The Experts below are selected from a list of 3300 Experts worldwide ranked by ideXlab platform
Oswaldo Hernandezhernandez - One of the best experts on this subject based on the ideXlab platform.
-
hydrolysis and transglycosylation activities of glycosidases from small Intestine Brush Border membrane vesicles
Food Research International, 2021Co-Authors: Lesbia Cristina Juliogonzalez, Javier F Moreno, Maria Luisa Jimeno, Elisa G Doyaguez, Agustin Olano, Nieves Corzo, Oswaldo HernandezhernandezAbstract:Abstract In order to know the catalytic activities of the disaccharidases expressed in the mammalian small intestinal Brush-Border membrane vesicles (BBMV) high concentrated solutions of sucrose, maltose, isomaltulose, trehalose and the mixture sucrose:lactose were incubated with pig small Intestine disaccharidases. The hydrolysis and transglycosylation reactions generated new di- and trisaccharides, characterized and quantified by GC–MS and NMR, except for trehalose where only hydrolysis was detected. In general, α-glucosyl-glucoses and α-glucosyl-fructoses were the most abundant structures, whereas no fructosyl-fructoses or fructosyl-glucoses were found. The in-depth structural characterization of the obtained carbohydrates represents a new alternative to understand the potential catalytic activities of pig small intestinal disaccharidases. The hypothesis that the oligosaccharides synthesized by glycoside hydrolases could be also hydrolysed by the same enzymes was confirmed. This information could be extremely useful in the design of new non-digestible or partially digestible oligosaccharides with potential prebiotic properties.
David E. Ong - One of the best experts on this subject based on the ideXlab platform.
-
Specificity of the retinol transporter of the rat small Intestine Brush Border.
Biochemistry, 1994Co-Authors: Stephanie E. Dew, David E. OngAbstract:The uptake of vitamin A (all-trans-retinol) by the absorptive cell of the small Intestine is the necessary first step in its utilization by the organism and appears to involve a specific carrier that operates by facilitated diffusion. We investigated the specificity of that process by determining the absorption of all-trans-, 13-cis-, and 9-cis-retinol, 3-dehydroretinol, and retinal (vitamin A aldehyde) by gut sheets from the small Intestine of suckling rats. We found that radiolabeled all-trans-retinol and 3-dehydroretinol were absorbed at similar rates and that approximately 60% of the total absorption could be competed for by unlabeled all-trans-retinol. A similar level of inhibition could be achieved for all-trans-retinol absorption by treating the intestinal sheets with N-ethylmaleimide. The noncompetable, noninhibitable component of all-trans-retinol absorption corresponded to the total absorption rate for 13-cis- and 9-cis-retinol and retinal. Additionally, we found that the relative rates of transport of these retinoids were unrelated to their relative affinities for the abundant absorptive cell retinoid carrier protein, cellular retinol-binding protein, type II, and were not driven by esterification. This confirms that the absorption of retinol is facilitated by a transporter and establishes that it is specific for the all-trans alcohol forms of vitamin A.
Pierre Ripoche - One of the best experts on this subject based on the ideXlab platform.
-
mechanisms of zinc transport into pig small Intestine Brush Border membrane vesicles
The Journal of Physiology, 1993Co-Authors: F Tacnet, F Lauthier, Pierre RipocheAbstract:1. The purpose of the present work was to examine certain membrane transport mechanisms likely to carry zinc across the Brush-Border membrane of pig small Intestine, isolated in a vesicular form. 2. In initial velocity conditions, saturation kinetics revealed a great effect of pH on zinc transport: optimal conditions were observed with an intravesicular pH of around 6.6 with or without a H+ gradient; however, this did not allow us to conclude the existence of a neutral exchange between Zn2+ and H+ ions. 3. By measuring 36Cl uptakes, the presence of the Cl(-)-HCO3- or Cl(-)-OH-antiporter with typical 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) sensitivity was detected in vesicles; zinc did not alter this anionic exchange activity. A 65Zn time course, performed in conditions identical with those for 36Cl uptake, was DIDS insensitive and was greatly inhibited by an outward OH- gradient. This could argue against a transport of zinc as a complex with Cl- and HCO3- through the anion antiporter. 4. When external Cl- and HCO3- were replaced by SCN-, able to form a Zn(SCN)4(2-) complex, we observed a stimulating effect of outward HCO3- gradients on 65Zn uptake but neither DIDS nor diphenylamine-2-carboxylate (DPC) inhibited the transport in these conditions. This suggested that the intestinal anion antiporter was not a major route for zinc reabsorption. 5. The tripeptide Gly-Gly-His at low concentrations stimulated 65Zn uptake, then inhibited it in a dose-dependent manner either in the presence of an inward H+ gradient or in the presence of a membrane potential 'negative inside' or in both situations. These conditions are necessary for the active transport of the peptide and this strongly suggests that zinc can be transported as a [Gly-Gly-His-Zn] complex, utilizing the peptide carrier system.
Bruce D Uhal - One of the best experts on this subject based on the ideXlab platform.
-
degradation of the protective lung enzyme angiotensin converting enzyme 2 ace 2 by human meconium a potential mechanism of meconium aspiration syndrome
Pediatrics, 2018Co-Authors: Chintan Gandhi, Ira H Gewolb, Bruce D UhalAbstract:Background: Meconium aspiration syndrome (MAS) is a significant problem in term and near-term neonates. Meconium has been shown to induce apoptotic death of alveolar epithelial cells. It is known that meconium contains pancreatic and Intestine Brush Border enzymes which might be responsible for acute lung damage observed in MAS. Previous studies from our lab showed that ACE-2 is downregulated in experimental lung fibrosis. The main function of ACE-2 is to convert the octapeptide ANG II to the heptapeptide ANG 1-7. ANG II is a …
Lesbia Cristina Juliogonzalez - One of the best experts on this subject based on the ideXlab platform.
-
hydrolysis and transglycosylation activities of glycosidases from small Intestine Brush Border membrane vesicles
Food Research International, 2021Co-Authors: Lesbia Cristina Juliogonzalez, Javier F Moreno, Maria Luisa Jimeno, Elisa G Doyaguez, Agustin Olano, Nieves Corzo, Oswaldo HernandezhernandezAbstract:Abstract In order to know the catalytic activities of the disaccharidases expressed in the mammalian small intestinal Brush-Border membrane vesicles (BBMV) high concentrated solutions of sucrose, maltose, isomaltulose, trehalose and the mixture sucrose:lactose were incubated with pig small Intestine disaccharidases. The hydrolysis and transglycosylation reactions generated new di- and trisaccharides, characterized and quantified by GC–MS and NMR, except for trehalose where only hydrolysis was detected. In general, α-glucosyl-glucoses and α-glucosyl-fructoses were the most abundant structures, whereas no fructosyl-fructoses or fructosyl-glucoses were found. The in-depth structural characterization of the obtained carbohydrates represents a new alternative to understand the potential catalytic activities of pig small intestinal disaccharidases. The hypothesis that the oligosaccharides synthesized by glycoside hydrolases could be also hydrolysed by the same enzymes was confirmed. This information could be extremely useful in the design of new non-digestible or partially digestible oligosaccharides with potential prebiotic properties.
