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PubMed2002

Leukotriene A(4)-hydrolase expression and leukotriene B(4) levels in chronic inflammation of bacterial origin: immunohistochemistry and reverse-phase high-performance liquid chromatography analysis of oral mucosal epithelium.

Chronic inflammation of the oral epithelium of bacterial origin is associated with elevated leukotriene B(4) (LTB(4)) levels. We investigated leukotriene A(4) (LTA(4))-hydrolase expression and LTB(4) levels in oral epithelium in relation to the clinical disease manifestation and immunohistopathology and LTA(4)-hydrolase expression in cultured oral keratinocytes. In 11 patients, three different types of biopsy specimens of the oral mucosa tissues were examined. Each sample was divided, and one-half was analysed using immunohistochemistry with antibodies to LTA(4)-hydrolase, CD1a, CD3, CD19, macrophages/monocytes and granulocytes. The other half of the sample was homogenised and analysed using reverse-phase high-performance liquid chromatography to determine LTB(4) levels. We found strong LTA(4)-hydrolase expression in basal cells of the oral epithelium from tissue samples that appeared clinically healthy; however, histologically a mild chronic inflammation was observed. In contrast, patients with symptoms of an inflammation of the oral mucosa showed only weak LTA(4)-hydrolase staining of the epithelial cell layers, but strong immunoreactivity in endothelial and invading inflammatory cells. LTB(4) levels were elevated in inflamed tissues compared with non-inflamed controls. Most significantly, there was a strong association between the immunohistochemical detection of the enzyme, LTB(4) levels, cellular infiltration and the clinical disease manifestations. In vitro experiments indicated that LTA(4)-hydrolase expression may be induced by bacterial contamination. This study suggests that LTA(4)-hydrolase expression and elevated LTB(4) levels in oral mucosal epithelium are integral parts of the induction and progression of chronic inflammatory reactions. Epithelial cells may participate in early stages of inflammation as a source of LTB(4).

Adult↗
PubMed1980

Lipid epoxide hydrolase in rat lung preparations.

The activity of rat lung epoxide hydrolase (epoxide hydrolase, EC 3.3.2.3) was studied using two lipid epoxides which can be isolated from lung tissue. These epoxides displayed different Km,app and hydration rates. Methyl cis-9,10-epoxystearate was hydrated 20-times more rapidly than cholest-5 alpha,6 alpha-epoxy-3 beta-ol. The Km for the lung microsomal enzyme was variable and dependent on the microsome concentration in the medium. A soluble epoxide hydrolase was also detected in both lung and liver. This enzyme appears similar to the microsomal enzyme in its activity toward methyl epoxystearate. The measured activities for liver microsomal epoxide hydrolase were over 8-times those for lung microsomes; activity against cholesterol epoxide was 40-times greater for liver. In spite of the slow rates measured with cholesterol epoxide in lung preparations, this compound was an effective competitive inhibitor against methyl epoxystearate over a wide concentration range. This suggests that cholesterol epoxide readily binds to epoxide hydrolase and is an effective competitive inhibitor against a much more actively metabolized substrate, methyl epoxystearate. Such circumstances indicate that cholesterol epoxide binds with a high degree of nonproductivity to lung microsomal epoxide hydrolase. This attribute of lung epoxide hydrolase may relate to the relatively high concentrations of cholesterol epoxide found in lung tissue.

Animals↗
PubMed1980

Acid cholesterol ester and glycerol ester hydrolase activities. Evidence for the individuality of these enzymes in human mononuclear leucocytes.

Hydrolysis of cholesterol oleate and glycerol trioleate was measured in homogenates of human leucocytes at optimum pH of 4.0 and 5.25, respectively. Both enzyme activities appeared to reside in the 15,000 x g, 20-min fraction of mononuclear leucocytes. Solubilization of cholesterol ester hydrolase activity was strongly dependent on the detergent to protein ratio, showing optimal solubilization at weight ratios of 1.0 in cell homogenates and of 3.0 in the 15,000 x g, 20-min fraction, whereas solubilization of glycerol ester hydrolase was independent to protein ratio over the tested range of 0.3 to 5.8. Using a sequential solubilization procedure, about 60% of the granule proteins as well as 88% of glycerol ester hydrolase activity were solubilized at a detergent to protein ratio of 0.3, whereas cholesterol ester hydrolase activity was solubilized from the remaining membranes at a ratio of about 3.0. Thus, the acid glycerol ester hydrolase and acid cholesterol ester hydrolase were related to different proteins. Since solubilization of cholesterol ester hydrolase required drastic treatment, it is suggested that this enzyme is related to a protein within the lysosomal membrane.

