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:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A method for measuring brush border membrane enzymes from small intestinal biopsies by crossed immunoelectrophoresis is presented. The use of a brush border specific antiserum made isolation of the brush border membrane before analysis unnecessary. This prevented loss of material which, together with inactivation of enzymes, was a limiting factor in previous studies of brush border enzymes from peroral biopsies. In 58 biopsies from patients without gastrointestinal disorders a close correlation between antigenic activity and corresponding enzymatic activity was shown for the following enzymes: sucrase-isomaltase (EC 3.2.1.48-EC 3.2.1.10), lactase-phlorizin hydrolase (EC 3.2.1.23-EC 3.2.1.62), microvillus aminopeptidase (microsomal, EC 3.4.11.2) and dipeptidyl peptidase IV (EC 3.4.14.X). The immunoelectrophoretic patterns of intestinal mucosa near the ligament of Treitz, and in jejunum and ileum were established. The method presented is thought to be of value in further studies of the molecular basis of brush border diseases.
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PMID:Immunoelectrophoretic studies on human small intestinal brush border proteins. A quantitative study of brush border enzymes from single small intestinal biopsies. 10 36

Several classes of proteolytic enzymes were used to gain an insight into the biochemical composition of the antiotensin II (ATII) receptor prepared from bovine adrenal cortices. Exposure of the receptor fractions to trypsin reduced their capacity to bind [3H]ATII. Phospholipases A2 and C similarly inhibited the [3H]ATII binding process, while phospholipase D had no effect. Binding was stimulated following addition of phosphatidylcholine but inhibited by lysophosphatidylcholine. Neuraminidase had no influence on [3H]ATII affinity for binding, while beta-galactosidase reduced binding of the radioligand. Concanavalin A did not displace [3H]ATII bound to receptor fractions. Very little aminopeptidase activity was detected in the receptor fraction, relative to the homogenate. The data suggest that the ATII recognition sites contain protein moieties, while phospholipids may play an essential role in ATII binding. Galactose units may form a part of the ATII receptor not directly associated with the binding site. The peptidase studies indicate that ATII probably cannot be hydrolyzed to its des-Asp1 metabolite at or near the site of binding.
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PMID:Enzymatic modifications of bovine adrenocortical angiotensin II receptors. 22 26

A brush-border-specific antiserum was raised in rabbits, with Triton X-100-solubilized brush border proteins from pig intestine being used as antigens. The antiserum was used in immunoelectrophoretic studies of brush border proteins solubilized with Triton X-100. Five immunoprecipitates were obtained which corresponded to microsomal aminopeptidase (EC 3.4.11.2), asparate aminopeptidase (EC 3.4.11.7), lactase (beta-galactosidase, EC 3.2.1.23), maltase (exo-1,4-alpha-glucosidase, EC 3.2.1.3) and sucrase-isomaltase (sucrose alpha-glucohydrolase, EC 3.2.1.48). A faint immunoprecipitate was also found for the glycylprolyl dipeptidyl peptidase (EC 3.4.14.-). The brush border proteins were solubilized on a large scale from a brush border membrane preparation by the use of Triton X-100; the peptidases obtained were homogeneous in size and had hydrophobic properties. By chromatography on columns of concanavalin A-Sepharose, hydroxyapatite, Ultrogel AcA 34, DEAE-cellulose and immunosorbent, gamma-glutamyl transpeptidase (gamma-glutamyl transferase, EC 2.3.2.2) and microsomal aminopeptidase were each isolated in separate fractions. Glycylprolyl dipeptidyl peptidase and asparate aminopeptidase were obtained in another fraction. Immunoelectrophoretic, inhibitor and chromatographic studies showed that the intestinal brush border peptidases are similar to the corresponding particulate peptidases obtained from other organs.
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PMID:Intestinal brush border peptidases. 24 83

