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At least 253 records · Page 14Linked to original sources
PubMed1989

Increased resistance of the collagen in avian dystrophic muscle to collagenolytic attack: evidence for increased crosslinking.

Fibrous collagen from normal (line 412) and dystrophic (line 413) chicken pectoral muscles was examined for susceptibility to bacterial collagenase by a pH-stat titration method to assess the kinetics of peptide bond hydrolysis. These experiments showed that there was a profound difference in the kinetics of hydrolysis using fibrous collagen purified from normal and dystrophic muscle. Although normal collagen was readily hydrolyzed by the collagenase, dystrophic collagen was not hydrolyzed in the presence of 200 microM Ca and was hydrolyzed slowly in the presence of 5 mM Ca. At this high Ca concentration, the Km for collagenase was six times higher in dystrophic collagen than in normal, whereas the maximum reaction rate (Vmax) remained the same. After CNBr digestion, peptides from both sources were readily hydrolyzed by collagenase in the presence of 200 microM Ca, and there was no noticeable difference in the reaction kinetics. The above results were not modified whether the chicken was sacrificed on day 4 or day 98 post-hatching, and the insusceptibility to collagenase preceded the clinical manifestations of dystrophy. The structure of both fibrous and CNBr-treated collagen from normal and dystrophic muscle was compared. One and two-dimensional gel electrophoreses showed identical peptide maps. Gel filtration of CNBr peptides showed in the excluded volume the presence of twice as much high-molecular-weight (presumably crosslinked) peptides from dystrophic collagen compared with normal. We conclude that the intermolecular crosslinks are more extensively formed in dystrophic collagen and that this increased crosslinking results in the increased resistance of the dystrophic collagen to collagenase.

Animals↗
PubMed1978

Subunit structure of Achromobacter collagenase.

The highly active form of collagenase (EC 3.4.24.3) from Achromobacter iophagus (specific activity 2 microkat/mg) has a molecular weight of 70,000 and the sedimentation coefficient s20,2 = 4.4 S. It is composed of two subunits of molecular weight 35,000 and s20,w of 2.9 S. The dissociation of the dimer under different conditions resulted in the complete and irreversible loss of enzymic activity. A unique N-terminal sequence Thr-Ala-Ala-Asp-Leu-Glu-Ala-Leu-Val- indicates that the two subunits are identical, at least in the N-terminal part of the polypeptide chain. Reduction and pyridylethylation of the subunit change neither molecular weight nor amino acid composition: therefore each subunit of molecular weight 35,000 consists of a single polypeptide chain. Another active and homogeneous form of Achromobacter collagenase (specific activity 1.64 microkat/mg) gives a value for the apparent molecular weight of 80,000 on sodium dodecyl sulphate-polyacrylamide electrophoresis. It is also a dimer in which each of the two subunits of molecular weight 35,000 binds non-covalently a peptide of molecular weight 5000. The dissociation of this form of collagenase is also accompanied by irreversible loss of enzymic activity. The amino acid composition of the subunits which were isolated from both 70,000 and 80,000 collagenases is the same. The role of dimer-monometer equilibrium in the biological function of collagenase is discussed.

Alcaligenes↗
PubMed1978

Cleavage of native type III collagen in the collagenase susceptible region by thermolysin.

Viscometric assays were used to demonstrate the activity of thermolysin (EC 3.4.24.4) on native type III collagen in solution. Analysis of the reaction products by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and electron microscopic visualisation of segment long spacing aggregates demonstrated localised cleavage of the collagen in the collagenase susceptible region.

Collagen↗
PubMed1976

Production of collagenase by mouse peritoneal macrophages in vitro. Characterization of sites of cleavage of tropocollagen.

Macrophages from mineral oil-stimulated mice produce collagenase at a constant rate over several days in culture. Phagocytosis of latex does not increase production of enzyme. Gel electrophoretic and electron microscopic analyses indicate that the specificity of the macrophage enzyme is similar to that of other previously characterized mammalian collagenases.

