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

The acyl-CoA:sn-glycerol-3-phosphate acyltransferase (EC 2.3.1.15) (glycerol-P acyltransferase) and acyl-CoA:dihydroxyacetone phosphate acyltransferase (EC 2.3.1.42) (DHAP acyltransferase) activities were investigated in vitro in order to evaluate the quantitative contribution of the glycerol-P and DHAP pathways for the synthesis of triacylglycerols in isolated fat cells and to test the hypothesis that these two activities may be dual catalytic functions of a single enzyme. More than 85% of both acyltransferase activities was associated with the microsomal subcellular fraction. The microsomal glycerol-P acyltransferase activity showed an apparent Km of 8 muM for glycerol-P with a Vmax of 15.6 nmol/min/mg, while the DHAP acyltransferase activity showed an apparent Km of 40 muM for DHAP with a Vmax of 9.7 nmol/min/mg. Glycerol-P was a competitive inhibitor (Ki = 7.2 muM) of the DHAP acyltransferase, and DHAP was a competitive inhibitor (Ki = 92 muM) of the glycerol-P acyltransferase. The two acyltransferase activities showed virtual identity in their pH dependence, acyl-CoA chain length dependence, thermolability, and inactivation by N-ethylmaleimide. Trypsin, detergents, collagenase, phospholipases, and various salts and organic solvents also had similar effects on both activities. Taken as a whole, the data strongly suggest that the microsomal glycerol-P and DHAP acyltransferase activities actually represent dual functions of a single enzyme. Calculations based on the above kinetic constants and previously reported glycerol-P and DHAP pools in adipocytes suggest that the in vivo ratio of glycerol-P to DHAP acylation should be greater than 24:1.
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PMID:Triacylglycerol synthesis in isolated fat cells. Evidence that the sn-glycerol-3-phosphate and dihydroxyacetone phosphate acyltransferase activities are dual catalytic functions of a single microsomal enzyme. 0 98

1. Guinea-pig hepatocytes were prepared by collagenase digestion of the perfused liver. 2. The highest rates of gluconeogenesis were obtained from fructose, followed by pyruvate, xylitol and lactate, glycerol and propionate in that order. Maximum rates of gluconeogenesis were attained at 6-10mm substrate. 3. An initial 15-min lag period occurred during gluconeogenesis from lactate. This lag was abolished by preincubating the cells or by preincubation plus the addition of NH(4)Cl or lysine. 4. The lactate/pyruvate and 3-hydroxybutyrate/acetoacetate ratios were increased during the lag and adjusted to values favouring rapid gluconeogenesis from lactate after 15min. 5. The data suggest that the low glucose synthesis during the lag resulted from a limitation of the glutamate-aspartate shuttle and from the unusual redox state of the NAD(+) couple prevailing during this period. 6. At 0.1mm, amino-oxyacetate, a transaminase inhibitor, decreased gluconeogenesis from lactate by 80%, but had a negligible effect on glucose production from pyruvate. Gluconeogenesis from lactate was also inhibited (20%) by 10mm-dl-3-hydroxybutyrate.
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PMID:Gluconeogenesis by isolated guinea-pig liver parenchymal cells. 17 3

Adipocytes were prepared by collagenase digestion of rat epididymal adipose tissue and incubated for 5, 15 or 30 minutes in Krebs-Ringer bicarbonate buffer containing albumin (40 mg/ml), glucose (1 mg/ml) and epinephrine. Calcium ion was present in some incubations at concentration of 2.5 mM and omitted from others; media with no added calcium contained 1.0 mM EGTA thereby producing a final calcium concentration of less than 10(-7) M. Glycerol release and accumulation of cyclic AMP were measured. Basal lipolysis and cell cyclic AMP levels were increased slightly but not significantly when adipocytes were incubated in calcium free media. Lipolysis could be activated with epinephrine in the absence of calcium but the sensitivity of the lipolytic response was greatly reduced; however, the maximum lipolytic response to epinephrine was not decreased in calcium free media. Similarly, incubation of adipocytes in calcium free media resulted in decreased accumulation of cyclic AMP in response to epinephrine but only when sub-maximum concentrations of the catecholamine were present. Varying the extracellular calcium concentration showed that a concentration of at least 10(-5) M was optimal for epinephrine activation of lipolysis. These observations are considered in accord with the view that activation of adenylate cyclase is facilitated by calcium ion.
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PMID:The role of calcium ion in epinephrine activation of lipolysis. 18 5

