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Peters TJ. Subcellular fractionation of the enterocyte with special reference to peptide hydrolases. CIBA FOUNDATION SYMPOSIUM 2008:107-22. [PMID: 4349643 DOI: 10.1002/9780470719879.ch8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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PORTEOUS JW, CLARK B. THE ISOLATION AND CHARACTERIZATION OF SUBCELLULAR COMPONENTS OF THE EPITHELIAL CELLS OF RABBIT SMALL INTESTINE. Biochem J 1996; 96:159-71. [PMID: 14343125 PMCID: PMC1206917 DOI: 10.1042/bj0960159] [Citation(s) in RCA: 184] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
1. Homogenization of the epithelial cells of rabbit small intestine in 0.3m-sucrose-5mm-EDTA, pH7.4, maintains intact the microvillus sheets that form the lumenal surface of the cells, the nuclei, the mitochondria and the vesicles (microsomes) formed from the endoplasmic reticulum. 2. These particulate components of the cell, and the cell-sap fraction, have been isolated by differential centrifuging of cell homogenates. 3. The nuclei and microvillus sheets sediment together and it has been impossible to separate these subcellular components by centrifugal methods. 4. The isolated subcellular fractions have been identified by a combination of light-microscopic examination, electron-microscopic examination, chemical analysis and assay for selected enzyme activities.
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Fujita M, Ohta H, Uezato T. Characterization of brush borders purified in iso-osmotic medium and microvillar membranes subfractionated from mouse small intestine. Biochem J 1981; 196:669-73. [PMID: 7317008 PMCID: PMC1163084 DOI: 10.1042/bj1960669] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Brush borders free of nuclei were isolated by repeated homogenization and centrifugation in iso-osmotic medium. They showed typical morphology under electron microscopy. The mean recovery and enrichment of alkaline phosphatase activity in the brush-border fraction were 50% and 17.5-fold respectively. gamma-Glutamyl transpeptidase showed a close parallelism with alkaline phosphatase and sucrase in subcellular distribution. Microvillar membranes were purified from isolated brush borders; they showed a further enrichment for alkaline phosphatase and were composed of homogeneous vesicles. Both brush-border and microvillar-membrane preparations were analysed for contamination by basolateral and endoplasmic-reticular membranes. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis of the microvillar-membrane preparation in six different systems revealed approx. 40 components in the mol.wt. range 15 000-232 000. They were grouped into seven major classes on the basis of molecular weight and electrophoretic patterns.
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Wells GP, Nicholson JA, Peters TJ. Subcellular localisation of di- and tripeptidases in guinea pig and rat enterocytes. BIOCHIMICA ET BIOPHYSICA ACTA 1979; 569:82-8. [PMID: 465509 DOI: 10.1016/0005-2744(79)90083-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Enterocytes were isolated from rat and guinea pig jejunum and subcellular fractions were prepared by density gradient centrifugation. Gradient fractions were assayed for principal organelle marker enzymes and for di- and tripeptidases. The hydrolases showed a dual localisation with both brush border and cytosol components. In the rat, approximately equal portions of dipeptidase activities were found in the two fractions but, in the guinea pig, three times more activity were found in the two fractions but, in the guinea pig, three times more activity was found in the soluble than in the brush border fractions. Cytosol components in the rat were markedly inhibited by p-hydroxymercuribenzoate. In both species tripeptidase, leucyl-2-naphthylamidases and gamma-glutamyltransferase activities were found predominantly in the brush border fractions.