The subcellular localization of aminopeptidase N (previously called aminoendopeptidase) has been investigated. This enzyme was found to be partially released (30-40%) by osmotic shock or by converting Escherichia coli K10 cells to spheroplasts. However, in all other E. coli strains (K12, B/r, MRE 600, ML 308) tested, this enzyme is not released at all by these procedures and thus behaves like a cytoplasmic enzyme. The crypticity of aminopeptidase N is surprisingly low, 75-85% of the enzyme activity is directly assayable in intact cells of any E. coli strain. Various inhibitors of transport systems do not interfer with this assay. Aminopeptidase activity could also be assayed in spheroplasts, even when an insolubilized substrate was used, which suggests a surface location of this enzyme. As well, N-ethylmaleimide (0.4 mM), under conditions which do not allow penetration in the cytoplasm, caused 70% inhibition of aminopeptidase N. Binding of 125I-labeled antiaminopeptidase N antibody to spheroplasts (from K12 strain) was used to assay the orientation of aminopeptidase N in the membrane. This enzyme is exposed on the outer surface of the cytoplasmic membrane. Confirmation of this orientation was obtained by comparing the accessibility of aminopeptidase, alkaline phosphatase and beta-galactosidase to fluorescamine in intact cells. Only 16% of the total beta-galactosidase was labeled with this fluorescent reagent whereas 44-45% of the aminopeptidase N and 59% of the alkaline phosphatase were labeled. Electron microscopic visualization of insolubilized reaction products of aminopeptidase N within the cells showed that these products are located at the poles of the cells. Neither mutant cells which were devoid of aminopeptidase N activity nor parental strains with the enzyme activity inhibited with phenylmercuric chloride contained the characteristic black caps. Thus, it appears that the periplasm is enlarged at the poles of the cells and that the reaction product is mainly located in these places. Investigation of the type of interactions of aminopeptidase N with the plasma membrane only revealed that aminopeptidase N has mainly an electrostatic interaction with the outer surface, probably mediated by magnesium ion bridges. Additional interactions are involved since disruption of the integrity of the cytoplasmic membrane is required to totally release this enzyme.
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PMID:Aminopeptidase N from Escherichia coli. Unusual interactions with the cell surface. 32 10

An endoproteolytic enzyme of Escherichia coli, designated protease III, has been purified about 9,600-fold to homogeneity with a 6% yield. The purified enzyme consists of a single polypeptide chain of Mr 110,000 and is most active at pH 7.4. Protease III is very sensitive to metal-chelating agents and reducing agents. The EDTA-inactivated enzyme can be reactivated by Zn2+, Co2+ or Mn2+. Protease III is devoid of activity toward aminopeptidase, carboxypeptidase, or esterase substrates but rapidly degrades small proteins. When fragments of beta-galactosidase are used as substrates for protease III, the enzyme preferentially degrades proteins with molecular weights of less than 7,000. Protease III cleaves the oxidized insulin B chain at two sites with an initial rapid cleavage at Tyr-Leu (16-17) and a second slower cut at Phe-Tyr (25-26).
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PMID:Purification and characterization of protease III from Escherichia coli. 37 13

We initiated a genetic reversion analysis at the HIS4 locus to identify components of the translation initiation complex that are important for ribosomal recognition of an initiator codon. Three unlinked suppressor loci, suil, sui2, and SUI3, that restore expression of both HIS4 and HIS4-lacZ in the absence of an AUG initiator codon were identified. In previous studies, it was demonstrated that the sui2 and SUI3 genes encode mutated forms of the alpha and beta subunits, respectively, of eukaryotic translation initiation factor 2 (eIF-2). In this report, we describe the molecular and biochemical characterizations of the sui1 suppressor locus. The DNA sequence of the SUI1+ gene shows that it encodes a protein of 108 amino acids with a calculated Mr of 12,300. The sui1 suppressor genes all contain single base pair changes that alter a single amino acid within this 108-amino-acid sequence. sui1 suppressor strains that are temperature sensitive for growth on enriched medium have altered polysome profiles at the restrictive temperature typical of those caused by alteration of a protein that functions during the translation initiation process. Gene disruption experiments showed that the SUI1+ gene encodes an essential protein, and antibodies directed against the SUI1+ coding region identified a protein with the predicted Mr in a ribosomal salt wash fraction. As observed for sui2 and SUI3 suppression events, protein sequence analysis of His4-beta-galactosidase fusion proteins produced by sui1 suppression events indicated that a UUG codon is used as the site of translation initiation in the absence of an AUG start codon in HIS4. Changing the penultimate proline codon 3' to UUG at his4 to a Phe codon (UUC) blocks aminopeptidase cleavage of the amino-terminal amino acid of the His4-beta-galactosidase protein, as noted by the appearance of Met in the first cycle of the Edman degradation reaction. The appearance of Met in the first cycle, as noted, in either a sui1 or a SUI3 suppressor strain showed that the mechanism of suppression is the same for both suppressor genes and allows the initiator tRNA to mismatch base pair with the UUG codon. This suggests that the Sui1 gene product performs a function similar to that of the beta subunit of eIF-2 as encoded by the SUI3 gene. However, the Sui1 gene product does not appear to be a required subunit of eIF-2 on the basis of purification schemes designed to identify the GTP-dependent binding activity of eIF-2 for the initiator tRNA. In addition, suppressor mutations in the sui1 gene, in contrast to suppressor mutations in the sui2 or SUI3 gene, do not alter the GTP-dependent binding activity of the eIF-2. The simplest interpretation of these studies is that the sui1 suppressor gene defines an additional factor that functions in concert with eIF-2 to enable tRNAiMet to establish ribosomal recognition of an AUG initiator codon.
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PMID:The suil suppressor locus in Saccharomyces cerevisiae encodes a translation factor that functions during tRNA(iMet) recognition of the start codon. 172 2

