Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Procollagen, the triple-stranded precursor of chick embryo skull bone collagen, contains two pro alpha1 and one pro alpha2 chains. We find that each of these is a collagen chain with both an NH2-terminal and a COOH-terminal extension peptide. The NH2-peptide of pro alpha1 contains cysteine and differs from the NH2-peptide of pro alpha2. The three NH2-peptides are cut off, giving a disulfide-linked intermediate, named altered procollagen; then the disulfide-linked COOH-peptides, which contain cysteine and tryptophan, are cut off, leaving collagen. Procollagen, altered procollagen, and COOH-peptide were isolated. Collagenase digestion of procollagen gave both NH2- and COOH-peptides, while altered procollagen gave only COOH-peptides. The following results of sequential, in vitro labeling at 37 degrees and of specific cleavage of procollagen proved the structure: [(NH2-peptide)-collagen-(COOH-peptide)]3 with interstrand S-S links between only the COOH-peptides. (i) The COOH-peptides of pro alpha chains were labeled with [3H]proline before the remainders of the chains; (ii) [35S]cysteine appeared in the COOH-peptides of completed covalent molecules 5 min earlier than in the NH2-peptides; (iii) tadpole tail collagenase, which cuts native collagen into triple-stranded 3/4 pieces containing the NH2 termini and 1/4 pieces containing the COOH ends, cuts procollagen into 3/4 pieces with NH2-peptides attached and 1/4 pieces attached to the disulfide-linked COOH-peptides. The COOH-peptides of pro alpha 1 and pro alpha2 were labeled in a 2:1 ratio at 4 min, indicating simultaneous translation of pro alpha1 and pro alpha2.
 ...
PMID:Procollagen: biological scission of amino and carboxyl extension peptides. 106 Oct 79

Type I procollagen secreted by matrix-free cells from chick embryo tendons was purified by DEAE-cellulose chromatography. Electron microscopy of segment-long-spacing aggregates of the procollagen demonstrated the presence of both NH2-terminal and COOH-terminal extensions not found in collagen. The procollagen was digested with bacterial collagenase and the COOH-terminal fragments were isolated by gel filtration and polyacrylamide gel electrophoresis in sodium dodecyl sulfate. Analysis of tryptic peptides demonstrated that the COOH-terminal extensions on the pro alpha 1 and pro alpha 2 chains had different primary structures.
 ...
PMID:Segment-long-spacing aggregates and isolation of COOH-terminal peptides from type I procollagen. 106 85

Using an in vitro rabbit pancreas system, we studied the effect of monoamine oxidase (MAO) inhibitors on flucose-stimulated insulin secretion. We evaluated the effect of both brief (15 min) and prolonged (60 min) exposure of pancreas segments to non-hydrazine (harmine, alpha-methyltryptamine, tranylcypromine and pargyline) and hydrazine (phenelzine, nialamide, iproniazid) type MAO inhibitors. All of the hydrazine type MAO inhibitors potentiated glucose-stimulated insulin secretion. Of the non-hydrazine inhibitors, only harmine and alpha-methyltryptamine potentiated glucose-stimulated insulin secretion. Hydrazine, although not itself an MAO inhibitor, also potentiated insulin secretion. Sixty minutes of exposure to tranylcypromine or alpha-methyltryptamine caused a decrease in insulin secretion. These MAO inhibitors are primary amines and primary amines can inhibit insulin secretion. The dopamine (DA) or serotonin (5-HT) content of the B-cells was increased by incubating rabbit pancreas with L-3, 4-dihydroxyphenylalanine (L-Dopa) or 5-hydroxytryptophan (5-HTP) for forty-five minutes prior to stimulation with glucose. Non-hydrazine MAO inhibitors increased dopamine inhibition of insulin secretion and either did not alter, or decreased serotonin inhibition of insulin secretion. Rabbit pancreatic islets were isolated using the collagenase digestion technique. The MAO activity of islet homogenates was determined using 5-HT and DA as substrates. Rabbit islet MAO has only one-tenth the specific activity against 5-HT (35 +/- 8.7 mumumoles/mg/min, M +/- SEM) that it has against DA (357 +/- 62.3 mumumoles/mg/min). This suggests that one reason that MAT inhibitors do not increase serotonin inhibition of insulin secretion is because MAO is not the major pathway for 5-HT inactivation in rabbit pancreatic islets. These studies suggest that MAO inhibitors alter insulin secretion, by both decreasing B-cell monoamine degradation and by mechanisms that do not involve MAO inhibition.
 ...
PMID:Monoamine oxidase inhibitors: nature of their interaction with rabbit pancreatic islets to alter insluin secretion. 110 23

