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:1.4.3.13 (lysyl oxidase)
1,248 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The collagens are the major structural glycoproteins of connective tissues. A unique primary structure and a multiplicity of post-translational modification reactions are required for normal fibrillogenesis. The post-translational modifications include hydroxylation of prolyl and lysyl residues, glycosylation, folding of the molecule into triple-helical conformation, proteolytic conversion of precursor procollagen to collagen, and oxidative deamination of certain lysyl and hydroxylysyl residues. Any defect in the normal mechanisms responsible for the synthesis and secretion of collagen molecules or the deposition of these molecules into extracellular fibers could result in abnormal fibrillogenesis; such defects could result in a connective tissue disease. Recently, defects in the regulation of the types of collagen synthesized and in the enzymes involved in the post-translational modifications have been found in heritable diseases of connective tissue. Thus far, the primary heritable disorders of collagen metabolism in man include lysyl hydroxylase deficiency in Ehlers-Danlos syndrome type VI, p-collagen peptidase deficency in Ehlers-Danlos syndrome type VII, decreased synthesis of type III collagen in Ehlers-Danlos syndrome type IV, lysyl oxidase deficency in S-linked cutis laxa and Ehlers-Danlos syndrome type V, and decreased synthesis of type I collagen in osteogenesis imperfecta.
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PMID:Defects in the biochemistry of collagen in diseases of connective tissue. 0 48

Raising day-old chicks on diets lacking copper severely depressed the activity of lysyl oxidase, a copper metalloenzyme in connective tissue. Administration of CuSO4 either through the diet or through intraperitoneal injections restored the lysyl oxidase activity in aortic tissue. Two hours after the chicks received CuSO4 (1 mg/kg) the activity of lysyl oxidase rose rapidly to attain, within 4-6 hr, a new steady-state level which was five to 20 times higher than the basal (saline-injected) activity. Twenty hours after copper administration, activity was still higher, in some experiments double that achieved at 6 hr. Very low amounts of cycloheximide injected intraperitoneally 45 min before and 3 hr after copper suppressed the activation response by two-thirds. Cycloheximide given 2 or 4 hr after the copper was only one-half as effective. Actinomycin D caused only a 10-15% inhibition of the copper-induced activation. The data suggest that copper is a key regulator of lysyl oxidase activity in aorta and may in fact be a major determinant of the steady-state levels of the enzyme in that tissue.
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PMID:Copper-induced activation of aortic lysyl oxidase in vivo. 0 53

Direct evidence showing that a soluble form of elastin is the precursor of cross-linked elastin was obtained from pulse-chase experiments using chick embryo aortas and by demonstrating the conversion of soluble elastin into cross-linked elastin in a cell-free system. Acetic acid extracts of embryonic chick aorta pulse-labeled with [14C]lysine contain two radioactive proteins of molecular weights 74,000 and 138,000 which have been identified previously as soluble elastin and the pro-alpha chain of collagen, respectively. In pulse-chase experiments, the radioactivity incorporated in the soluble elastin during the pulse with [14C]lysine disappeared during a 24-hour chase with [12C]lysine and 89% of that which disappeared was accounted for in the desmosines of alkali-insoluble elastin. The disappearance of the radioactivity from the soluble fraction and its appearance in the desmosines of elastin were inhibited by beta-aminopropionitrile, a specific inhibitor of the cross-linking enzyme lysyl oxidase. In addition in vitro experiments, it was shown that the radioactivity in the desmosines of elastin can arise from that present in an acid-soluble precursor protein. This precursor protein is soluble elastin, as demonstrated by the formation of desmosines when a homogeneous preparation of soluble elastin was incubated with purified lysyl oxidase.
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PMID:Demonstration of a precursor-product relationship between soluble and cross-linked elastin, and the biosynthesis of the desmosines in vitro. 0 2

Activity of lysyl oxidase, an enzyme responsible for production of aldehydic precursors for lysine-derived collagen crosslinks, was measured in tibial metaphyses from chicks receiving different dietary levels of vitamin D and Ca for 2 weeks after hatching. Enzyme activities were increased twofold in D-deficient chicks compared to activities from chicks receiving control levels of vitamin D. Addition of Ca to the D-deficient diet had no effect on lysyl oxidase activity. It is suggested that vitamin D may play a role in the age-related decrease in lysyl oxidase activity that normally occurs in chick bone.
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PMID:Effects of dietary vitamin D and calcium on lysyl oxidase activity in chick bone metaphyses. 0 97

Lysyl oxidase the enzyme which oxidately deaminates lysine residues in collagen and elastin, was purified from embryonic chick cartialge by employing an affinity column of lathyritic rat skin collagen coupled to Sepharose, followed by separation on DEAE-cellulose. An enzyme preparation was obtained which was pure as shown by polyacrylamide gel electrophoresis. The specific activity was 1800-fold higher than that of the original extract. The pure enzyme utilized both collagen and elastin substrate. Furthermore, the ratios of enzyme activity with elastin substrate versus that with collagen substrate were the same at all stages of purity. Only one protein band was found after polyacrylamide gel electrophoresis of the pure lysyl oxidase in sodium dodecyl sulfate and mercaptoethanol. The molecular weight was estimated to be 28000. It was found that the enzyme contained a large number of cysteine and tyrosine residues. Evidence was obtained for molecular heterogeneity of lysyl oxidase. The enzyme eluted from DEAE-cellulsoe in at least four distinct regions. When the peaks were rechromatographed separately, they eluted at salt concentrations similar to those of the original chromatogram. However, the substrate specificity and the electrophoretic mobility on polyacrylamide gel were the same for all enzyme fractions.
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PMID:Properties of highly purified lysyl oxidase from embryonic chick cartilage. 0 18

