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)

Rat adrenal cortical cells have been prepared by collagenase dissociation of trypsin-treated adrenal tissue. The content and compositions of cholesteryl ester, phospholipid, and triglyceride fatty acids compare favorably with those of undissociated rat adrenal tissue. During 2-hour control incubations of adrenal cortical cells, steroidogenesis was not detected, and the levels of sterol ester, phospholipid, and triglyceride fatty acids were not significantly altered. Incubations with adrenocorticotropic hormone (ACTH) resulted in coricosterone production and significant depletions of sterol ester and triglyceride fatty acids, but not of phospholipid fatty acids. Although all fatty acid esters of cholesterol were hydrolyzed under these conditions, the greatest contributions to the net decrease in sterol esters were by oleate, arachidonate, and adrenate. Incubations with dibutyryl cyclic adenosine monophosphate (0.5 mM) resulted in significantly greater levels of corticosterone production than did ACTH (250 muunits), but the effects on cellular lipids were comparable to those seen with the tropic hormone. This study represents the first demonstration of hormone-induced hydrolysis of sterol esters in an in vitro cell suspension system. The results are discussed with respect to hormone-sensitive sterol ester hydrolase of adrenal cortex, and to the role of endogenous cholesteryl esters in the steroidogenic pathway.
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PMID:ACTH-induced hydrolysis of cholesteryl esters in rat adrenal cells. 20 12

Previous studies from this laboratory have documented a progressive decline in basal and ACTH-stimulated corticosterone production in isolated adrenocortical cells as rats age. In the current study we examined the possibility that the aging process exerts this effect by interfering with the mechanism(s) by which cholesterol is processed and/or synthesized by the adrenal gland. Freshly excised adrenals from 2-, 5-, 12-, and 18-month-old rats were used for the measurement of cholesteryl ester, free cholesterol, cholesteryl esterases, and acyl co-enzyme A (CoA)-cholesterol acyltransferase activities as well as key enzymes involved in cholesterol biosynthesis. The results showed that cholesteryl ester content increased in a linear manner with advancing age, while neutral cholesteryl esterase activity decreased steadily until at 18 months of age it reached 40% that of 2-month-old control rats. In contrast, lysosomal acid cholesteryl esterase did not change with age, and acyl CoA: Cholesterol acyltransferase showed only a 33% decrease at 12 months of age. The activity of 3-hydroxy-3-methylglutaryl CoA reductase, the rate-limiting enzyme in cholesterol biosynthesis, decreased steadily with advancing age, and at 18 months of age, activity was only half of that in 2-month-old control rats. In contrast, the activities of other enzymes involved in the de novo synthesis of cholesterol, namely acetoacetyl CoA thiolase and HMG CoA synthase, were similar in 2- and 12-month-old rats, while mevalonate kinase activity was significantly lower in the 12-month-old rats. After depletion of plasma lipoprotein cholesterol by 4-aminopyrazolo-[3,4-d]pyrimidine, the intraadrenal cholesteryl ester content in young and aged animals fell significantly. Furthermore, such treatment enhanced the activities of all of the cholesterol de novo synthetic enzymes examined. In addition, HMG CoA synthase and HMG CoA reductase activities rose to much greater levels in both young and old rats compared to acetoacetyl CoA thiolase and mevalonate kinase. Finally, markedly higher activities of HMG CoA reductase were observed in 12- and 18-month-old rats after 4-aminopyrazolo-[3,4-d]pyrimidine treatment. Similar results were seen using 17 alpha-ethinyl estradiol to deplete cholesterol and adrenal sterol ester stores. The metabolism of endogenous cholesterol and exogenous hydroxysterols (which bypass the cAMP-dependent transport of endogenous cholesterol to mitochondrial side-chain cleavage enzyme complex) to corticosterone by collagenase-dispersed adrenocortical cells isolated from rats of various ages were also studied.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Effects of aging on cholesterol content and cholesterol-metabolizing enzymes in the rat adrenal gland. 288 78