A previously unknown collagen cDNA clone, PF19, was isolated from a human placenta library. The 2.1-kilobase insert has a complete open reading frame of 709 amino acids that includes 12 amino acids of the NH2-terminal domain, a principally collagenous region of 577 residues, and 120 residues of the noncollagenous COOH terminus. The collagenous part of the sequence encoded by PF19 is characterized by 13 interruptions ranging in size from 2 to 45 amino acids. Within four interruptions are consensus sequences for attachment of serine-linked glycosaminoglycans and asparagine-linked oligosaccharides suggesting that this collagen may be extensively glycosylated. A synthetic decapeptide representing a sequence at the beginning of the COOH-terminal noncollagenous domain was used to prepare an antibody in rabbits. This antiserum detected a 125-kDa bacterial collagenase-sensitive protein in Western blots of HeLa cell lysate. Consistent with the size of the collagen chain, Northern blot hybridization revealed a major transcript of 5.3 kilobases and two minor ones of 4.7 and 4.4 kilobases that are present in cultured human fibroblasts but absent from umbilical vein endothelial cells. We propose that the previously unidentified polypeptide described in this report be designated the alpha 1 chain of type XV collagen.
 ...
PMID:Identification of a previously unknown human collagen chain, alpha 1(XV), characterized by extensive interruptions in the triple-helical region. 127 71

The interaction between human fibroblast collagenase and five mammalian alpha-macroglobulins (human alpha 2-macroglobulin and pregnancy zone protein, rat alpha 1- and alpha 2-macroglobulin and rat alpha 1-inhibitor 3) is discussed. Complex formation involves specific limited proteolysis in the alpha-macroglobulin bait regions, activation of the internal beta-cysteinyl-gamma-glutamyl thiol esters, conformational changes and covalent complex formation. For human alpha 2-macroglobulin, and rat alpha 1-macroglobulin and alpha 2-macroglobulin it is estimated that the overall rate constant of complex formation is greater than 1.10(6) M-1s-1, while it is much lower for human pregnancy zone protein and rat alpha 1-inhibitor 3. More than 95% of the complexed collagenase is covalently bound. The identification of the sites of specific limited proteolysis in the bait regions of the five alpha-macroglobulins shows that cleavage may take place in sequences that are not related to those identified earlier in the collagens. These results greatly expand the repertoire of sequences known to be cleaved by fibroblast collagenase, and suggest that this proteinase has a primary substrate specificity resembling that of the microbial proteinase thermolysin as it preferentially cleaves at the NH2-terminal side of large hydrophobic residues. In addition, the results highlight the unique structure of the flexible alpha-macroglobulin bait region in that it can accommodate a conformation required by the highly restrictive fibroblasts collagenase. It is suggested that alpha-macroglobulins may play an important role in locally controlling the activity of collagenases and perhaps other proteinases of the extracellular matrix.
 ...
PMID:Localization of cleavage sites for human fibroblast collagenase in the bait region of five mammalian alpha-macroglobulins. 128 61

A strategy is described for the rapid optimization of kcat/Km for protease substrates. Selected positions of a given peptide substrate sequence are varied through synthesis with mixtures of amino acids. Incubation of the resulting peptide mixture with the enzyme of interest and analysis by high pressure liquid chromatography provides a direct measure of analogs with enhanced kcat/Km. High performance liquid chromatography/continuous flow fast atom bombardment mass spectrometry is used to assign structure to each peak in the chromatogram. As an example of the utility and efficiency of "substrate mapping" we describe optimization of the collagenase substrate Dnp-Pro-Leu-Gly-Leu-Trp-Ala-D-Arg-NH2 (where Dnp is dinitrophenyl) at the P'1 and P'2 positions. Six different mixtures were prepared for evaluation, representing the synthesis of 128 different synthetic substrates. "Substrate mapping" has led to Dnp-Pro-Leu-Gly-Cys(Me)-His-Ala-D-Arg-NH2, a substrate that possesses a 10-fold better kcat/Km than Dnp-Pro-Leu-Gly-Leu-Trp-Ala-D-Arg-NH2.
 ...
PMID:Rapid optimization of enzyme substrates using defined substrate mixtures. 130 83

Matrix metalloproteinase 9 (MMP-9) has been purified as an inactive zymogen of M(r) 92,000 (proMMP-9) from the culture medium of HT 1080 human fibrosarcoma cells. The NH2-terminal sequence of proMMP-9 is Ala-Pro-Arg-Gln-Arg-Gln-Ser-Thr-Leu-Val-Leu-Phe-Pro, which is identical to that of the 92-kDa type IV collagenase/gelatinase. The zymogen can be activated by 4-aminophenylmercuric acetate, yielding an intermediate form of M(r) 83,000 and an active species of M(r) 67,000, the second of which has a new NH2 terminus of Met-Arg-Thr-Pro-Arg-(Cys)-Gly-Val-Pro-Asp-Leu-Gly-Arg-Phe-Gln-Thr- Phe-Glu. Immunoblot analyses demonstrate that this activation process is achieved by sequential processing of both NH2- and COOH-terminal peptides. TIMP-1 complexed with proMMP-9 inhibits the conversion of the intermediate form to the active species of M(r) 67,000. The proenzyme is fully activated by cathepsin G, trypsin, alpha-chymotrypsin, and MMP-3 (stromelysin 1) but not by plasmin, leukocyte elastase, plasma kallikrein, thrombin, or MMP-1 (tissue collagenase). During the activation by MMP-3, proMMP-9 is converted to an active species of M(r) 64,000 that lacks both NH2- and COOH-terminal peptides. In addition, HOCl partially activates the zymogen by reacting with an intermediate species of M(r) 83,000. The enzyme degrades type I gelatin rapidly and also cleaves native collagens including alpha 2 chain of type I collagen, collagen types III, IV, and V at undenaturing temperatures. These results indicate that MMP-9 has different activation mechanisms and substrate specificity from those of MMP-2 (72-kDa gelatinase/type IV collagenase).
 ...
PMID:Matrix metalloproteinase 9 (92-kDa gelatinase/type IV collagenase) from HT 1080 human fibrosarcoma cells. Purification and activation of the precursor and enzymic properties. 140 Apr 81

