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

---

Query: EC:3.4.24.3 (collagenase)
18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously shown that arginine vasopressin (AVP) directly inhibits testicular steroidogenesis in vitro. In the present study, binding of neurohypophysial peptides to interstitial cells of the rat testis was studied using [3H]AVP as the ligand. Interstitial cells were obtained from adult rat testis after collagenase dispersion and were incubated with [3H]AVP in the presence or absence of unlabeled AVP. Binding equilibrium was reached by 60 min at 4 C, while incubation at higher temperatures (23 and 37 C) resulted in an apparent decrease in binding. Scatchard plot analysis of equilibrium binding data revealed the existence of one class of high affinity, low capacity binding sites (Kd = 1.0 +/- 0.3 nM; maximal binding = 8.5 fmol/10(6) cells). In addition, the rate constants of association and dissociation were calculated to be 0.024 nM-1 min-1 and 0.009 min-1, respectively. Addition of naturally occurring neurohypophysial hormones as well as their synthetic analogs inhibited [3H]AVP binding to testis cells, resulting in parallel displacement curves. The order of potencies for the native peptides was: AVP = lysine vasopressin = arginine vasotocin (IC50, 5 X 10(-10) M) greater than oxytocin = mesotocin (IC50, 4 X 10(-7) M) greater than isotocin = glumitocin (IC50 greater than 10(-6) M). Furthermore, two potent vasopressor antagonists, d(CH2)5Tyr(Me)AVP ([1-(beta-mercapto-beta, beta-cyclopentamethylenepropionic acid), 2-(O-methyl)tyrosine]AVP) and dPTyr(Me)AVP ([1-deaminopenicillamine-2-(O-methyl)tyrosine]AVP) competed for [3H]AVP binding with a higher affinity (IC50, approximately 10(-11) M) than native AVP. In contrast, a selective antidiuretic agonist, dDAVP (1-deamino-8-D-AVP), only competed weakly for receptor binding, while a specific oxytocic agonist, (Thr4,Gly7)oxytocin, did not affect AVP binding. These results suggested that the testis may contain the V1 receptor subtype. Studies on the intratesticular distribution of AVP receptors indicated minimal binding to cells derived from the seminiferous tubule, while most of the AVP-binding sites sediment with enriched fractions of Leydig cells after Metrizamide density gradient centrifugation. AVP-binding sites were also found in rat liver, kidney, and anterior pituitary (10.7, 2.6, and 1.7 fmol/mg protein), whereas adrenal, cerebellum, prostate, and hypothalamus were devoid of AVP-binding sites. Thus, we have demonstrated the presence of high affinity, stereospecific receptors for AVP in the interstitial cell compartment of the rat testis. These V1 receptors may mediate the direct inhibitory action of neurohypophysial hormones on testicular Leydig cell steroidogenesis.
...
PMID:Identification and characterization of arginine vasopressin receptors in the rat testis. 298 Oct 73

Separation of lung alveolar basement membranes from interstitial connective tissue protein has proved difficult, and a pure preparation of alveolar wall basement membranes (AWBM) is not available. We have modified a technique employing the detergent Triton X-100 for isolating AWBM from rat lungs by adding a step utilizing human skin collagenase (HSC), a highly purified enzyme obtained from skin fibroblasts that specifically cleaves non-basement membrane collagens. Triton extraction of both lungs yields 15-20 mg of basement membrane-enriched material referred to as crude fraction (CF). Ultrastructural studies show that CF includes both epithelial and endothelial basement membranes that appear similar to their in vivo counterparts and contain heparan sulfate proteoglycans. Extraction of type IV collagen is documented by the appearance of highly glycosylated hydroxylysine. This CF contains minimal amounts of contaminating elastin but significant amounts of interstitial collagens. CF was further purified for biochemical studies by incubation with HSC. HSC solubilized 20% of CF hydroxyproline resulting in a final fraction highly enriched in AWBM. Lung minces incubated in tritiated lysine produced a CF extract rich in newly formed type IV collagen, showing that lung tissue synthesizes AWBM collagen in vitro.
...
PMID:Isolation and characterization of a rat lung fraction enriched in alveolar wall basement membranes. 298 61

The tissue-destructive proteinases of B16-BL6 melanoma cells from C57BL/6 mice and subcellular fractions were examined. Cancer cell organelles were isolated following nitrogen cavitation with the use of sucrose density gradient centrifugation. Serine, cysteine, and metalloproteinases were assayed with the use of radiolabeled proteins and synthetic substrates. Tumor-induced red blood cell lysis was quantitated by measurement of the release of isotope from 59Fe-labeled red blood cells (RBC) cocultivated with melanoma cells; the RBC were from Wistar rats. Enzyme inhibitors with specificity toward different classes of proteinases were used in the above assays to categorize the enzymes responsible for substrate degradation. Results indicated that intact melanoma cells, cell organelles, and cytosol contain proteinases that can degrade collagen and gelatin and lyse normal RBC. Melanoma plasma membranes are highly enriched in collagenase, gelatinase, cysteine proteinase, plasminogen activator, and cytolytic activity. The inhibition of tumor collagenolytic, gelatinolytic, and cytolytic activities by EDTA and 1,10-phenanthroline but not by diisopropyl fluorophosphate and N alpha-p-tosyl-L-lysine chloromethyl ketone indicates that metalloproteinases are the active enzymes in these assays. Minocycline, a synthetic tetracycline with demonstrable inhibitory activity with other mammalian collagenases, also inhibited melanoma collagenolytic and cytolytic activities.
...
PMID:Diversity of melanoma plasma membrane proteinases: inhibition of collagenolytic and cytolytic activities by minocycline. 299 28