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Zorzopulos J, Reich CI, Galassi N. Boophilus microplus: characterization of larval phosphomonoesterases and isolation of subcellular fractions with high phosphatase activity. Exp Parasitol 1978; 45:128-38. [PMID: 78858 DOI: 10.1016/0014-4894(78)90052-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Abstract
In order to investigate the source of free amino acids found in the gut lumen during absorption of dipeptides, as well as evaluating the role of brush border peptidases in the mucosal hydrolysis of dipeptides during absorption, rates of dipeptide disappearance and appearance of hydrolytic products were measured during perfusion of rat jejunum and ileum in vivo with buffered and unbuffered 10 mM solutions of glycl-L-phenylalanine (Gly-Phe) and L-phenylalanyl-glycine (Phe-Gly). Mucosal brush border peptidase activity was then measured in the perfused segments in vitro at luminal pH and at two substrate concentrations. In addition cytosol peptidase activity in the perfused segments was measured at pH 7-4 and at 10 mM substrate concentrations. In the jejunum, there was a relationship between rates of free phenylalanine appearance in vivo (Phe-Gly greater than Gly-Phe) and rates of brush border (Phe-Gly greater than Gly-Phe) rather than cytosol (Gly-Phe greater than Phe-Gly) peptidase activities. No constant relationship between free phenylalanine appearance and hydrolysis of the dipeptides by either brush border or cytosol peptidases was observed in the ileal studies. These findings suggest that, in the jejunum, hydrolytic products originate from the surface of the cell whereas, in the ileum, hydrolytic products originate from both the intracellular compartment as well as from the surface of the mucosal cell. In the jejunum, in vitro rates of brush border hydrolysis of Gly-Phe were always less than in vivo disappearance rates, whereas rates of Phe-Gly brush border hydrolysis always exceeded luminal disappearance rates. These data imply that Gly-Phe is predominantly transported intact and hydrolysed by cytosol peptidases, In contrast, brush border peptidases play an importnat role in the mucosal hydrolysis of Phe-Gly.
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Stegink LD. Absorption, utilization, and safety of aspartic acid. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH 1976; 2:215-42. [PMID: 11355 DOI: 10.1080/15287397609529428] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The dicarboxylic amino acids, asparate and glutamate, occupy unique positions in intermediary metabolism, particularly in the mitochondria, where they play important roles in nitrogen and energy metabolism. Administration of large quantities of glutamate and asparate to the newborn mouse produces a variety of neurotoxic effects, the most marked of which is neuronal necrosis. Neurotoxic effects of glutamate and aspartate in animal species other than the rodent are highly controversial. In the most critical animal species, the infant subhuman primate, at least four research groups have failed to duplicate the original report of glutamate-induced neuronal necrosis. Marked elevations in plasma glutamate or aspartate must occur for development of neuronal necrosis. In the highly sensitive neonatal mouse, plasma glutamate plus plasma aspartate levels must reach 60-80 mumol/dl to produce even minimal neuronal necrosis. In the healthy neonatal primate, loads producing plasma glutamate levels ranging from 50 to 1,600 mumol/dl failed to produce neuronal necrosis in our studies. Thus, it is clear that (1) marked elevations in plasma glutamate and aspartate must occur for neuronal necrosis, and (2) threshold levels required to produce neuronal necrosis vary greatly with species. The available data indicate little danger to the healthy primate and humans from ingestion of the dicarboxylic amino acids under anything resembling a reasonable intake. However, there is no doubt that these amino acids are toxic to the neonatal mouse at high dose levels.
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Wojnarowska F, Gray GM. Intestinal surface peptide hydrolases: identification and characterization of three enzymes from rat brush border. BIOCHIMICA ET BIOPHYSICA ACTA 1975; 403:147-60. [PMID: 240425 DOI: 10.1016/0005-2744(75)90018-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Peptide hydrolases were solubilized from rat small intestinal brush border by papain and separated by Sephadex G-200 chromatography, velocity gradient ultracentrifugation and polyacrylamide disc electrophoresis and designated according to approximate molecular size from sedimentation studies. Peptidases I (apparent Mr 230 000) and II (apparent Mr 160 000) are oligopeptidases with maximum specificity for tripeptides with identical pH optima (7.5) and similar apparent Km with L-Leu-Gly (I, 0.60 MM; II, 0.76 mM). L-Leucyl-beta-naphthylamide is a competitive inhibitor of both enzymes. Concentration of peptidase II produced partial conversion to peptidase I on polyacrylamide disc electrophoresis. The third peptide hydrolase (III, Mr 120 000) is a dipeptidase with pH optimum 8.5 and apparent Km for L-Leu-Gly of 0.65 mM. These peptide hydrolases were inhibited appreciably (37-59%) by 0.2 M glycine/NaOH, Tris - HCl or Tris - glycine buffers. EDTA (5 mM) completely inhibited these enzymes but all activity was restored by dialysis against buffer without divalent ions. Subsequent addition of Mg2+, Mn2+, Co2+ or Zn2+ (1-2 mM) inhibited peptidases I and II variably (4-81%) depending upon the substrate and buffer used. In contrast peptidase III was activated slightly by metal ions (5-20%). These peptide hydrolases are strategically located at the intestinal lumen-cell interface and possess biochemical characteristics making them ideally suited to play a pivotal role in the final stage of protein digestion.