Hydrolysis of arginine into urea and ornithine (Orn) was observed to take place in several segments of the rat nephron including cortical and medullary pars recta of the proximal tubule (PST) and collecting duct (CD). This work was now extended to the adult mouse and rabbit. Representative nephron segments, obtained by microdissection of collagenase-treated kidneys, were incubated with L-[guanido-14C]arginine (216 microM). Addition of urease produced 14CO2 + 2 NH3 from the newly formed urea released in the incubate. 14CO2 was trapped in KOH and counted. In both species, as well as in the rat, the PST was the site of the highest urea + Orn production, with an intensity increasing from cortex to medulla. For other nephron segments, the pattern was not similar in all species. Significant production of urea + Orn was observed in the proximal convoluted tubule and the medullary thick ascending limb in the rabbit, but not in the CD of either the rabbit or the mouse. The functional significance of this urea + Orn production remains unclear. The total amount of urea generated intrarenally by this reaction does not seem sufficient to play a significant role in the urinary concentrating mechanism. It may be assumed that Orn could be further metabolized to polyamines and play a role in maintaining cell integrity and function in the PST, especially in its medullary part, exposed to hypertonicity and poor oxygen supply.
 ...
PMID:Localization of urea and ornithine production along mouse and rabbit nephrons: functional significance. 144 76

The zymogens of matrix metalloproteinase 1 (MMP-1: tissue collagenase), MMP-2 (gelatinase/type IV collagenase) and MMP-3 (stromelysin) were purified from the culture medium of human rheumatoid synovial fibroblasts and the mechanisms of activation of each zymogen by proteinases and 4-aminophenylmercuric acetate (APMA) were studied by kinetic and sequence analyses. The treatment of proMMP-1 (M(r) = 52,000) with proteinases or APMA converted the zymogen to M(r) = 43,000, but it exhibited only 14-25% of the maximal activity. Incubation of a partially active MMP-1 with MMP-3 resulted in rapid, full activation by generating the 41,000-M(r) MMP-1 with Phe81 as the NH2-terminus. MMP-3 directly activated proMMP-1 by cleaving the Gln80-Phe81 bond, but this reaction was extremely slow, indicating that the Gln80-Phe81 bond is not readily available to MMP-3 in the native proMMP-1 molecule. ProMMP-2 (M(r) = 72,000) was activated only by APMA, but not by proteinases. The activation by APMA was rapid and generated an active MMP-2 of M(r) 68,000, but the enzymic activity declined rapidly after activation by autolysis. The NH2-terminal sequence analysis of active MMP-2 indicated that the Asn80-Tyr81 bond was cleaved upon APMA treatment. In contrast, proMMP-3 (M(r) = 57,000) was activated by a variety of proteinases with different specificities. The initial attacks of these proteinases are on a stretch of highly charged groups at the position 34-39 in the propeptide.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Activation mechanisms of the precursors of matrix metalloproteinases 1, 2 and 3. 148 33

(7-methoxycoumarin-4-yl)Acetyl-Pro-Leu-Gly-Leu-(3-[2,4-dinitrophenyl]-L- 2,3-diaminopropionyl)-Ala-Arg-NH2 (Mca-Pro-Leu-Gly-Leu-Dpa-Ala-Arg-NH2) has been synthesised as a fluorogenic substrate for the matrix metalloproteinases. The highly fluorescent 7-methoxycoumarin group is efficiently quenched by energy transfer to the 2,4-dinitrophenyl group. The punctuated metalloproteinase (PUMP, EC 3.4.24.23) cleaves the substrate at the Gly-Leu bond with a 190-fold increase in fluorescence (lambda cx 328 nm, lambda cm 393 nm). In assays of the human matrix metalloproteinases. Mca-Pro-Leu-Gly-Leu-Dpa-Ala-Arg-NH2 is about 50 to 100 times more sensitive than dinitrophenyl-Pro-Leu-Gly-Leu-Trp-Ala-D-Arg-NH2 and continuous assays can be made at enzyme concentrations comparable to those used with macromolecular substrates. Specificity constants (kcat/Km) are reported for both synthetic substrates with PUMP, collagenase, stromelysin and 72 kDa gelatinase.
 ...
PMID:A novel coumarin-labelled peptide for sensitive continuous assays of the matrix metalloproteinases. 153


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