A series of chemical modification reactions has been carried out to identify functional constituents of the active site of human neutrophil collagenase. The enzyme is reversibly inhibited by the transition metal chelating agent 1,10-phenanthroline, and inhibition is fully reversed by zinc. Removal of weakly bound metal ions by gel filtration inactivates collagenase, and activity is fully restored on immediate readdition of calcium. The enzyme is unaffected by reagents that modify serine, cysteine, and arginine residues. However, reaction with the carboxyl reagents cyclohexylmorpholinocarbodiimide and Woodward's Reagent K lowers the activity of the enzyme substantially. Acetylimidazole inactivates the enzyme, but activity is completely restored on addition of hydroxylamine. The enzyme is also inactivated by tetranitromethane, indicating that it contains an essential tyrosine residue. Acylation of collagenase with diethyl pyrocarbonate, diketene, acetic anhydride, or trinitrobenzenesulfonate inactivates the enzyme, and activity is not restored on addition of hydroxylamine, indicating the presence of an essential lysine residue.
...
PMID:Functional constituents of the active site of human neutrophil collagenase. 301 Aug 66

Sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis of pepsin-solubilized collagens from post-burn granulation tissues revealed that type V collagen consisted of 3 alpha chains: alpha 1(V), alpha 2(V), and alpha 3(V). The mean value (0.12 +/- 0.01 SD) of the type V/type I ratio in the granulation tissues was significantly higher (p less than 0.001) than that (0.03 +/- 0.01 SD) of the ratio in normal skin. The average ratio of alpha 1(V):alpha 2(V):alpha 3(V) of type V collagen purified from the granulation tissues was determined to be about 5:3:1. SDS-polyacrylamide gel electrophoresis patterns of 3 alpha chains were not affected in the presence or absence of 2-mercaptoethanol. Purified type V collagen was degraded by bacterial collagenase, but remained intact after tadpole collagenase digestion, in contrast to type I and type III collagens. Amino acid analyses of each alpha chain separated on SDS-gel electrophoresis of type V collagen revealed that all 3 alpha chains of type V collagen were poor in alanine, rich in hydroxylysine, and had high ratios of hydroxylysine/lysine, which are typical features of type V collagen. The purified type V collagen was further fractionated by ammonium sulfate into 2 molecular species, [alpha 1(V)]2 alpha 2(V) and alpha 1(V)alpha 2(V)alpha 3(V). Our data demonstrate that type V collagen in preparations from human post-burn granulation tissues consists of 3 alpha chains and can be resolved into 2 distinct heterotrimers.
...
PMID:Isolation and characterization of type V collagen from human post-burn granulation tissues. 302 Jan 32

Calf skin and rat tendon type I, bovine cartilage type II, and human amnion type III collagens have been radiolabeled by reaction with [3H]acetic anhydride, [3H]formaldehyde, and succinimidyl 2,3-[3H]propionate. All three reactions produce collagens with high specific activities that are suitable for use as substrates in collagenase assays. The identity of the radiolabel and the labeling indices do not alter the molecular weights or thermal stabilities of the collagens or the solubilities of the collagens or gelatins in dioxane-water mixtures at 4 degrees C. However, in contrast to native or sparsely labeled collagens, those with 40 or more lysine + hydroxylysine residues labeled per molecule do not undergo fibrillogenesis in the presence of 0.2-0.4 M NaCl in the 4-35 degree C temperature range. Thus, the modification reactions not only serve to introduce the radiolabel, but also to keep the collagens soluble over a wide range of temperatures and concentrations. The TCA, TCB fragments produced on partial reaction of each collagen type with tissue collagenases can be selectively denatured by a 10-minute incubation under specific conditions and the intact collagens selectively precipitated by addition of 50% v/v dioxane. This serves as the basis for soluble collagenase assays. The effect of labeling index on the properties of the collagens has been investigated and the results establish the range of conditions over which these collagens can be used as substrates for soluble versus fibrillar collagenase assays.
...
PMID:Properties of radiolabeled type I, II, and III collagens related to their use as substrates in collagenase assays. 302 5