Animals↗
PubMed1977

Chemical composition and swelling of normal and osteoarthrotic femoral head cartilage. II. Swelling.

Studies of the equilibrium, partition, and diffusion of tritiated water were carried out on normal and osteoarthrotic cartilage as well as on cartilage from which proteoglycans had been extracted chemically. All the water was found to be freely exchangeable in both normal and degenerate specimens. The diffusiviity of the water was equal to about 40% of the value in free solution, with an activation energy equal to that in free solution. It was concluded that the swelling of degenerate tissue is not due to any changes in the state of the water, but to a failure of the damaged collagen network to oppose the swelling pressure of the proteoglycans. Swelling similar to that observed in fibrillated cartilage was also found in initially normal specimens treated with collagenase.

Cartilage, Articular↗
PubMed1990

[Effect of PTH and periodic tension on osteoblast-like cells for collagenase synthesis].

The purpose of the present study was to determine whether cyclically applied tension stimulates osteoblast-like cells to produce collagenase as well as parathyroid hormone (PTH) does. Experimental evidences suggest that osteoblast growth can be altered by various extrinsic control factors, including continuous and intermittent mechanical forces. In the present study, morphological change and collagenase synthesis were observed for both cultures that were added PTH and under the periodic tension condition applied on osteoblast-like cells and their parallel controls. periodic tension was used because it was thought to more closely mimic the in vivo functional situation. An initial seeding density of 50,000 cells/well was used for both the PTH stimulated and mechanically stimulated cells and their controls. For the mechanically stimulated cultures, the cells were subjected to the following tension/relaxation combination; 3 cycles/minute at 17% elongation of tensional force. The cells were fixed at 24, 72, and 120 hours after the start of experiments and collagenase was stained immunohistochemically. The following results were obtained: 1. PTH stimulated collagenase production from the first through the fifth day; 2. Periodic tension changed cell morphology from round to stellate; and 3. Periodic tension increased collagenase production from the first through the fifth day.

Animals↗
PubMed1979

Macrophage inhibition of collagen-induced platelet aggregation.

Collagen was incubated with cells or media fractions of mouse peritoneal macrophage cultures, and its aggregating effect on human platelets was tested. Incubation with lysates of cultured cells completely abolished the normal collagen-induced platelet aggregation, while incubation with media fractions only caused partial inhibition. The latter inhibition was more pronounced after macrophage phagocytosis of latex particles, while endocytosis of endotoxin had no effect. Corresponding macrophage cultures were also tested for specific collagenase activity, using 14C-glycine labelled collagen as substrate. Collagenase activity was found in the culture media fractions only, and the enzyme activity could be enhanced by endocytosis of latex as well as endotoxin. It appears that the effect of macrophage lysates and media on collagen-platelet interaction cannot be ascribed only to secretion of collagenase from macrophages.

Animals↗
PubMed1988

[Collagenases and cancers].

We analyze here recent data from literature concerning the role of collagenases in cancer. The alteration of basement membrane (BM) and extracellular matrix components, in particular collagens, has been widely reported during tumor invasion. The collagenases degrade interstitial collagens (types I and III) and BM collagens (type IV). So, they break natural barriers and allow tumor cells to spread in surrounding tissues and metastasize. Classical collagenases are not able to degrade type IV collagen (the main component of BM) which, however, often appears to be very altered around tumor cells. Therefore, the existence of a specific type IV collagenase is necessary to explain this phenomenon. Most studies performed with the object of proving the role of collagenases in tumor invasion and metastasis have shown the presence of a type I collagenase, but type IV collagenase has been more difficult to evidence.

Animals↗
PubMed1987

[Effect of collagenase on neuromuscular transmission in the frog].

Modification of synaptic function was estimated through the action of 0.1% solution of collagenase on neuromuscular junction in frog. Electrophysiological experiments revealed a decrease of the e.p.p. quantum content on single nerve stimulation with collagenase. The latter or the product of its splitting modify the action zones of mediator secretion. The demyelination action of collagenase on nerve is discussed.

Animals↗