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11
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Corrigendum. Br J Nutr 1975. [DOI: 10.1017/s0007114575000049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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12
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Rolls BA. Dipeptidase activity in the small intestinal mucosa during pregnancy and lactation in the rat. Br J Nutr 1975; 33:1-9. [PMID: 1115750 DOI: 10.1079/bjn19750003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
1. Rats were mated and at weekly intervals during pregnancy and lactation, and after weaning, the dipeptidase activity in the supernatant fraction from small intestinal mucosa extracts was determined for two dipeptides: glycyl-L-leucine dipeptidase (EC 3.4.3.2) AND L-alanyl-L-glutamic acid dipeptidase. 2. Dipeptidase activity is found mainly in the soluble (spernantant) fraction of the mucosa homogenate. 3. Compared with those values obtained for unmated controls, the food consumption of the animals and the nitrogen content, total and specific activities of the dipeptidases (per unit quantity of N) in the soluble fraction of the small intestinal mucosa extracts increased slightly during pregnancy and markedly during lactation. After the pups were weaned, values for all these measurements fell rapidly. 4. Whether the increases found in enzyme activity were simply a response to increased food intake or were the result of hormonal stimulus is discussed.
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Gabrielescu E. Structural integration of neuroprotease activity. INTERNATIONAL REVIEW OF NEUROBIOLOGY 1975; 17:189-239. [PMID: 237847 DOI: 10.1016/s0074-7742(08)60210-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Flanagan PR, Zbarsky SH. Phosphodiesterase II in epithelial cells from guinea-pig and rat small intestine. Biochem J 1974; 142:545-53. [PMID: 4377208 PMCID: PMC1168318 DOI: 10.1042/bj1420545] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Phosphodiesterase II activity was determined by using a synthetic substrate, the 2,4-dinitrophenyl ester of thymidine 3'-phosphate. The enzyme activity was determined in fractions obtained by differential centrifugation of homogenates of epithelial cells from the small intestinal mucosa of guinea pigs and rats. In guinea-pig preparations phosphodiesterase II occurred with highest specific activity in those fractions rich in succinate dehydrogenase and acid phosphatase. A lysosomal location for the guinea-pig enzyme was indicated by its structure-linked latency and by its association with particles that under-went a characteristic decrease in equilibrium density when Triton WR-1339 was injected into the animals. With rat preparations a much greater proportion of the phosphodiesterase II activity was found in the soluble fraction after ultracentrifugation. The rat enzyme exhibited a lower degree of latency and administration of Triton WR-1339 had no effect. The rat enzyme further differed from that of the guinea pig in other respects; it was more labile at 60 degrees C, it exhibited a lower pH optimum and it had a higher molecular weight as determined by gel-filtration chromatography.