A suspension of renal tubule fragments from the rat was prepared by a method involving collagenase digestion of the excised renal cortex and dispersion of the digest by passage through a nylon mesh. Through the use of scanning electronmicroscopy it was confirmed that the tubular lumena were patent, thus ensuring access of medium to both the luminal and the contraluminal membranes of the tubular cells. The viability of the tubule fragments was ascertained by measuring the rate of formation of glucose from pyruvate as substrate and the uptake of [14C] L-lysine against a concentration gradient. The uptake of L-lysine was unimpaired in the presence of gentamicin (10(-3) M), suggesting that there is no competition between this basic amino acid and the polycationic aminoglycoside for transport into tubular cells. The uptake of [3H] gentamicin was studied and found to be reduced in the presence of 2,4-dinitrophenol, potassium cyanide, and ouabain. The reduced uptake in the presence of ouabain was interpreted to mean that a component of gentamicin uptake, which occurs at the luminal membrane, may be driven by the Na+ gradient created by Na+-K+ATPase activity at the contraluminal membrane. This renal tubule preparation offers advantages over the kidney-slice technique for studies into the mechanisms of aminoglycoside nephrotoxicity.
...
PMID:The use of renal tubule fragments isolated from the rat to investigate aspects of gentamicin nephrotoxicity. 308 63

Calcification is the principal cause of failure of tissue-derived cardiac valve replacements pretreated with glutaraldehyde (GLUT). The objective of this study was to determine the role of GLUT-induced cross-links in bovine pericardial tissue calcification. Various levels of 3H-GLUT incorporation were obtained by varying incubation pH, and protein modification was determined by amino acid analysis and resistance to collagenase digestion. Calcification of cross-linked tissue was studied using subdermal implants in rats. Low GLUT uptake (less than 150 nm/mg) resulted in minimal calcification (Ca2+, 12.8 micrograms/mg) and stability (4% residual weight following digestion) due to a limited crosslinking (lysine + hydroxylysine = 26.1 residues/1000 amino acids [AA]). In contrast, higher GLUT uptake induced more cross-links (Lys + Hyl = 8.2 residues/1000 AA) and consequent higher stability (95% residual wt); such tissues calcified severely (Ca2+, 93.5 micrograms/mg). Incorporation of GLUT two to three times beyond a critical level did not further enhance calcification. It is concluded that the amount of GLUT incorporated controls the extent of cross-links, which in turn directly determines tissue stability and calcification.
...
PMID:The role of glutaraldehyde-induced cross-links in calcification of bovine pericardium used in cardiac valve bioprostheses. 310 21

Morphological studies indicate that basement membrane formation or maintenance can be achieved in cultures of thyroid cells. In the present investigation we have studied the biosynthesis of this extracellular matrix by differentiated porcine thyroid cells in culture. They were prepared by two procedures: (1) thyroid cells isolated by dispase digestion of the thyroid gland were maintained in serum-free medium on poly(L-lysine) coated dishes; (2) thyroid follicles released by collagenase treatment of the gland were isolated by differential filtration and cultured in suspension on agarose-coated dishes. In both cases, functional follicular-like structures were obtained as shown by their ability to organify Na125I and to respond to thyrotropin stimulation (250 microU/ml). After incubating the cells with radiolabeled proline or methionine, collagen synthesis was observed with the two types of culture, as shown by the formation of radioactive hydroxyproline and by the synthesis of peptides with electrophoretic properties identical to those of authentic collagen molecules and susceptible to collagenase. Besides variable amounts of type I and type III collagen-like peptides, significant proportions of labeled peptides migrated with type IV collagen chains and were precipitated by anti-type IV collagen antibody; thyrotropin had no significant effect either on the total collagen synthesis or on the relative amounts of the different collagen peptides. When thyroid cells were incubated with [35S]sulfate, a labeled glycosaminoglycan with chromatographic properties analogous to that of heparan sulfate could be obtained in both culture conditions; here again, no effect of thyrotropin was observed. The ability of differentiated porcine thyroid cells to synthesize basement membrane was suggested by their production of type IV collagen and heparan sulfate, two of its potential components. Thyrotropin, which drastically enhanced the functional property of the cells, did not seem to regulate this synthesis.
...
PMID:Synthesis of basement membrane components by differentiated thyroid cells. 316 46

Structurally abnormal type I collagen was identified in the dermis, bone, and cultured fibroblasts obtained from a baby with lethal perinatal osteogenesis imperfecta. Two-dimensional gel electrophoresis of the CNBr peptides demonstrated that the alpha 1(I)CB7 peptide from the alpha 1(I)-chain of type I collagen existed in a normal form and a mutant form with a more basic charge distribution. This heterozygous peptide defect was not detected in the collagens from either parent. The defect was localized to a 224-residue region at the NH2 terminus of the alpha 1(I)CB7 peptide by mammalian collagenase digestion. Analysis of unhydroxylated collagens produced in cell culture indicated that the mutant alpha 1(I)CB7 migrated faster on electrophoresis suggesting that the abnormality may be a small deletion or a mutation that alters sodium dodecyl sulfate binding. The post-translational hydroxylation of lysine residues was increased in the CB7 peptide and also in peptides CB3 and CB8 which are toward the NH2 terminus of the alpha 1(I)-chain. The COOH-terminal CB6 peptide was normally hydroxylated. These findings support the proposal that the lysine overhydroxylation resulted from a perturbation of helix propagation from the COOH to NH2 terminus of the collagen trimer caused by the structural defect in alpha 1(I)CB7.
...
PMID:A structural mutation of the collagen alpha 1(I)CB7 peptide in lethal perinatal osteogenesis imperfecta. 355 48


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---