Aldehyde-deficient non-crosslinked collagen obtained from lathyritic rats and collagen from penicillamine-treated rats, which is not deficient in aldehydes but the crosslinking of which is also inhibited, were implanted into the peritoneal cavity of hypophysectomized rats using the diffusion chamber technique. The enzyme lysyl oxidase which catalyses the aldehyde formation in certain lysyl residues of collagen and elastin was extracted from the skin of hypophysectomized rats. The activity of the enzyme was determined following its incubation with an L-[4,5-3H] lysine-labeled elastin substrate prepared from aortas of 17-day-old chick embryos. The result showed that the aldehyde deficient collagen did not crosslink while in the hypophysectomized animal indicating the lack of active lysyl oxidase in the rats. The enzyme activity in the skin of hypophysectomized animals was markedly reduced as compared with the controls indicating directly the dependance of lysyl oxidase activity on pituitary gland hormones.
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PMID:Lysyl oxidase: a pituitary hormone-dependent enzyme. 0 16

Lysyl oxidase activity of human normal skins derived from the frontal thighs of 33 subjects showed large variations and the mean value was 11 455 +/- 7 172 (S.D.) cpm/g of wet weight tissue. The age of lesion affected the lysyl oxidase activity in postburn scars. Granulation tissues showed a fairly low activity; however, the activity increased sharply within 2--3 months, and reached a significantly higher value than that of normal skin. The high level of activity continued for up to 2--3 years, then gradually decreased to normal range after 5 years or so. Lysyl oxidase activity was detected only after 4 M urea treatment of tissues. Benzylamine oxidase activity also showed large variations in both normal skins and postburn scars, with mean values of: 0.128 +/- 0.077 (S.D.) and 0.145 +/- 0.090 (S.D.) mmol/g of wet weight/h, respectively. No correlation was observed between lysyl oxidase and benzylamine oxidase activities. The granulation tissues showed significantly high values of benzylamine oxidase activity in contrast to the low values of lysyl oxidase activity.
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PMID:Lysyl oxidase activity in human normal skins and postburn scars. 0 13

Lysyl oxidase is a specific amine oxidase that catalyzes the formation of aldehyde cross-link intermediates in collagen and elastin. In this study, lysyl oxidase from embryonic chick cartilage was purified to constant specific activity and a single protein band on sodium dodecyl sulfate acrylamide gel electrophoresis. This band had an apparent molecular weight of 62,000. The eluted protein cross-reacted with inhibiting antisera developed against highly purified lysyl oxidase. The highly purified enzyme was active with both insoluble elastin and embryonic chick skin or bone collagen precipitated as reconstituted, native fibrils. There was low activity with nonhydroxylated collagen, collagen monomers, or native fibrils isolated from lathyritic calvaria. The maximum number of aldehyde intermediates formed per molecule of collagen that became insoluble was two. These results indicate that lysyl oxidase has maximum activity on ordered aggregates of collagen molecules that may be overlapping associations of only a few collagen molecules across. Formation of aldehyde intermediates and cross-links during fibril formation may facilitate the biosynthesis of stable collagen fibrils and contribute to increased fibril tensile strength in vivo.
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PMID:Collagen cross-linking. Purification and substrate specificity of lysyl oxidase. 0 1

In this paper, the synthesis of collagen cross-links in vitro was investigated in a defined system consisting of highly purified chick cartilage lysyl oxidase and chick bone collagen fibrils. Cross-link synthesis in vitro was quite similar to the biosynthesis of collagen cross-links in vivo. Enzyme-dependent synthesis of cross-link intermediates and cross-linked collagen derived from lathyritic collagen occurred. The concentration of the two principal reducible cross-links, N6:6'-dehydro-5,5'-dihydroxylysinonorleucine and N6:6'-dehydro-5-hydroxylysinonorleucine, increased to a peak value of approximately two cross-links per molecule and then decreased. Synthesis of histidinohydroxymerodesmosine and a second polyfunctional cross-link of unknown structure began after synthesis of bifunctional cross-links was largely completed and proceeded linearly afterwards. Inhibition of lysyl oxidase after the bulk of bifunctional cross-link synthesis had occurred did not alter the rate of decrease in reducible cross-link concentration but did inhibit further histidinohydroxymerodesmosine synthesis. These results indicate that lysyl oxidase and collagen fibrils are the only macromolecules required for cross-link biosynthesis in vivo. It is likely that the decrease in reducible cross-links observed during fibril maturation results from spontaneous reactions within the collagen fibril rather than additional enzymatic reactions.
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PMID:Collagen cross-linking. Synthesis of collagen cross-links in vitro with highly purified lysyl oxidase. 0 2

A total of 160 1-2 day old chickens were fed a 2% cholesterol diet for a period of 8 to 42 days and compared with an equal number of controls. Aortas were analyzed for various indexes of reactivity of connective tissue, cholesterol content and scanning electron microscopy (SEM) characteristics of the endothelial lining. Cholesterol feeding for a period up to 6 weeks resulted in doubling the level of serum cholesterol. It was, however, without effect on the activity of prolyl hydroxylase, lysyl oxidase, collagenase and collagen content in the aortic wall. As early as 3 weeks of feeding significant changes occurred in total and esterified cholesterol content. At the same time endothelial cells were characteristically contracted with several long cytoplasmic elongations and protrusions. A significant decrease of activity of the above enzymes was found in aortic tissue with increased age of the chicken. Collagen content in aortas increased with age of chickens. It is concluded that cholesterol as an atherogenic agent induces marked changes in endothelial cells and lipids of chicken aorta at earlier periods, prior to the activation of connective tissue.
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PMID:Early changes in the arterial wall of chickens fed a cholesterol diet. 0 48


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