Cholesteryl esterase activities were determined in homogenates of rat heart (ventricles), isolated, calcium-tolerant, cardiac myocytes and aortic tissue and were compared with acid and neutral triglyceride lipase activities in these fractions. Using cholesteryl oleate/phosphatidylcholine/taurocholate emulsions and digitonin pretreatment of the enzyme fractions, acid and neutral cholesteryl esterase activities were measured in all tissue preparations. In contrast to the acid and neutral triglyceridase and acid cholesteryl esterase activity, the neutral cholesteryl esterase activity was subject to substrate inhibition. Upon isolation of cardiac myocytes, and in contrast with the recovery of neutral triglyceride lipase activity, only a small portion of the neutral cholesteryl esterase (6%) was recovered, suggesting that nonmyocyte neutral cholesteryl esterase activity markedly contributes to the relatively high activity detectable in whole ventricular homogenates. The recovery of large amounts of neutral cholesteryl esterase activity in the supernatant of collagenase-digested heart tissue, obtained during the isolation of myocytes, which is also markedly enriched in activities of two endothelial marker enzymes (5'-nucleotidase and angiotensine-converting enzyme) may indicate the predominant contribution of neutral cholesteryl esterase activity from coronary endothelial cells to this activity detectable in ventricular homogenates. Relative to the activity in ventricular and myocyte homogenates, aorta homogenates possessed the highest specific neutral cholesteryl esterase activity. We propose that in addition to coronary endothelium, smooth muscle cells also contribute to the neutral cholesteryl esterase activity in ventricular homogenates.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cholesteryl esterase activities in ventricles, isolated heart cells and aorta of the rat. 303 10

Enzyme-induced liberation of hard-segment-containing components from polyurethanes was evaluated using two 14C-labeled polyurethanes. A polyester urea-urethane and polyether urea-urethane were synthesized from toluene-2,4-diisocyanate (TDI)/polycaprolactone diol (PCL) or TDI/polyethylene glycol (PEO) with 14C-labeled ethylene diamine. Both materials were characterized using electron spectroscopy for chemical analysis (ESCA), differential scanning calorimetry (DSC), size exclusion chromatography, and material chemistry by Fourier transform infrared (FTIR) spectroscopy. Biodegradation assays were carried out using cholesterol esterase (CE), collagenase (CO), cathepsin B (CB), and xanthine oxidase (XO) at the pH optimum conditions for each enzyme at 37 degrees C. Biodegradation was analyzed by monitoring the release of radiolabel, by weight change, and by surface analysis using scanning electron microscopy. The polyester urea-urethane was shown to be susceptible to enzymatic degradation above the effect of the buffer control solution by the CE but not by the other enzyme systems as monitored by radiolabel released. In the initial period of incubation, the rate of degradation was increased for all systems, including buffer controls; however, the rates dropped off rapidly by day 28. The change in weight data for the polyester urea-urethane and polyether urea-urethane showed no enzyme-dependent biodegradation above the buffer controls. However, in sodium acetate buffer at pH = 5, the polymers showed a significant weight loss relative to other buffers. In conclusion, this study showed that the biological component responsible for the onset of the biodegradation process is more likely the result of a multitude of biologically mediated compounds acting synergistically, with the process being enhanced by physical parameters such as material dissolution. In addition characterization of surface and bulk chemistry as well as material structure evaluation have been shown to be essential to interpret degradation data.
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PMID:Enzyme-biomaterial interactions: effect of biosystems on degradation of polyurethanes. 842 Oct 4

Penetration of adhesives into the demineralized dentin surface and their subsequent conversion are critically important to longevity of the adhesive resin (AR)-dentin bond. The durability of the resin-dentin bond is investigated by monitoring the change of adhesive concentration within the hybrid layer (HL) of aged specimens using Raman spectroscopy. Absolute molar concentrations of Bis-GMA and HEMA were measured across the HL of resin-dentin specimens 24 h after photopolymerization and after 24-week storage in one of three media: artificial saliva (SAL), SAL containing cholesterol esterase to attack resin (EST), and SAL containing bacterial collagenase to attack collagen (COL). No significant difference among these groups for both Bis-GMA and HEMA molar concentrations at 24-h storage was found; however, concentrations decreased from the AR to the middle of the HL. Concentrations remained unchanged at any resin-dentin position after aging in SAL. In the HL, concentrations significantly decreased with aging in COL and tended to decrease in EST. While showing potential enzymatic biodegradative effects of endogenous matrix metalloproteinases and salivary esterases, this methodology may also prove to be a valuable assessment of new chemistries and future approaches to improve resin-dentin bond performance. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010.
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PMID:In vitro enzymatic biodegradation of adhesive resin in the hybrid layer. 2012 99