase (PPE). Using PPE, only 6% of the elastin, relative to control, was resistant to hot alkali immediately after elastase treatment. 4 wk later, resistance to hot alkali had increased dramatically to a mean of 90%. Repair took longer after injury with 75 micrograms of PPE as compared with 50 micrograms of PPE. The limited elastic fiber proteolysis induced by either human neutrophil elastase or porcine trypsin was repaired in culture within 2 wk. Elastin that had been radiolabeled with [3H]lysine 4-5 wk before injury was converted from a hot NaOH-susceptible to a NaOH-resistant elastin fraction during recovery from PPE injury. At the same time, the frayed elastic fibers that were seen with the electron microscope immediately after PPE treatment were replaced by continuous bands of elastin that resembled those in control cultures. Restoration of NaOH resistance did not require a net increase in total cell layer elastin, suggesting that relatively little new tropoelastin incorporation into the cell layer was required for this type of repair. These results suggested a salvage repair mechanism for proteolytically damaged elastin.
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PMID:Repair of protease-damaged elastin in neonatal rat aortic smooth muscle cell cultures. 314 80

Tropoelastin was isolated from aortae and auricular cartilage obtained from lathyritic piglets. The two tissue-specific tropoelastins were judged homogeneous by sodium dodecyl sulfate polyacrylamide gel electrophoresis and gel filtration on a high-pressure liquid chromatograph. Comparative studies of the tropoelastins were performed. Amino acid analysis revealed that the aortic and cartilage tropoelastins were very similar, if not identical, with the only exception that the cartilage tropoelastin contained more hydroxyproline and less lysine residues, both of which can be attributable to post-translational modifications. Both tropoelastins possess an apparent molecular weight of 70 000 and exhibit similar peptide fragments with limited trypsin cleavage. Antiserum raised to the aortic tropoelastin was used to show immunological identity between the two tissue tropoelastins.
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PMID:Comparison of aortic and ear cartilage tropoelastins isolated from lathyritic pigs. 721 56

Tropoelastin expression in vascular smooth muscle cells during serial cell passages from the primary to the tertiary culture was studied. The level of tropoelastin was found to be greatly reduced as the number of cell passages increased. The translational activity and level of elastin mRNA were essentially unchanged throughout the cell passages. The reduction in tropoelastin expression was not due to the repetitive trypsin treatment nor to the prolyl hydroxylation level of the newly-synthesized elastin. A comparable decline in tropoelastin expression was also found with increasing cell division in the primary cultures plated at different cell densities. A pulse-chase experiment revealed that the newly-synthesized elastin in the tertiary culture degraded more rapidly than that in the primary culture. The culture medium harvested from the tertiary culture exhibited a higher tropoelastin-degrading activity than that from the primary culture in the test-tube. The degrading activity of the tertiary culture was inhibited by the addition of 1 mM ethylenediaminetetraacetic acid or 1 mM phenylmethylsulfonyl fluoride, but not by 1 mM N-ethylmaleimide. These results suggest that the reduction in tropoelastin expression during the cell passages from the primary to the tertiary culture is due to the enhanced tropoelastin-degrading activity of the tertiary culture. The transition to tropoelastin-degrading phenotype during cell passages may explain the biological mechanisms of smooth muscle cell migration from the media to the intima observed in the pathological conditions.
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PMID:Enhanced tropoelastin-degrading activity during cell passages in cultured smooth muscle cells. 772 14


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