Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.4.3.13 (lysyl oxidase)
 1,248 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cultured vascular endothelium secretes the enzyme lysyl oxidase which cross-links both collagen and elastin. The major reducible cross-link synthesized by cultured human umbilical arterial and venous endothelium is dihydroxylysinonorleucine (di-OH-LNL). Treatment of the cultures with the lathyrogen beta-aminopropionitrile (BAPN), which inhibits lysyl oxidase, inhibited synthesis of this cross-link. Cultured porcine aortic endothelium synthesized three major reducible lysine-derived cross-links: dihydroxylysinonorleucine (di-OH-LNL), hydroxylysinonorleucine (OH-LNL) and lysinonorleucine (LNL); BAPN also inhibited synthesis of these three cross-links. Earlier in-vivo observations on BAPN-treated chick embryos had shown a 20% increase in the hydration of cartilage and other tissues; the likeliest explanation was that cross-link disruption permitted the proteoglycans in cartilage to express their hydrophilic nature when freed of their collagenous network. Capillary basement membrane contains laminin, proteoglycan and type IV collagen. Following the finding of oedema in lathyritic cartilage, we would propose that agents which disrupt collagen cross-links in cultured vascular endothelium, damaging capillary basement membrane, be considered as one possible mechanism in the pathogenesis of oedema.
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PMID:Collagen cross-link synthesis in cultured vascular endothelium. 260 12

The levels of two enzymes of collagen biosynthesis namely lysyl oxidase and prolyl hydroxylase were measured in the lungs of rats 3 and 6 weeks after receiving a single intratracheal instillation of silica or sterile saline. Circulating levels of lysyl oxidase were also estimated. Significant increased lung-enzyme activities were observed in the silica-exposed rats at both time intervals. Plasma levels of lysyl oxidase were also found to be raised in the silica-exposed rats. These changes were not, however, accompanied by profound pathological alterations. These results demonstrate that after exposure to silica histologically detectable fibrosis is preceded by significant changes in the activities of enzymes associated with collagen synthesis.
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PMID:Measurements of enzymes of collagen synthesis in rats with experimental silicosis. 285 71

Lysyl oxidase, the enzyme responsible for mediating crosslink formation in collagen and elastin, requires copper for its activity. In this study, lysyl oxidase activity and insoluble elastin content were unchanged in lungs from copper-deficient hamsters compared to controls. The lack of dramatic diminution in lysyl oxidase activity in animals who demonstrate significant structural alterations in the lung suggests that other mechanisms in addition to inhibition of crosslink formation are operative in this model.
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PMID:Lysyl oxidase activity in lungs of copper-deficient hamsters. 285 44

Extracts of bovine ligamentum nuchae have been assayed for lysyl oxidase activity using as substrates soluble elastin and soluble collagen labeled with tritiated lysine. The assays were performed in the presence and absence of sodium oleate. At 0.8 mM, oleate decreased activity with elastin more than 50% and enhanced activity with collagen to approximately 200% that of controls without oleate. The results show that this hydrophobic anion modulates lysyl oxidase specificity in crude extracts and suggests a mechanism for modifying activity in tissues.
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PMID:Modulation of lysyl oxidase substrate specificity by the oleate anion. 285 98

Lysyl oxidase, which plays an important role in collagen deposition in chronic liver diseases, was studied in nonparenchymal cell cultures from fibrotic human livers. Liver biopsy specimens were obtained from control patients without apparent hepatic disease, and from patients with chronic persistent hepatitis, chronic active hepatitis, or liver cirrhosis. Nonparenchymal cells from biopsy specimens were cultured. At the third passage of the culture, lysyl oxidase activity was measured in the culture medium and cell layer. Most of the activity in the culture medium of cirrhotic liver cells was significantly higher than that in the medium of liver cells from controls or from patients with chronic hepatitis, whereas no significant difference in activity was noted between chronic persistent hepatitis and chronic active hepatitis cells. In patients with chronic hepatitis, lysyl oxidase activity in the culture medium from liver cells of alcoholics was significantly higher than that in the medium from liver cells of nonalcoholics. Thus, increased lysyl oxidase activity was found in the medium of nonparenchymal cell cultures from patients with cirrhosis and from alcoholics with chronic hepatitis. This increased activity may be related to fibrotic processes in the liver.
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PMID:Increased lysyl oxidase activity in culture medium of nonparenchymal cells from fibrotic livers. 286 89