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Maroux S, Louvard D, Baratti J. The aminopeptidase from hog intestinal brush border. BIOCHIMICA ET BIOPHYSICA ACTA 1973; 321:282-95. [PMID: 4750768 DOI: 10.1016/0005-2744(73)90083-1] [Citation(s) in RCA: 297] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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17
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Louvard D, Maroux S, Baratti J, Desnuelle P, Mutaftschiev S. On the preparation and some properties of closed membrane vesicles from hog duodenal and jejunal brush border. BIOCHIMICA ET BIOPHYSICA ACTA 1973; 291:747-63. [PMID: 4633151 DOI: 10.1016/0005-2736(73)90478-1] [Citation(s) in RCA: 102] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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18
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Fujita M, Parsons DS, Wojnarowska F. Oligopeptidases of brush border membranes of rat small intestinal mucosal cells. J Physiol 1972; 227:377-94. [PMID: 4630517 PMCID: PMC1331201 DOI: 10.1113/jphysiol.1972.sp010038] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
1. The properties of peptidases located in the brush borders of rat small intestinal mucosal cells have been investigated using a new method for the assay of peptidase activity. In this method amino acids produced by hydrolysis of peptides are oxidized by ophidian L-amino acid oxidase and the hydrogen peroxide produced during reoxidation of the reduced enzyme is estimated spectrophotometrically.2. 10-20% of the total cellular peptidase activity and 50% of the leucylnaphthylamidase (LNAase) activity were found to be tightly bound to the brush borders and to possess different substrate specificity from the supernatant peptidase activity.3. Evidence from kinetic and competition studies indicates the presence of more than one peptidase in the brush borders. The peptidases exhibit pH optima of 8.0-8.5, are inhibited by EDTA, but are not usually activated by divalent metal ions. The brush border peptidases hydrolyse di- and tripeptides, some oligopeptides, leucinamide and leucyl-beta-naphthylamine. On the basis of the Michaelis constants, these substrates differ in their affinities for the enzymes.4. It is proposed that the brush border peptidases serve an analogous function in the terminal stages of protein digestion to that of the disaccharidases in the case of carbohydrate digestion and absorption.
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Kim YS, Birtwhistle W, Kim YW. Peptide hydrolases in the bruch border and soluble fractions of small intestinal mucosa of rat and man. J Clin Invest 1972; 51:1419-30. [PMID: 5024039 PMCID: PMC292279 DOI: 10.1172/jci106938] [Citation(s) in RCA: 108] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Peptide hydrolases, catalyzing the hydrolysis of 13 dipeptides and 5 tripeptides into their respective amino acids, were studied in small intestinal mucosa and other tissues, in man and in the rat. Studies on the subcellular distribution of these enzymes showed enzyme activities in both the soluble and brush border fractions of the rat small intestinal mucosa, the former constituting 80-90% and the latter 10-15% of the total activity. Zymogram studies of peptide hydrolases, in both fractions, yielded multiple bands indicating multiple zones of enzyme activity. With most substrates a rather broad range of enzyme activities was observed in the soluble fraction differing only slightly from substrate to substrate, the exception being when L-leucyl-L-proline was used: this latter led to a zymogram pattern which was quite distinct. The synthetic substrates, L-leucyl-beta-naphthylamide and L-leucinamide appeared to be hydrolyzed by two electrophoretically distinct enzymes, different from those hydrolyzing other leucyl-containing peptide substrates. Zymogram patterns of the brush border membrane fraction were quite different from those of the soluble fraction of rat small intestine indicating that enzymes from the two sources may be different. No comparable human data were obtained.Peptide hydrolases in the soluble fractions of various organs from the same species gave similar zymogram patterns, while those from the plasma membrane-bound fractions of different organs in the same species were peculiar to each organ. From these data, it is suggested that peptide hydrolases in the brush border and the soluble fractions of small intestine are distinct enzymes and may play different roles in cellular function.
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Worwood M, Jacobs A. The subcellular distribution of orally administered 59Fe in rat small intestinal mucosa. Br J Haematol 1971; 20:587-97. [PMID: 5089949 DOI: 10.1111/j.1365-2141.1971.tb00797.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Connock MJ, Elkin A, Pover WF. The preparation of brush borders from the epithelial cells of the guineapig small intestine by zonal centrifugation. THE HISTOCHEMICAL JOURNAL 1971; 3:11-22. [PMID: 4329282 DOI: 10.1007/bf01686502] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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23
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Gardner JD, Brown MS, Laster L. The columnar epithelial cell of the small intestine: digestion and transport. 3. N Engl J Med 1970; 283:1317-24. [PMID: 4920694 DOI: 10.1056/nejm197012102832405] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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24
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Peters TJ. The subcellular localization of di- and tri-peptide hydrolase activity in guinea-pig small intestine. Biochem J 1970; 120:195-203. [PMID: 5494224 PMCID: PMC1179584 DOI: 10.1042/bj1200195] [Citation(s) in RCA: 84] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
1. Two different subcellular fractionation techniques were applied to guinea-pig intestinal mucosa and the composition of the brush borders prepared by the two methods were compared. 2. By using a kinetic assay system the subcellular distribution of activity against ten dipeptides and five tripeptides was studied. 3. Only small amounts (5-10%) of activity against dipeptides were found in the brush-border region, the enzymes being concentrated in the cytosol. 4. Significant amounts (10-60%) of activity against tripeptides were found in the brush border with the remainder largely present in the soluble fraction. 5. The relevance of these studies to the localization in vivo and the possible role of peptidases in protein digestion is discussed.