In the course of healing of experimental ulcer one could observe a distinct difference between a cornea, subjected to the action of glycerol and a control one. The damage to the chemical structure of collagenous fibers was much smaller than in the control. On the basis of the investigations performed one may conclude that glycerol, through dehydration of the corneal tissue and stimulation of mucopolysaccharide synthesis, suppresses the activity of collagenase. In polarized light this process was manifested by the double refraction phenomenon and in clinical observation--by an accelerated healing of ulcer.
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PMID:Effect of dehydration of the cornea with experimentally induced ulcer on collagenase activity. 18 91

Five different cell populations, designated I to V, were isolated from minced newborn rat calveria by 5-sequential 20 min incubations with an enzyme mixture containing collagenase, elastase and DNAse. In primary culture, all five populations responded to parathyroid hormone (PTH) to a different degree, population IV giving the highest increase in cyclic-3'5'-adenosine monophosphate (cAMP) level. None of the five populations gave any response to calcitonin. Upon subsequent subcultures, all populations, except population IV, either lost or considerably decreased their response to PTH. Population IV gave a two to three-fold increase in cAMP concentration in response to PTH up to the third subculture. No morphological differences could be observed among the five populations. The third subculture of population IV cells that had been stored in 10% glycerol at -80C for four months was subsequently thawed and subcultured to the sixth subculture. These cells still responded to PTH with an increase in cAMP level. In a second experiment, 5 different cell populations designated I to V were isolated in a similar way by incubation with collagenase and DNAse. The maximum response to PTH was found in population 3. The preservation of the PTH-responsiveness of this population, after subculturing, freezing, storing in 10% glycerol at -80 C and subsequent subculturing, was likewise demonstrated. The hormone-responsiveness of cells from the sixth subculture of previously frozen and thawed population IV cells was further analyzed. These cells responded to PTH at a concentration of 0.1 U/ml to 5U/ml and to prostaglandin E1 (PGE1) at a concentration of 0.1 microng/ml to 10 microng/ml. The time course of action on population IV of PTH was found to be different from that of PGE1, suggesting a possible difference in the regulation of intracellular cAMP levels by these hormones.
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PMID:Parathyroid hormone- and prostaglandin E1-response in a selected population of bone cells after repeated subculture and storage at -80C. 19 Dec 37

A series of hydrolytic enzymes were compared with lysolecithin, glycerol monooleate, and inactivated Sendai virus for their ability to bring about the fusion of several human and mouse lymphoid cell lines. The agents were tried alone and in various combinations, and a variety of incubation conditions were tested to determine those optimal for fusion. Sendai virus was found to produce the best results with the mouse lymphoid cells; lysolecithin plus glycerol monooleate was slightly superior with the human lymphoid cells. A mixture of hyaluronidase plus collagenase produced low (2 to 6%), but significant, fusion of the human lymphoid cells; both the human and mouse lymphoid cell lines were found to contain relatively high amounts of prolyl hydroxylase, the enzyme which forms collagen from protocollagen. The maximum fusion obtained with the human cells was 16%; with a mouse plasmacytoma line, the maximum was 7.5%; and with a mouse leukemic line derived from L5178Y, the maximum was 60%.
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PMID:Optimal conditions for the fusion of lymphoid cell lines. 24 Jul 76

Adipose tissue was removed from five-day old chickens after a) an overnight fast, b) total pancreatectomy and c) partial evisceration and digested with collagenase. The adipocytes were incubated with pancreatic glucagon (Novo) and the glycerol released into the medium taken as the index of lipolytic activity. A moderate fast, while being without effect on basal lipolysis, slightly decreased adipocyte sensitivity to glucagon. Pancreatectomy and evisceration significantly reduced both basal lipolysis and the response to glucagon: the impairment was most evident just at the concentration found in the plasma of such operated animals. It seems clear that normal lipolysis is under the control not only of pancreatic factors, but also of those of intestinal origin, and can only proceed normally when both are present.
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PMID:The contribution of the pancreas and the intestine to the regulation of lipolysis in birds. 2. Impaired lipolytic activity of pancreatic glucagon in the absence of either the pancreas or the intestine in the chicken. 97 34

