The digestive function of the epithelium of the small intestine

Miller, David L.; Crane, Robert K.

doi:10.1016/0006-3002(61)90678-3

Cited by 363 publications

(46 citation statements)

References 13 publications

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“…The observation on the formation of small vesicles from the intact brush border by treatment in a Waring Blendor is at variance with the results of Miller & Crane (1961), who prepared brushborder fractions by using a Waring Blendor for homogenization, but is in agreement with the results of Carnie & Porteous (1962b). These authors reported that, depending on the type of homogenizer Vol.…”

Section: Discussionsupporting

confidence: 72%

“…To demonstrate this point the reports on invertase, alkaline phosphatase and 'leucine aminopeptidase' may be discussed. Miller & Crane (1961) and Holt & Miller (1962) were the first to report that, in the epithelial layer of the small-intestinal mucosa of the hamster, invertase is a brush-border enzyme. A similar intracellular distribution of invertase was reported for the small-intestinal mucosa of the rabbit (Carnie & Porteous, 1962b;Gitzelmann, Davidson & Osinchak, 1964).…”

Section: Discussionmentioning

confidence: 99%

“…Miller & Crane (1961) described a method for the isolation of a brush-border fraction from the intestinal mucosa of the hamster by using a strongly hypoosmotic medium, but no conclusions can be drawn about the sedimentation properties of this structure in iso-osmotic media with a higher density. Finally, the microsomal fraction obtained by conventional fractionation procedures is a mixture of several subcellular structures such as the smooth-surface membranes of the Golgi apparatus, the roughsurface membranes of the endoplasmic reticulum and possibly fragments of the cell wall.…”

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confidence: 99%

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Studies on the fractionation of mucosal homogenates from the small intestine

Hübscher¹,

West²,

Brindley³

1966

Biochemical Journal

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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 (150OOg-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 ofthe 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 supematant. 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 3750OOg-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.The fractionation of homogenates of the mucosa of the small intestine has been described for preparations from the rat (Schmidt,

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Section: Discussionsupporting

confidence: 72%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Studies on the fractionation of mucosal homogenates from the small intestine

Hübscher¹,

West²,

Brindley³

1966

Biochemical Journal

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“…Maltase (a-D-glucoside glucohydrolase, EC 3.2.1.20)/glucoamylase (1,4-a-D-glucan glucohydrolase, EC 3.2.1.3) is one of a group of oligo-and disaccharidases which are constituents of the intestinal brush-border membrane (Miller & Crane, 1961;Dahlqvist & Thomson, 1963;Eichholz & Crane, 1965;Forstner et al, 1968;Alpers -& Solin, 1970). These carbohydrases are easily solubilized from the membrane in good yield by papain digestion (Auricchio et al, 1963;Eichholz, 1968;Forstner, 1971) and thus their purification is greatly facilitated (Cogoli et atl., 1972).…”

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confidence: 99%

Purification of rat intestinal maltase/glucoamylase and its anomalous dissociation either by heat or by low pH

Flanagan¹,

Forstner²

1978

Biochemical Journal

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Maltase-glucoamylase, a microvillous membrane ectoenzyme, was solubilized from rat intestinal mucosa by digestion with papain and subsequently purified to homogeneity with an overall yield of 10–20%. An antibody to the purified enzyme formed a single precipitin line in immunodiffusion experiments with an intestinal homogenate. The enzyme was shown to be an acidic glycoprotein (20% sugar by weight) which contained low amounts of cysteine and no sialic acid. At pH3–6, maltase activity was slowly lost, but the enzyme was re-activated by re-adjustment of the pH to neutrality. However, in the presence of sodium dodecyl sulphate, acid pH values inactivated maltase irreversibly, and at the same time converted the enzyme (mol.wt. 500000 approx.) into five new species with apparent molecular weights ranging from 134000 to 480000 as judged by polyacrylamide-gel electrophoresis. The same five fragments were also formed by boiling the enzyme for brief periods in the presence of sodium dodecyl sulphate or urea either with or without reducing agents. The dissociated species were stable on re-electrophoresis, and amino acid analysis showed them to be very similar to each other and to the original enzyme. The bands migrated anomalously on polyacrylamide gels of different concentration, thereby preventing the assignment of precise molecular weights. It is possible that the five species may represent stable aggregates of a common monomer of the enzyme.

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“…A characterization of the biochemical properties of the isolated brush border, therefore, should provide significant information on the molecular mechanisms underlying tubular reabsorption . Brush borders from intestinal epithelial cells have been isolated as a discrete subcellular fraction, and several enzymes are now known to be associated with this membranous structure (1)(2)(3)(4) . In contrast, little has been done on the isolation or biochemical characterization of the renal brush border .…”

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confidence: 99%

Isolation and Biochemical Characterization of Brush Borders From Rabbit Kidney

Berger

Sacktor

1970

The Journal of Cell Biology

152

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A technique for the isolation of intact brush borders from rabbit renal cortex was evaluated . The procedure was monitored by phase and electron microscopy and marker enzymes, i .e . ATP :NMN adenylyl transferase, nuclear ; cytochrome oxidase, mitochondrial ; (3-glucuronidase, lysosomal ; and glucose-6-Pase, microsomal ; and indicated an essentially pure preparation of brush borders . The disaccharidase, trehalase, previously reported in renal tubules, was localized uniquely in brush borders . Maltase was also found ; the specific activities of the two enzymes in the brush borders were increased 10-to 20-fold . Other disaccharidases, such as sucrase, isomaltase, lactase, and cellobiase, were absent . It is suggested that trehalase and maltase are appropriate candidates for marker enzymes of the renal brush border. Isolated brush borders possessed a ouabain-sensitive (Na+ + K+) ATPase, an oligomycin-insensitive Mg++ ATPase, and a Ca++-activated ATPase . Alkaline phosphatases, dephosphorylating (3-glycero-P, and trehalose-6-P were also present . The specific activities of these enzymes were increased three-to-five fold in the brush-border preparations ; however, activities were found in other subcellular fractions of the renal cortex . Hexokinase, although evident in the isolated brush border, was found prominently associated with other membranous fractions . Phosphoglucomutase and UDPG pyrophosphorylase were localized in the soluble fraction of the renal cortex .The renal brush border has a prominent role in determining the specificity and rate of reabsorption from the glomerular filtrate . A characterization of the biochemical properties of the isolated brush border, therefore, should provide significant information on the molecular mechanisms underlying tubular reabsorption . Brush borders from intestinal epithelial cells have been isolated as a discrete subcellular fraction, and several enzymes are now known to be associated with this membranous structure (1-4) . In contrast, little has been done on the isolation or biochemical characterization of the renal brush border . Recently, however, Thuneberg and Rostgaard (5) described a procedure for isolating brush borders from rabbit kidney cortex, but no biochemical correlates were made, and Kinne and Kinne-Saffran (6) and

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The digestive function of the epithelium of the small intestine

Cited by 363 publications

References 13 publications

Studies on the fractionation of mucosal homogenates from the small intestine

Studies on the fractionation of mucosal homogenates from the small intestine

Purification of rat intestinal maltase/glucoamylase and its anomalous dissociation either by heat or by low pH

Isolation and Biochemical Characterization of Brush Borders From Rabbit Kidney

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