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25
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Grosse G, Neuhaus GA. [Aminopeptidase activity in urine in patients with sedative poisoning and under conditions of vita reducta]. KLINISCHE WOCHENSCHRIFT 1970; 48:978-85. [PMID: 5519413 DOI: 10.1007/bf01484401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Heizer WD, Laster L. Hydrolases in the mucosa of rat small intestine for phenylalanine-containing dipeptides. BIOCHIMICA ET BIOPHYSICA ACTA 1969; 185:409-23. [PMID: 5808704 DOI: 10.1016/0005-2744(69)90434-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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29
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Millington PF, Tovell PW. Quantitative changes in alkaline phosphatase in epithelial cells of rat small intestine from birth to weaning. THE HISTOCHEMICAL JOURNAL 1969; 1:311-21. [PMID: 5407471 DOI: 10.1007/bf01003277] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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31
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Penttilä A, Gripenberg J. Fine structure and enzyme histochemistry of developing duodenal epithelium of the chicken. ZEITSCHRIFT FUR ANATOMIE UND ENTWICKLUNGSGESCHICHTE 1969; 129:109-27. [PMID: 4311298 DOI: 10.1007/bf00522241] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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32
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Craft IL, Geddes D, Hyde CW, Wise IJ, Matthews DM. Absorption and malabsorption of glycine and glycine peptides in man. Gut 1968; 9:425-37. [PMID: 5677277 PMCID: PMC1552714 DOI: 10.1136/gut.9.4.425] [Citation(s) in RCA: 112] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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33
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Hugon J, Borgers M. Fine structural localization of acid and alkaline phosphatase activities in the absorbing cells of the duodenum of rodents. HISTOCHEMIE. HISTOCHEMISTRY. HISTOCHIMIE 1968; 12:42-66. [PMID: 5658762 DOI: 10.1007/bf00306346] [Citation(s) in RCA: 75] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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34
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Rhodes JB, Eichholz A, Crane RK. Studies on the organization of the brush border in intestinal epithelial cells. IV. Aminopeptidase activity in microvillus membranes of hamster intestinal brush borders. BIOCHIMICA ET BIOPHYSICA ACTA 1967; 135:959-65. [PMID: 4965166 DOI: 10.1016/0005-2736(67)90065-x] [Citation(s) in RCA: 75] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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35
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Clark B, Sherratt H. Glycolysis and oxidations in preparations from small-intestinal mucosa of four species. ACTA ACUST UNITED AC 1967. [DOI: 10.1016/0010-406x(67)90737-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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36
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Josefsson L, Sjöström H. Intestinal dipeptidases. IV. Studies on the release and subcellular distribution of intestinal dipeptidases of the mucosa cells of the pig. ACTA PHYSIOLOGICA SCANDINAVICA 1966; 67:27-33. [PMID: 5963299 DOI: 10.1111/j.1748-1716.1966.tb03283.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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37
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Brindley DN, Hübscher G. The intracellular distribution of the enzymes catalysing the biosynthesis of glycerides in the intestinal mucosa. BIOCHIMICA ET BIOPHYSICA ACTA 1965; 106:495-509. [PMID: 4286603 DOI: 10.1016/0005-2760(65)90066-4] [Citation(s) in RCA: 77] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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38
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Hübscher G, West GR, Brindley DN. Studies on the fractionation of mucosal homogenates from the small intestine. Biochem J 1965; 97:629-42. [PMID: 4286674 PMCID: PMC1264739 DOI: 10.1042/bj0970629] [Citation(s) in RCA: 202] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