Blood Platelets↗
PubMed1987

Induction of cytosolic clofibroyl-CoA hydrolase activity in liver of rats treated with clofibrate.

Among subcellular fractions of liver homogenates of rats, the clofibroyl-CoA hydrolase activity is found mainly in the cytosolic fraction. It is here shown that the subcellular distribution of clofibroyl-CoA hydrolase appears to be different from the distribution of palmitoyl-CoA hydrolase activity. Thus, in contrast to the case with palmitoyl-CoA, no hydrolysis of clofibroyl-CoA was catalysed by the microsomal fraction. Furthermore, the hydrolysis of palmitoyl-CoA and clofibroyl-CoA in the cytosolic fraction seemed to be catalyzed by two different enzymes. Rats treated with clofibrate (0.3%, w/w) showed a significant increased clofibroyl-CoA hydrolase activity where the cytosolic hydrolase was increased 3.5-fold. Clofibrate administration also elevated the specific clofibroyl-CoA hydrolase activity by factors of 1.7 and 1.5 in the mitochondrial and the light-mitochondrial fractions, respectively. Thus, it is possible that clofibroyl-CoA hydrolase has also a multiorganelle localization.

Animals↗
PubMed1985

Leukotriene A5 is a substrate and an inhibitor of rat and human neutrophil LTA4 hydrolase.

The epoxide 5(S) trans-5,6 oxido, 7,9 trans-11,14,17 cis eicosatetraenoic acid (leukotriene A5) was chemically synthesized and demonstrated to be both a substrate and an inhibitor of partially purified rat and human LTA4 hydrolase. Both rat and human LTA4 hydrolase utilized leukotriene A5 less effectively as a substrate than leukotriene A4. Incubation of leukotriene A5 (10 microM) or leukotriene A4 (10 microM) with rat neutrophils demonstrated formation of 123 pmol LTB5/min/10(7) cells and 408 pmol LTB4/min/10(7) cells respectively. Purified rat neutrophil LTA4 hydrolase incubated with 100 microM leukotriene A5 produced 22 nmol LTB5/min/mg protein and when incubated with 100 microM leukotriene A4 produced 50 nmol LTB4/min/mg protein. Human neutrophil LTA4 hydrolase incubated with 100 microM leukotriene A5 produced 24 nmol LTB5/min/mg protein and when incubated with 100 microM leukotriene A4 produced 52 nmol LTB4/min/mg protein. Leukotriene A5 was an inhibitor of the formation of leukotriene B4 from leukotriene A4 by both the rat and human neutrophil LTA4 hydrolase. Excess leukotriene A5 prevented covalent coupling of [3H] leukotriene A4 to LTA4 hydrolase suggesting inhibition may involve covalent coupling of leukotriene A5 to the LTA4 hydrolase.

Animals↗
PubMed1984

Effects of metyrapone and norharmane on microsomal mono-oxygenase and epoxide hydrolase activities.

This study was undertaken to examine the possibility that metyrapone and norharmane stimulate epoxide hydrolase and inhibit mono-oxygenase activities by binding to a cytochrome P-450 component of a stable complex containing the two enzymes. The concentration of metyrapone and norharmane which inhibited mono-oxygenase activities of hepatic microsomes from untreated and diethylnitrosamine treated rats was lower than that required to stimulate epoxide hydrolase of the same microsomes. The ability of metyrapone and norharmane to stimulate epoxide hydrolase in these microsomes was not inhibited by the addition of carbon monoxide and reductant. Epoxide hydrolase activity was inhibited by detergents but the enzyme was still stimulated by metyrapone and norharmane under conditions of total membrane disaggregation. When microsomes were solubilized, epoxide hydrolase could be quantitatively recovered by immunoprecipitation. The immunoprecipitate contained no detectable cytochrome P-450 but was stimulated by metyrapone and norharmane. A purified epoxide hydrolase was stimulated by metyrapone but not by norharmane. The response of the enzyme to norharmane was not restored by the inclusion of cytochrome P-448. These findings suggest that metyrapone and norharmane act at separate sites on both cytochrome P-450 and epoxide hydrolase.