Eight of 22 non-capsulate strains of Neisseria meningitidis previously isolated from primary school children were re-identified as N. polysaccharea by aminopeptidase reactions and polysaccharide production. N. polysaccharea was not identified amongst 91 non-capsulate strains of N. meningitidis isolated from adults attending the Genito-urinary Medicine clinic, Westminster Hospital, London. The biochemical reactions of N. polysaccharea strains were similar to those of N. lactamica and N. gonorrhoeae, but N. polysaccharea could be distinguished from these organisms by examination of beta-galactosidase activity, carbohydrate reactions and polysaccharide production. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed closer similarity of N. polysaccharea to N. lactamica than to the pathogenic Neisseria spp. An additional finding was variation in the position of one of the major proteins of N. lactamica in the 34-39-Kda region.
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PMID:The phenotypic relationship of Neisseria polysaccharea to commensal and pathogenic Neisseria spp. 250 17

Different enzymatic activities were studied in the human pancreatic cancer cell line CAPAN-1 in order to analyze their relation to differentiation. Alkaline phosphatase (Alk Ph), acid phosphatase, aminopeptidase, dipeptidyl peptidase IV, acid and neutral alpha-glucosidases, and acid beta-galactosidase were present. Especially alkaline phosphatase, which we have found to be of the placental type isoenzyme, is being highly expressed. Spontaneous cell differentiation at confluence as well as differentiating agents: sodium butyrate and DMSO, modulated the levels of three enzymes: Alk. Ph., aminopeptidase, and acid alpha-glucosidase. The exposure of the cells to the differentiating agents amplified the modulations occurring during the spontaneous differentiation. Aminopeptidase and acid alpha-glucosidase were found to be induced by differentiation. Alk Ph specific activity was significantly increased by the spontaneous and the butyrate-induced differentiations; whereas DMSO exerted an opposite effect, probably related to its biphasic action on cell proliferation.
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PMID:Modulation of enzymatic activities during spontaneous and induced differentiation in a human pancreatic adenocarcinoma cell line CAPAN-1. 254 14

In a significant fraction of the Escherichia coli cytosolic proteins, the N-terminal methionine residue incorporated during the translation initiation step is excised. The N-terminal methionine excision is catalyzed by methionyl-aminopeptidase (MAP). Previous studies have suggested that the action of this enzyme could depend mainly on the nature of the second amino acid residue in the polypeptide chain. In this study, to achieve a systematic analysis of the specificity of MAP action, each of the 20 amino acids was introduced at the penultimate position of methionyl-tRNA synthetase of E. coli and the extent of in vivo methionine excision was measured. To facilitate variant protein purification and N-terminal sequence determination, an expression shuttle vector based on protein fusion with beta-galactosidase was used. From our results, methionine excision catalyzed by MAP is shown to obey the following rule: the catalytic efficiency of MAP, and therefore the extent of cleavage, decreases in parallel with the increasing of the maximal side-chain length of the amino acid in the penultimate position. This molecular model accounts for the rate of N-terminal methionine excision in E. coli, as deduced from the analysis of 100 protein N-terminal sequences.
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PMID:Extent of N-terminal methionine excision from Escherichia coli proteins is governed by the side-chain length of the penultimate amino acid. 268 40

To evaluate the response of the small intestinal mucosa to Saccharomyces boulardii (S.b.), a yeast widely used in some countries as an adjuvant drug with oral antimicrobial therapy, seven healthy adult volunteers were treated with high doses of lyophilized S.b. (250 mg four times per day) for 2 wk. A peroral jejunal suction biopsy was performed on days 0 and 15 of the study. Compared to the initial biopsy, histological examination of the posttrial biopsy revealed no morphological alteration nor change in villus height or crypt depth. After treatment, the specific activity (per U protein) of sucrase, lactase, and maltase was, respectively, increased by 82% (p less than 0.05) 77% (p less than 0.05), and 75% (p less than 0.05) over the basal activity of the enzymes measured on day 0, whereas mucosal protein content remained unchanged. Similar findings were found in the jejunum of adult rats treated for 5 days with either viable or killed S.b. cells. The changes in total enzyme activity (per jejunal segment) paralleled the changes in specific enzyme activity. In vitro assays on freshly prepared suspensions of S.b. (6.0 X 10(8) viable cells/ml) evidenced a high activity for sucrase (mean +/- SE: 8 364 +/- 1280 U X g X protein-1) but no maltase, neutral lactase, acid beta-galactosidase, or aminopeptidase activity. To determine whether treatment with S.b. could influence the incorporation rate of neutral lactase into the brush border membrane, 14-day-old sucklings treated either with saline or with S.b. were given intraperitoneally a dose of 20 microCi D-[1(14)C] glucosamine 3 hours before sacrifice.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Response of human and rat small intestinal mucosa to oral administration of Saccharomyces boulardii. 308 Jul 30


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