1. Homogenates of the mucosa of the small intestine of the guinea pig were separated by fractional sedimentation into seven different fractions. The enzymic properties of some of these subcellular fractions were compared with those obtained from the mucosa of the small intestine of the rabbit and cat. 2. The enzymic properties of the low-speed sediment (15000g-min.) were investigated and it was shown that invertase and alkaline ribonuclease were predominantly located in this subcellular fraction, whereas alkaline phosphatase, aryl-amidase, acid phosphatase, acid ribonuclease and phosphoprotein phosphatase, though true constituents of this fraction, occurred to varying degrees in other subcellular structures also. 3. It was shown that the most probable source of the enzymic activities observed in the low-speed sediment was the brush border. Electron micrographs of the purified brush-border fraction indicated vesicles derived from the brush-border membrane. 4. A method is described for the fractionation of mucosal homogenates into a brush border-plus-nuclei fraction, a mitochondrial fraction, a microsomal fraction and a particle-free supernatant. The fractions were shown to be relatively pure, as indicated by the distribution of invertase, DNA, succinate dehydrogenase, glucose 6-phosphatase and 6-phosphogluconate dehydrogenase. 5. Most of the activity of four lysosomal enzymes present in the nuclei-free homogenate was sedimented at 375000g-min., suggesting the occurrence of lysosomal particles in mucosal homogenates. 6. Further fractionation of the microsomal membranes into three fractions is described. The enzymic composition of the membrane fractions is given and discussed in relation to their structure as seen in electron micrographs.
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Clark B, Porteous JW. The isolation and properties of epithelial-cell "ghosts" from rat small intestine. Biochem J 1965; 96:539-51. [PMID: 4220968 PMCID: PMC1207073 DOI: 10.1042/bj0960539] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
1. The preparation of gram quantities of isolated epithelial-cell ;ghosts' from mucosal scrapings of rat small intestine is described. The method involves dispersing the tissue by gentle homogenization in 6% dextran in Krebs-Ringer phosphate, pH7.4, followed by filtration through nylon cloth and sedimentation by low-speed centrifuging. 2. The isolated epithelial-cell ;ghosts' contained all of the DNA, but only 52% of the protein and 53-57% of the RNA of the original homogenate. They contained most of the activity of the following enzymes found in the homogenate: aminopeptidase (71%); alkaline beta-glycerophosphatase (82%); invertase (92%); adenosine triphosphatase (93-116%); acid beta-glycerophosphatase (83%); nonspecific esterase (76%); succinate dehydrogenase (96%). Only small proportions of the total lactate-dehydrogenase (10%) and phosphoglucose-isomerase (2%) activities found in the homogenate were recovered in the isolated cell ;ghosts'. 3. The epithelial-cell ;ghost' preparation did not respire unless cofactors and substrates were added, and did not consume glucose or produce lactic acid from glucose. 4. The effect of varying the composition of the homogenization medium was studied. Concentrations of dextran (mol.wt. 15x10(4)) from 1 to 12%, solutions of dextrans (all at 6%) with mol.wt. varying between 3.6x10(4) and 2x10(6), and a solution of 8% polyethylene glycol (mol.wt. 4000) served equally well for the production of epithelial-cell ;ghosts'. Two of these solutions, however, 12% dextran (mol.wt.15x10(4)) and 6% dextran (mol.wt. 2x10(6)), were too viscous to allow the complete sedimentation of the cell ;ghosts' at low relative centrifugal forces. Omission of either Krebs-Ringer phosphate or dextran from the medium resulted in almost complete cell breakage during the homogenization. 5. The isolated cell ;ghosts' were used as a starting material for subcellular fractionation of rat intestinal mucosa by differential centrifugation. The distributions of protein and succinate-dehydrogenase activity among the fractions were compared with corresponding values in fractions isolated by differential centrifugation of mucosa homogenized in 0.3m-sucrose-5mm-EDTA, pH7.4. The method in which cell ;ghosts' were used as starting material gave a better separation and cleaner fractions than the method in which untreated mucosal scrapings were used.
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