Alkaloids↗
PubMed1986

Distribution and nature of epoxide hydrolase activity in subcellular organelles of mouse liver.

Mouse liver light and heavy mitochondrial fractions contain significant epoxide hydrolase activity in addition to that present in the cytosol and microsomes. As the mitochondrial fraction itself contains a number of subfractions, experiments were designed to determine the localization of the epoxide hydrolase activity in these subfractions. Subcellular fractions were prepared using livers from 6- to 8-week-old Swiss-Webster male mice. Using trans-stilbene oxide (TSO) as substrate, the highest activity was localized in the cytosolic fraction, followed by the light mitochondrial fraction. Subfractionation of the light mitochondrial fraction by isopycnic sucrose density gradient resulted in the separation of mitochondria from peroxisomes as monitored by marker enzymes. The separation of these two subcellular organelles was also confirmed by the electron microscopic studies. Distribution of TSO-hydrolase activity in the sucrose density gradient fractions closely resembled the activity distribution of the peroxisomal markers catalase and urate oxidase, but significant activity was also found in mitochondria. Treatment of mice with clofibrate selectively induced TSO-hydrolase in the cytosol without affecting this enzyme activity in the peroxisomal fraction. There was no difference in the distribution pattern of TSO-hydrolase and marker enzymes in sucrose density gradients of mitochondrial fractions from clofibrate-treated and control mice. The epoxide hydrolase activity in the peroxisomes is immunologically similar to, and also has the same molecular weight as, the cytosolic epoxide hydrolase.

Animals↗
PubMed1986

Characterization of multiple epoxide hydrolase activities in mouse liver nuclear envelope.

A nuclear envelope-associated epoxide hydrolase in mouse liver that hydrates trans-stilbene oxide has been identified and characterized. This epoxide hydrolase is distinct from the enzyme in nuclear envelopes that hydrates benzo[a]pyrene 4,5-oxide and other arene oxides. This distinction was demonstrated by the criteria of pH optima, response to specific inhibitors in vitro, and precipitation by specific antibodies. The new epoxide hydrolase had a pH optimum of 6.8, was poorly inhibited by trichloropropene oxide, was potently inhibited by 4-phenylchalcone oxide, and did not bind to antiserum against benzo[a]pyrene 4,5-oxide hydrolase. This nuclear enzyme is similar in many of its properties to cytosolic and microsomal trans-stilbene oxide hydrolases and may be nuclear envelope-bound form of these other epoxide hydrolases. It differed from these other trans-stilbene oxide hydrolases in that its affinities for both trans-stilbene oxide (measured as apparent Km) and 4-phenylchalcone oxide (measured as I50) were 4- to 20-fold lower than those of either the cytosolic or microsomal forms.

Animals↗
PubMed1991

Inhibition of cytosolic epoxide hydrolase by trans-3-phenylglycidols.

The inhibition of murine cytosolic epoxide hydrolase has been studied with both racemic and enantiomerically pure trans-3-phenylglycidols. These compounds are the first enantioselective, slow binding inhibitors of cytosolic epoxide hydrolase. The (2S,3S)-3-phenylglycidol enantiomer was always a better inhibitor than the (2R,3R)-enantiomer. When the I50 values of (2S,3S)- and (2R,3R)-3-(4-nitrophenyl)glycidol were compared, the (2S,3S)-enantiomer was at least a 750-fold better inhibitor (I50 = 1.6 microM) than the (2R,3R)-enantiomer (I50 = 1200 microM), and it was the most potent inhibitor tested in the 3-phenylglycidol series. If the hydroxyl group of the glycidol was masked or converted to another functionality, the potency of the inhibitor decreased and the (2S,3S)-enantiomer was not necessarily the better inhibitor. In addition, trans-3-phenylglycidols demonstrated slow binding inhibition of cytosolic epoxide hydrolase. Inhibitors without a hydroxyl group, or with a blocked hydroxyl group, were not slow binding inhibitors. These results suggested that the hydroxyl group was important in both enantioselectivity and time dependence of inhibition of cytosolic epoxide hydrolase by trans-3-phenylglycidols. The hydration pattern of (2S,3S)- and (2R,3R)-2,3-epoxy-3-(4- nitrophenyl)glycidol by cytosolic epoxide hydrolase also differed. When incorporation of [18O] from water catalyzed by cytosolic epoxide hydrolase was measured, the (2S,3S)-enantiomer gave 12% incorporation into the benzylic carbon and the (2R,3R)-enantiometer gave 40% incorporation into the benzylic carbon. Finally, trans-3-phenylglycidols were found to be poor inhibitors of microsomal epoxide hydrolase.

