Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.20 (alpha-glucosidase)
 4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Analytical subcellular fractionation of tissue whole homogenates and microanalysis of organelle marker enzymes were used to study the activity and subcellular localization of enzymes implicated in HCO3 secretion in rat duodenal and gastric antral mucosae. The following organelles, characterized by their marker enzymes, were located in the density gradients: cytosol (lactate dehydrogenase), plasma membrane (5'-nucleotidase), peroxisomes (catalase), mitochondria (succinate dehydrogenase), endoplasmic reticulum (Tris-resistant alpha-glucosidase), lysosomes (N-beta-acetylglucosaminidase), and brush-border membrane (Zn2+-resistant alpha-glucosidase and alkaline phosphatase). Compared with gastric antrum, rat duodenal mucosa contained over twice the activity of HCO3-ATPase and of Na+-K+-ATPase but less than one-tenth the activity of carbonic anhydrase. Duodenal HCO3-ATPase activity was observed in both mitochondrial and brush-border membrane fractions, whereas antral HCO3-ATPase activity was confined to mitochondria. Na+-K+-ATPase activity was found largely in the basolateral membrane (duodenum) and plasma membrane (antrum). In both tissues carbonic anhydrase activity was localized to the cytosolic fraction. These observations offer further evidence that differing biochemical mechanisms underlie HCO3 secretion by gastric and duodenal epithelia.
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PMID:Activities and subcellular localizations of enzymes implicated in gastroduodenal bicarbonate secretion. 608 73

Heating of several protein solutions at 40-47 degrees C for 5-60 min in the presence of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) liposomes induced the translocation of beta-galactosidase (beta-gal), alpha-glucosidase (alpha-glu) and bovine carbonic anhydrase (CAB) from outer to inner aqueous phase across the liposome membrane. The translocated amounts of beta-gal at various temperatures were maximized under suitable heating conditions (45 degrees C, 30 min). Those of alpha-glu and CAB were maximized at 40-45 and 60 degrees C, respectively. Each maximum value could be correlated with the corresponding local hydrophobicity of each protein evaluated by the aqueous two-phase partitioning method. The possibility to apply these heat-induced translocation phenomena to the bioseparation of proteins was successfully demonstrated for the model mixture solution of beta-gal, alpha-glu and CAB.
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PMID:Selective separation process of proteins based on the heat stress-induced translocation across phospholipid membranes. 969 80

The possibility of the stimuli-responsive separation of proteins was investigated using immobilized liposome chromatography (ILC) as novel aqueous two-phase systems. The specific capacity factor (k(s)) of beta-galactosidase, obtained by analysis of ILC, was varied by changing the pH of the solution and was maximized at the specific pH of 5 (k(s),max = 5.57). The k(s) values were found to correspond well with their local hydrophobicities, which can be determined by the aqueous two-phase partitioning method. The variation of k(s), therefore, indicates a change in the surface properties of a protein during conformational change under pH stimuli. A similar phenomenon is observed in the case of other proteins (alpha-glucosidase, k(s),max = 11.3 at pH 4; carbonic anhydrase from bovine, k(s),max = 6.53 at pH 4). The difference in the height and/or the position of the peaks of the ks-pH curves of each protein suggests a difference in their pH denaturation in the ILC column. Based on these results, the mutual separation of the above proteins at pH 4 could be successfully performed by selecting their specific capacity factor as a design parameter.
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PMID:Stimuli-responsive separation of proteins using immobilized liposome chromatography. 1094 75

Nutrient digestion and absorption after blood feeding are important events for Lutzomyia longipalpis, which uses these nutrients to produce eggs. In this context, the pH inside the digestive tract is an important physiological feature as it can markedly influence the digestive process as well as interfere with Leishmania development in infected phlebotomines. It was described previously that unfed females have an acidic midgut (pH 6). In this study, the pH inside the midgut of blood-fed females was measured. The abdominal midgut (AM) pH varied from 8.15+/-0.31 in the first 10 h post-blood meal to 7.7+/-0.17 after 24 h. While the AM was alkaline during blood digestion, the pH in the thoracic midgut (TM) remained acidic (5.5-6.0). In agreement with these findings, the enzyme alpha-glucosidase, which has an optimum pH of 5.8, is mainly encountered in the acidic TM. The capacity of unfed females to maintain the acidic intestinal pH was also evaluated. Our results showed the presence of an efficient mechanism that maintains the pH almost constant at about 6 in the midgut, but not in the crop. This mechanism is promptly interrupted in the AM by blood ingestion. RT-PCR results indicated the presence of carbonic anhydrase in the midgut cells, which apparently is required to maintain the pH at 6 in the midgut of unfed females. Investigations on the phenomenon of alkalization observed after blood ingestion indicated that two mechanisms are involved: in addition to the alkalization promoted by CO2 volatilization there is a minor contribution from a second mechanism not yet characterized. Some inferences concerning Leishmania development and pH in the digestive tube are presented.
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PMID:The physiology of the midgut of Lutzomyia longipalpis (Lutz and Neiva 1912): pH in different physiological conditions and mechanisms involved in its control. 1872 37