The activities of prolyl 4-hydroxylase, galactosylhydroxylysyl glucosyltransferase (GGT) and lysyl oxidase (three enzymes catalysing post-translational modifications of collagen) were measured in the lungs of rats exposed to silica (DQ12). Circulatory levels of GGT were also estimated. Rats were killed after 24 h and at 6, 12 and 24 weeks after a single intratracheal instillation of either 12.5 or 25 mg of silica (DQ12). Control animals received saline. The total activity of the three enzymes in the lungs of the exposed animals was significantly increased at all times (P less than 0.05). The circulatory levels of GGT were also increased though some differences failed to reach significance. Thus increased activities of enzymes of collagen biosynthesis correlated with the development of silicosis and occurred within 24 h of treatment. This suggests that the changes responsible for the eventual development of fibrosis are operative within hours of dust exposure.
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PMID:Collagen biosynthesis enzymes in lung tissue and serum of rats with experimental silicosis. 286 66

Streptozotocin (STZ)-induced diabetes (8 weeks) produced a marked depressor effect in the spontaneously hypertensive rat (SHR), confirming earlier studies, but had no effect on arterial pressure of normotensive controls (WKY). We investigated the phenomenon further by examining the effects of diabetes on the activities of aortic prolyl hydroxylase (PH) and lysyl oxidase (LO), marker enzymes for collagen biosynthesis, and on the reactivity of isolated mesenteric arteries to vasoactive agents. PH and LO activities of nondiabetic SHR were greater than those of the WKY controls. Diabetes markedly reduced PH and LO activities of SHR aortae, but had no significant effect on PH and LO activities of the WKY strain. The effects of diabetes on vascular collagen biosynthetic enzymes of SHR were not associated with reductions in mesenteric arterial responsiveness or sensitivity to norepinephrine, methoxamine, serotonin or KC1. These results suggest that the depressor effect of diabetes in SHR is associated with a reduction in vascular collagen biosynthesis but not a reduction in vascular reactivity.
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PMID:Depressor effect of diabetes in spontaneously hypertensive rat: role of vascular reactivity and prolyl hydroxylase and lysyl oxidase activities. 286 37

The effect of serum from type IIA hyperlipoproteinemic patients on the proliferation and synthesis of collagen and other proteins of human fetal aortic smooth muscle cells (SMC) was studied. The activity of lysyl oxidase secreted into the culture medium was also measured. Type IIA hyperlipoproteinemic sera did not affect the proliferation of human aortic SMC as compared to normolipidemic sera, regardless of incubation time. The findings were similar for 3 different human fetal aortic SMC lines and one fibroblast line from adult human skin. The synthesis of collagen and other proteins was inhibited rather than stimulated in the presence of type IIA hyperlipoproteinemic sera. The activity of lysyl oxidase was not affected by type IIA hyperlipoproteinemic sera. The atherogenicity of hypercholesterolemia cannot be explained either by its direct effect on the proliferation of arterial SMC, as has been suggested by animal cell studies, or by its direct effect on the fibrogenicity of these cells.
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PMID:Serum from type IIA hyperlipoproteinemic patients does not stimulate proliferation of and collagen synthesis in human fetal aortic smooth muscle cells in culture. 286 78

The binding of highly purified bovine aortic lysyl oxidase to native fibrils of type I collagen has been measured by assay of unbound lysyl oxidase activity in the supernatants of enzyme-collagen mixtures after centrifugation. The apparent binding affinity of lysyl oxidase for native fibrils is quite similar to that for fibrils prepared from pepsin- or chymotrypsin-digested type I collagen, demonstrating that the enzyme binds to the triple-helical portion of collagen molecules. The data also indicate that the enzyme binds predominantly to the fibrillar surface. The results suggest that lysyl oxidase initiates crosslink formation at an early stage in collagen fibrillogenesis.
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PMID:Binding of lysyl oxidase to fibrils of type I collagen. 286 30

Lung tissue from groups of chicks raised 23 d on diets deficient in copper had a higher proportion of 0.15 M NaCl-extractable collagen but lower aldehyde-reacting compounds and elastin than controls the same age. Although the lungs from deficient chicks weighed less, the ratio of lung to body weight for the two groups stayed relatively constant throughout the 23-d period. Lysyl oxidase activity in lungs of deficient chicks was strongly suppressed. Feeding the deficient chicks the diet with copper supplements restored lysyl oxidase activity in lung. This showed the close and specific control of lung lysyl oxidase by copper. The impairment in cross-linking through lysyl oxidase failure is implied from these studies. Clearly, copper is needed for the normal development of lung.
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PMID:Biochemical defect in chick lung resulting from copper deficiency. 286 81


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