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The Biochemical Journal Sep 1984The transport of maltose in Saccharomyces cerevisiae has been generally accepted as a H+-sugar symport, with a stoichiometrical ratio of 1:1. A simultaneous exit of K+...
The transport of maltose in Saccharomyces cerevisiae has been generally accepted as a H+-sugar symport, with a stoichiometrical ratio of 1:1. A simultaneous exit of K+ from the cells with the initial uptake of maltose has been reported previously. By using a K+-selective electrode and radioactive maltose, we were able to measure the exit of 1 mol of K+/mol of maltose taken up by the cells in the first 10-15 s. This stoichiometrical ratio is pH-independent. So, uptake of protons in a non-buffered cell suspension or exit of K+ in a buffered one can be used to measure initial rates of maltose uptake. We have used a K+ electrode and a pH electrode to study the effect of external pH and K+ respectively on the kinetic parameters of maltose transport. The following results were obtained: the apparent half-saturation constant for maltose (Km) increased from 5.2 mM at pH 5.8 to 38.0 mM at pH 7.8; the same increase in pH halved the apparent maximum uptake rate (Vmax); K+ had an inhibitory effect, decreasing Vmax. and increasing Km at pH values above 5; K+ had a stimulating effect at pH values below or equal to 4. Under physiological conditions, i.e. lower pH outside, neutral pH inside and much higher [K+] inside the cell, and assuming symmetry of the system, a higher affinity for maltose is to be expected in the outer face of the plasma membrane. This behaviour of the system could explain, by itself, the maintenance of the high concentration of free maltose inside the cell (necessary because of the low affinity of the maltase), without significant back transport to the outside.
Topics: Biological Transport; Hydrogen-Ion Concentration; Kinetics; Maltose; Potassium; Saccharomyces cerevisiae; Salts
PubMed: 6383358
DOI: 10.1042/bj2220293 -
Drug Design, Development and Therapy 2014With the challenge of optimizing iron delivery, new intravenous (iv) iron-carbohydrate complexes have been developed in the last few years. A good example of these new... (Review)
Review
With the challenge of optimizing iron delivery, new intravenous (iv) iron-carbohydrate complexes have been developed in the last few years. A good example of these new compounds is ferric carboxymaltose (FCM), which has recently been approved by the US Food and Drug Administration for the treatment of iron deficiency anemia in adult patients who are intolerant to oral iron or present an unsatisfactory response to oral iron, and in adult patients with non-dialysis-dependent chronic kidney disease (NDD-CKD). FCM is a robust and stable complex similar to ferritin, which minimizes the release of labile iron during administration, allowing higher doses to be administered in a single application and with a favorable cost-effective rate. Cumulative information from randomized, controlled, multicenter trials on a diverse range of indications, including patients with chronic heart failure, postpartum anemia/abnormal uterine bleeding, inflammatory bowel disease, NDD-CKD, and those undergoing hemodialysis, supports the efficacy of FCM for iron replacement in patients with iron deficiency and iron-deficiency anemia. Furthermore, as FCM is a dextran-free iron-carbohydrate complex (which has a very low risk for hypersensitivity reactions) with a small proportion of the reported adverse effects in a large number of subjects who received FCM, it may be considered a safe drug. Therefore, FCM appears as an interesting option to apply high doses of iron as a single infusion in a few minutes in order to obtain the quick replacement of iron stores. The present review on FCM summarizes diverse aspects such as pharmacology characteristics and analyzes trials on the efficacy/safety of FCM versus oral iron and different iv iron compounds in multiple clinical scenarios. Additionally, the information on cost effectiveness and data on change in quality of life are also discussed.
Topics: Anemia, Iron-Deficiency; Drug Delivery Systems; Ferric Compounds; Humans; Maltose
PubMed: 25525337
DOI: 10.2147/DDDT.S55499 -
International Journal of Molecular... Jul 2023Potassium humate is a widely used biostimulant known for its ability to enhance growth and improve tolerance to abiotic stress. However, the molecular mechanisms...