Animals↗
PubMed1990

Glycosylation of lactase-phlorizin hydrolase in rat small intestine during development.

Age-specific changes in glycosylation of rat intestinal lactase-phlorizin hydrolase were analyzed using enzyme immunoprecipitated from microvillus membranes of suckling, weaning, and adult rats, and carbohydrate moieties were examined by lectin affinity binding, metabolic labeling, and neuraminidase treatment. Lectin binding indicated the presence of N-linked and O-linked oligosaccharide chains containing mannose and galactose throughout development. An age-dependent shift in sialic acid and fucose was seen during the period of weaning; no fucose was detectable in lactase-phlorizin hydrolase until after the rats were 20 days of age, whereas sialic acid was reduced in adult lactase-phlorizin hydrolase. The presence of sialic acid in suckling intestines and fucose in adult was confirmed by metabolic labeling with appropriate radioactive precursors. Sodium dodecyl phosphate-polyacrylamide gel electrophoresis analysis of immunoprecipitated lactase-phlorizin hydrolase from the proximal and mid small intestine showed two bands of approximately 220 and 130 kilodaltons in all age groups. In the distal part of the adult small intestine, lactase-phlorizin hydrolase appeared as two bands of similar size to those found in the proximal and mid portions. In contrast, during the suckling and weaning periods, these distal bands were approximately 225 and 135 kilodaltons. [35S]-methionine labeling and fluorography of neonatal intestines confirmed these observations. The size difference between proximal and distal small intestines was virtually eliminated by neuraminidase treatment. These data indicate that the core structure of microvillus membrane lactase-phlorizin hydrolase, consisting of both N-linked and O-linked oligosaccharides, remains constant during development, although terminal sugars shift from predominantly sialic acid during the suckling period to fucose in adulthood. This alteration in glycosylation of the protein occurs in a different pattern from the postweaning decline in lactase specific activity. Consequently, age-dependent changes in glycosylation cannot account for the decrease in lactase-phlorizin hydrolase-specific activity observed during development.

Aging↗
PubMed1987

Coordinate induction of peroxisomal beta-oxidation activity and cytosolic epoxide hydrolase activity.

The effect of four hypolipidemic compounds (tiadenol, clofibrate, acetylsalicylic acid, 1-benzylimidazole) on the specific activities of peroxisomal beta-oxidation and cytosolic and microsomal epoxide hydrolase of rat liver was investigated. Since specific activity of cytosolic epoxide hydrolase from outbred Sprague-Dawley rats showed large interindividual variations (approximately 38-fold), induction studies were performed with inbred Fischer F-344 rats, which showed only low interindividual variations (approximately 2-fold). Clofibrate, tiadenol and acetylsalicylic acid caused a 8-, 13- and 4.5-fold induction of cEH and a 13-, 19- and 5-fold induction of peroxisomal beta-oxidation activity, respectively. Microsomal epoxide hydrolase activity was only slightly increased (less than 1.5-fold). 1-Benzylimidazole induced both cytosolic epoxide hydrolase and peroxisomal beta-oxidation activity about 2-fold, whereas microsomal epoxide hydrolase activity was increased about 4-fold. Increase in cytosolic epoxide hydrolase activity was not due to enzyme activation as demonstrated by in vitro studies. On the other hand, these in vitro studies showed that the increase in microsomal epoxide hydrolase activity by 1-benzylimidazole may partially be due to activation of the enzyme.

Animals↗
PubMed1983

An estrogen-stimulated, calcium-dependent tosylarginine methyl ester (TAME) hydrolase in immature rat uterus.