1. Trypsin-treated human and rat fat cells were obtained by digestion of adipose tissue with collagenase plus trypsin and their lipolytic response to insulin, catecholamines and dibutyryl cyclic AMP were compared with the lipolytic response of human and rat fat cells isolated with collagenase only. 2. In both human and rat fat cells, no significant modification occurred in the intracellular lactate dehydrogenase content and in the basal release of glycerol after trypsination. 3. In rat fat cells, trypsin abolished the antilipolytic effect of insulin but maintained a normal lipolytic response to epinephrine, norepinephrine and isoproterenol. 4. In human fat cells, on the contrary, trypsin failed to modify the antilipolytic effect of insulin, but markedly potentiated the lipolytic response to epinephrine, norepinephrine and isoproterenol. Trypsin also increased the rate of intracellular 3' :5' cyclic AMP accumulation in response to catecholamines. Under these conditions, however, trypsin-treated human fat cells had a normal reponse to the lipolytic agent dibutyryl cyclin AMP. 5. These data suggest that human fat cells differ from the rat ones by the existence in human adipocyte membranes of a trypsin-sensitive component which inhibits the catecholamine induced lipolytic process and which is different from the alpha receptors.
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PMID:Influence of trypsin on lipolysis in human fat cells. Comparison with rat adipocytes. 100 93

Intestinal epithelial cells were prepared from fasted rats by dispersion with collagenase (EC 3.4.24.3). The structural and metabolic integrity of the cells was verified by electron microscopy, a high percentage of Trypan Blue exclusion, a low degree of release of lactate dehydrogenase (EC 1.1.1.27) in the medium, and by the retention of sensitivity to agents known to modify metabolic and transport activity in everted sacs of intestinal mucosa. The isolated intestinal epithelial cells were used to study glycerolipid biosynthesis from glucose, glycerol, 2-monoacylglycerol, and free fatty acids. The cells actively incorporated the labeled precursors into glycerolipids without specific cofactor requirements. Addition of fatty acids stimulated the incorporation of both glucose and glycerol into triacylglycerols and glycerophospholipids, the greatest effect being observed with palmitate. The stimulation of monoacylglycerol acylation appeared to depend on both the nature of the monoacylglycerol and fatty acid supplied. Stereospecific analyses of the diacylglycerols formed from 2-monoacylglycerols and free fatty acids showed that 1,2-diacyl-sn-glycerols (62-70%) were the major and that 2,3-diacyl-sn-glycerols (30-38%) the minor intermediates in triacylglycerol biosynthesis. The data indicate that isolated intestinal epithelial cells exhibit a total capacity of glycerolipid synthesis and a stereochemical course of reaction which is comparable to that observed for triacylglycerol formation in everted sacs of intestinal mucosa, but much less specific than that seen in microsomal preparations of intestinal mucosa.
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PMID:Glycerolipid biosynthesis in isolated rat intestinal epithelial cells. 118 87

Besides exerting its own lipolytic effect, growth hormone (GH) has been reported to potentiate the lipolytic response of adipose tissue to epinephrine. It was thought interesting to find out whether long-term recombinant human growth hormone (rhGH) administration modifies epinephrine-induced lipolysis in isolated adipocytes of GH-deficient adults. In a double-blind protocol, GH-deficient subjects received either 6 mo placebo (controls, n = 5) or 6 mo rhGH (treated, n = 5). Biopsies of fat were obtained from the periumbilical region before and after placebo or rhGH administration. The response of the collagenase-isolated fat cells to various concentrations of epinephrine was assessed by glycerol release, measured by bioluminescence. Epinephrine-induced lipolysis was not altered by 6 mo placebo, while it was significantly increased by 6 mo rhGH. A similar response was obtained with isoproterenol, but no significant differences occurred in either group with UK 14304, an alpha 2-adrenoreceptor agonist. Thus, in GH-deficient adults, long-term rhGH administration improves the lipolytic response of isolated adipocytes to epinephrine, essentially by increasing the efficiency of the beta-adrenergic pathway.
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PMID:Effect of long-term rhGH administration in GH-deficient adults on fat cell epinephrine response. 141 26


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