Potassium humate is a widely used biostimulant known for its ability to enhance growth and improve tolerance to abiotic stress. However, the molecular mechanisms explaining its effects remain poorly understood. In this study, we investigated the mechanism of action of potassium humate using the model plant . We demonstrated that a formulation of potassium humate effectively increased the fresh weight accumulation of Arabidopsis plants under normal conditions, salt stress (sodium or lithium chloride), and particularly under osmotic stress (mannitol). Interestingly, plants treated with potassium humate exhibited a reduced antioxidant response and lower proline accumulation, while maintaining photosynthetic activity under stress conditions. The observed sodium and osmotic tolerance induced by humate was not accompanied by increased potassium accumulation. Additionally, metabolomic analysis revealed that potassium humate increased maltose levels under control conditions but decreased levels of fructose. However, under stress, both maltose and glucose levels decreased, suggesting changes in starch utilization and an increase in glycolysis. Starch concentration measurements in leaves showed that plants treated with potassium humate accumulated less starch under control conditions, while under stress, they accumulated starch to levels similar to or higher than control plants. Taken together, our findings suggest that the molecular mechanism underlying the abiotic stress tolerance conferred by potassium humate involves its ability to alter starch content under normal growth conditions and under salt or osmotic stress.
Topics: Arabidopsis; Potassium; Starch; Maltose; Stress, Physiological; Sodium; Plants, Genetically Modified; Gene Expression Regulation, Plant
PubMed: 37569516
DOI: 10.3390/ijms241512140 -
BMJ Case Reports Jun 2019This report describes the case of a 36-year-old woman, gravida 3, para 2, at 11 weeks' gestation, who received a ferric carboxymaltose infusion for iron deficiency...
This report describes the case of a 36-year-old woman, gravida 3, para 2, at 11 weeks' gestation, who received a ferric carboxymaltose infusion for iron deficiency anaemia after medical management of a miscarriage. The following morning, light brown skin staining was noted at the infusion site, and the staining was present 2 months later at follow-up. Skin staining following intravenous iron infusion is a rare but important side effect. The skin staining is potentially permanent but may fade in time. Such an adverse effect may have cosmetic consequences for the patient.
Topics: Adult; Anemia, Iron-Deficiency; Female; Ferric Compounds; Humans; Infusions, Intravenous; Maltose; Pregnancy; Pregnancy Trimester, First; Skin Pigmentation
PubMed: 31175113
DOI: 10.1136/bcr-2018-229113 -
European Journal of Clinical Nutrition May 2014To evaluate the short-term digestive tolerance and glycaemic response of several associations of maltitol and short-chain fructo-oligosaccharides (scFOS) used to replace... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND/OBJECTIVES
To evaluate the short-term digestive tolerance and glycaemic response of several associations of maltitol and short-chain fructo-oligosaccharides (scFOS) used to replace sugars (for example, dextrose) in foods.
SUBJECTS/METHODS
Thirty-six healthy subjects aged 18-60 years were recruited for the study and 32 completed it. The subjects consumed six different mixtures of dextrose, maltitol and scFOS added in a chocolate dairy dessert at a dosage of 35 g. The test days were separated by 2-week washout periods. The subjects reported the intensity of four individual gastrointestinal (GI) symptoms, number of bowel movements and stool frequency for the 48 h following consumption of the dessert. A subgroup of 18 subjects also provided blood samples 2 h after intake to evaluate the postprandial glycaemic and insulinaemic responses.
RESULTS
The composite score calculated from the intensity of flatulence, borborygmi, bloating and discomfort was significantly higher (P<0.0001) for all the desserts containing maltitol and/or scFOS than for the control dessert containing dextrose, but remains at the level of mild effects. The number of bowel movements was also slightly increased (P=0.0006) and the stools were softer (P=0.0045) for the first 24 h but not after (P=0.1373 and 0.5420, respectively). Blood glycaemic and insulinaemic responses were lower for all the sugar-free recipes containing maltitol and scFOS in comparison to the control one (P<0.0001).