An arginyl esterase, identified by hydrolysis of tosyl-L-arginine-O-methyl ester (TAME), is present in estrogen-stimulated, immature rat uterine cytosol. The esterase is Ca2+-dependent and appears 3-8 h after injection of 4.5 micrograms of 17 beta-estradiol (E2). The Ca2+-independent TAME hydrolase activity in stimulated uteri decreases as the Ca2+-dependent hydrolase activity increases. The TAME hydrolase activity is not increased by dexamethasone or testosterone, nor is it elevated in liver cytosol of the same E2-treated rats. Rat plasma contains a potent Ca2+-dependent TAME hydrolase activity distinguished from the uterine enzyme by its response to high Ca2+ concentrations and its interaction with goat anti-rat serum immunoglobulin G. The uterine TAME hydrolase is apparently a trypsin-like serine protease, as defined by its pattern of inhibition, e.g. response to diisopropylfluorophosphate. The Ca2+-dependent hydrolase kinetics are complex, with an initial lag phase followed by a dramatic acceleration in the rate of hydrolysis. Both the length of the lag phase and the extent of acceleration vary with the amount of cytosol. The metal requirement is specific for Ca2+. The endogenous substrate of this newly recognized, estrogen-stimulated TAME hydrolase and its role in uterine development remain to be elucidated.

Animals↗
PubMed1980

Specificity of mouse liver cytosolic epoxide hydrolase for K-region epoxides derived from polycyclic aromatic hydrocarbons.

Mouse liver cytosol epoxide hydrolase, known to be very active for certain alkene oxides, had a specific activity which was 2.1-, 11- and 160-fold lower than that of the microsomal epoxide hydrolase for the arene oxides 7-methylbenz[a]anthracene 5,6-oxide, benz[a]anthracene 5,6-oxide and phenanthrene 9,10-oxide, respectively. For benzo[a]pyrene 4,5-oxide no activity (less than 10 pmol product/mg protein/min) of cytoplasmic epoxide hydrolase was detectable. The specific activity of cytoplasmic epoxide hydrolase was much lower for all K-region epoxides investigated, compared to trans-stilbene oxide used as a positive control and for which a new assay is described. It is concluded from these rates combined with the fact that these lipophilic K-region epoxides are expected to stay preferentially at membranous sites where they are generated, that cytoplasmic epoxide hydrolase plays a minor role for their transformation compared to membrane-bound hydrolase. The data also show that for the substrates investigated the epoxide hydrolase activities in the cytoplasmic and microsomal fractions are complementary to some extent, but there is no quantitative inverse relationship.

Animals↗
PubMed1981

Effect of thyroid hormones on acid cholesterol ester hydrolase activity in rat liver, heart and epididymal fat pads.

The regulation of acid cholesterol ester hydrolase activity by thyroid hormones was studied in subcellular fractions from rat liver, heart, and epididymal fat pads; hydrolase activity was determined at pH 5 with a glycerol-dispersed cholesterol oleate substrate preparation. Acid cholesterol ester hydrolase activity was decreased in liver preparations from thyroidectomized rats relative to activity in livers from euthyroid control rats. Administration of triiodothyronine to either euthyroid or hypothyroid (thyroidectomized) rats resulted in an increase in acid cholesterol ester hydrolase activity in liver preparations. Similar effects of thyroidectomy and the administration of triiodothyronine on acid cholesterol ester hydrolase activity were observed with fat pad preparations. In contrast, no effect of thyroid hormones was observed on acid cholesterol ester hydrolase activity in heart. These results suggest that thyroid hormones may regulate the catabolism of serum lipoproteins, in part, by alterations in lysosomal acid cholesterol ester hydrolase activity in liver and epididymal fat pads.

Acetylglucosaminidase↗
PubMed2005

Epoxide hydrolases: their roles and interactions with lipid metabolism.

The epoxide hydrolases (EHs) are enzymes present in all living organisms, which transform epoxide containing lipids by the addition of water. In plants and animals, many of these lipid substrates have potent biologically activities, such as host defenses, control of development, regulation of inflammation and blood pressure. Thus the EHs have important and diverse biological roles with profound effects on the physiological state of the host organisms. Currently, seven distinct epoxide hydrolase sub-types are recognized in higher organisms. These include the plant soluble EHs, the mammalian soluble epoxide hydrolase, the hepoxilin hydrolase, leukotriene A4 hydrolase, the microsomal epoxide hydrolase, and the insect juvenile hormone epoxide hydrolase. While our understanding of these enzymes has progressed at different rates, here we discuss the current state of knowledge for each of these enzymes, along with a distillation of our current understanding of their endogenous roles. By reviewing the entire enzyme class together, both commonalities and discrepancies in our understanding are highlighted and important directions for future research pertaining to these enzymes are indicated.

Animals↗
PubMed1987

Purification of bleomycin hydrolase with a monoclonal antibody and its characterization.