CONCLUSIONS
This study has shown that maltitol and scFOS can be used jointly when formulating sugar-free foods with the benefit to lower postprandial glycaemic response with only a small and transient increase in non-serious GI symptoms.
Topics: Adolescent; Adult; Blood Glucose; Cross-Over Studies; Dairy Products; Defecation; Diet; Digestion; Double-Blind Method; Feces; Female; Flatulence; Humans; Male; Maltose; Middle Aged; Oligosaccharides; Postprandial Period; Sugar Alcohols; Surveys and Questionnaires; Young Adult
PubMed: 24642779
DOI: 10.1038/ejcn.2014.30 -
Starch degradation in the bean fruit pericarp is characterized by an increase in maltose metabolism.Physiologia Plantarum Nov 2022The bean fruit pericarp accumulates a significant amount of starch, which starts to be degraded 20 days after anthesis (DAA) when seed growth becomes exponential. This...
The bean fruit pericarp accumulates a significant amount of starch, which starts to be degraded 20 days after anthesis (DAA) when seed growth becomes exponential. This period is also characterized by the progressive senescence of the fruit pericarp. However, the chloroplasts maintained their integrity, indicating that starch degradation is a compartmentalized process. The process coincided with a transient increase in maltose and sucrose levels, suggesting that β-amylase is responsible for starch degradation. Starch degradation in the bean fruit pericarp is also characterized by a large increase in starch phosphorylation, as well as in the activities of cytosolic disproportionating enzyme 2 (DPE2, EC 2.4.1.25) and glucan phosphorylase (PHO2, EC 2.4.1.1). This suggests that the rate of starch degradation in the bean fruit pericarp 20 DAA is dependent on the transformation of starch to a better substrate for β-amylase and the increase in the rate of cytosolic metabolism of maltose.
Topics: Maltose; Fruit; beta-Amylase; Arabidopsis; Starch
PubMed: 36453084
DOI: 10.1111/ppl.13836 -
Food Chemistry Mar 2022Phenolic acids are involved in modulating the activity of starch digestive enzymes but remains unclear if their interaction with enzymes or starch is governing the...
Phenolic acids are involved in modulating the activity of starch digestive enzymes but remains unclear if their interaction with enzymes or starch is governing the inhibition. The potential inhibition of nine phenolic acids against α-amylase and α-glucosidase was studied applying different methodologies to understand interactions between phenolic acids and either enzymes or substrates. Vanillic and syringic acids were prone to interact with α-amylase requiring low half-maximum inhibitory concentration (IC) to inhibit starch hydrolysis. Nevertheless, the initial interaction of phenolic acids with starch somewhat obstructed their interaction with starch, requiring 10 times higher IC, with the exception of chlorogenic and gallic acid. The study demonstrates that 10% of the phenolic acids were retained during starch gelatinization. Those effects were not really evident with α-glucosidase, likely due to the small molecular size of maltose substrate. Phenolic acids with > 1 hydroxyl group like caffeic and protocatechuic acids showed the lowest IC against α-glucosidase.
Topics: Glycoside Hydrolase Inhibitors; Hydrolysis; Maltose; Starch; alpha-Amylases; alpha-Glucosidases
PubMed: 34624776
DOI: 10.1016/j.foodchem.2021.131231 -
PloS One 2018Honey from the European honeybee, Apis mellifera, is produced by α-glucosidases (HBGases) and is widely used in food, pharmaceutical, and cosmetic industries....
Insight into the substrate specificity change caused by the Y227H mutation of α-glucosidase III from the European honeybee (Apis mellifera) through molecular dynamics simulations.