We established a hybridoma clone that produced anti-bleomycin hydrolase antibody. The subclass of the monoclonal antibody was immunoglobulin M. The antibody significantly reacted with bleomycin hydrolase from rabbit tissues, mouse livers, sarcoma 180, and adenocarcinoma 755 but not significantly with that from MH 134 and Ehrlich carcinoma. The enzyme from L5178Y cells showed an intermediate reactivity. Bleomycin hydrolase was purified from rabbit liver by immunoaffinity with the monoclonal antibody and DEAE gel chromatography. Approximately 1300-fold-purified bleomycin hydrolase was obtained. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectric focusing on a polyacrylamide slab gel of purified bleomycin hydrolase showed a single band with an apparent Mr of 48K and an isoelectric pH of 5.2. The molecular weight of bleomycin hydrolase determined on gel filtration high-performance liquid chromatography was ca. 300K, suggesting a hexameric enzyme. The enzyme showed an optimum pH of 6.8-7.8 and gave a Vmax value of 6.72 mg min-1 mg-1 for peplomycin and 9.24 mg min-1 mg-1 for bleomycin B2 and a Km value of 0.79 mM for both substrates. The enzyme was inhibited by E-64, leupeptin, p-tosyl-L-lysine chloromethyl ketone, N-ethylmaleimide, Fe2+, Cu2+, and Zn2+ but was enhanced by dithiothreitol. The results suggest that bleomycin hydrolase is a thiol enzyme.

Animals↗
PubMed1997

Aflatoxin B1 8,9-epoxide hydrolysis in the presence of rat and human epoxide hydrolase.

Aflatoxin B1 (AFB1) must be activated to the electrophilic AFB1 exo-8,9-epoxide to be genotoxic and carcinogenic. A role for epoxide hydrolase in detoxication has been suggested but never directly addressed. In light of recent studies determining the instability of AFB1 exo-8,9-epoxide in H2O, a role for epoxide hydrolase appears dubious. Rat liver or recombinant rat epoxide hydrolase provided an enhancement to the already fast hydrolysis rate of up to 22%. Purified human epoxide hydrolase provided no detectable enhancement to the rate of chemical hydrolysis. Some reduction in the genotoxicity of AFB1 was observed when the ratio of rat epoxide hydrolase to cytochrome P450 was high (approximately 50-fold). An 80-fold excess of human epoxide hydrolase over cytochrome P450 only produced an effect of approximately 25% inhibition. It appears, therefore, that there is little evidence to support a role for epoxide hydrolase in the detoxication of AFB1.

Aflatoxin B1↗
PubMed1979

Effects of antimycin A and 2-deoxyglucose on secretion in human platelets. Differential inhibition of the secretion of acid hydrolases and adenine nucleotides.

1. Shape change, aggregation and secretion of dense-granule constituents in platelets differ in their dependence on cellular energy metabolism. The possibility that such a difference also exists between secretion of dense-granule constituents and acid hydrolases was investigated. 2. Human platelets were incubated with [(14)C]adenine in plasma, and then washed and resuspended in salt solutions. The effects of incubating the cells with antimycin A and 2-deoxyglucose on the concentrations of [(14)C]ATP, ADP, AMP, IMP and inosine plus hypoxanthine and on thrombin-induced secretion of ATP plus ADP and acid hydrolases were studied. The metabolic inhibitors only affected (14)C-labelled nucleotides, whereas thrombin only liberated unlabelled ATP and ADP. 3. The extent of secretion decreased progressively with time during incubation with the metabolic inhibitors. At any time the secretion of acid hydrolases, beta-N-acetylglucosaminidase, beta-glucuronidase and beta-galactosidase was inhibited to a greater extent than secretion of ATP plus ADP (dense-granule secretion). 4. Incubation with the metabolic inhibitors shifted the log (dose)-response relationship to higher thrombin concentrations, and with a greater shift for acid hydrolase secretion than for dense-granule secretion. 5. Antimycin, when present alone, caused a marked decrease in the rate of acid hydrolase secretion, but had no effect on dense-granule secretion. 6. These results further support the view that acid hydrolase secretion and dense-granule secretion are separate processes with different requirements for ATP energy. Acid hydrolase secretion, but not dense-granule secretion, appears to depend on a simultaneous rapid generation of ATP, which can be accomplished by oxidative, but not by glycolytic, ATP production.

Adenine Nucleotides↗