Honey from the European honeybee, Apis mellifera, is produced by α-glucosidases (HBGases) and is widely used in food, pharmaceutical, and cosmetic industries. Categorized by their substrate specificities, HBGases have three isoforms: HBGase I, II and III. Previous experimental investigations showed that wild-type HBGase III from Apis mellifera (WT) preferred sucrose to maltose as a substrate, while the Y227H mutant (MT) preferred maltose to sucrose. This mutant can potentially be used for malt hydrolysis because it can efficiently hydrolyze maltose. In this work, to elucidate important factors contributing to substrate specificity of this enzyme and gain insight into how the Y227H mutation causes substrate specificity change, WT and MT homology models were constructed, and sucrose/maltose was docked into active sites of the WT and MT. AMBER14 was employed to perform three independent molecular dynamics runs for these four complexes. Based on the relative binding free energies calculated by the MM-GBSA method, sucrose is better than maltose for WT binding, while maltose is better than sucrose for MT binding. These rankings support the experimentally observed substrate specificity that WT preferred sucrose to maltose as a substrate, while MT preferred maltose to sucrose, suggesting the importance of binding affinity for substrate specificity. We also found that the Y227H mutation caused changes in the proximities between the atoms necessary for sucrose/maltose hydrolysis that may affect enzyme efficiency in the hydrolysis of sucrose/maltose. Moreover, the per-residue binding free energy decomposition results show that Y227/H227 may be a key residue for preference binding of sucrose/maltose in the WT/MT active site. Our study provides important and novel insight into the binding of sucrose/maltose in the active site of Apis mellifera HBGase III and into how the Y227H mutation leads to the substrate specificity change at the molecular level. This knowledge could be beneficial in the design of this enzyme for increased production of desired products.
Topics: Animals; Bees; Binding Sites; Catalytic Domain; Hydrogen Bonding; Hydrolysis; Insect Proteins; Maltose; Molecular Dynamics Simulation; Polymorphism, Single Nucleotide; Substrate Specificity; Sucrose; Thermodynamics; alpha-Glucosidases
PubMed: 29864156
DOI: 10.1371/journal.pone.0198484 -
Inflammatory Bowel Diseases Mar 2022Iron-deficiency anemia is common in inflammatory bowel disease, requiring oral or intravenous iron replacement therapy. Treatment with standard oral irons is limited by... (Randomized Controlled Trial)
Randomized Controlled Trial
Long-Term Effectiveness of Oral Ferric Maltol vs Intravenous Ferric Carboxymaltose for the Treatment of Iron-Deficiency Anemia in Patients With Inflammatory Bowel Disease: A Randomized Controlled Noninferiority Trial.
BACKGROUND
Iron-deficiency anemia is common in inflammatory bowel disease, requiring oral or intravenous iron replacement therapy. Treatment with standard oral irons is limited by poor absorption and gastrointestinal toxicity. Ferric maltol is an oral iron designed for improved absorption and tolerability.
METHODS
In this open-label, phase 3b trial (EudraCT 2015-002496-26 and NCT02680756), adults with nonseverely active inflammatory bowel disease and iron-deficiency anemia (hemoglobin, 8.0-11.0/12.0 g/dL [women/men]; ferritin, <30 ng/mL/<100 ng/mL with transferrin saturation <20%) were randomized to oral ferric maltol 30 mg twice daily or intravenous ferric carboxymaltose given according to each center's standard practice. The primary endpoint was a hemoglobin responder rate (≥2 g/dL increase or normalization) at week 12, with a 20% noninferiority limit in the intent-to-treat and per-protocol populations.
RESULTS
For the intent-to-treat (ferric maltol, n = 125/ferric carboxymaltose, n = 125) and per-protocol (n = 78/88) analyses, week 12 responder rates were 67% and 68%, respectively, for ferric maltol vs 84% and 85%, respectively, for ferric carboxymaltose. As the confidence intervals crossed the noninferiority margin, the primary endpoint was not met. Mean hemoglobin increases at weeks 12, 24, and 52 were 2.5 vs 3.0 g/dL, 2.9 vs 2.8 g/dL, and 2.7 vs 2.8 g/dL with ferric maltol vs ferric carboxymaltose. Treatment-emergent adverse events occurred in 59% and 36% of patients, respectively, and resulted in treatment discontinuation in 10% and 3% of patients, respectively.
CONCLUSIONS
Ferric maltol achieved clinically relevant increases in hemoglobin but did not show noninferiority vs ferric carboxymaltose at week 12. Both treatments had comparable long-term effectiveness for hemoglobin and ferritin over 52 weeks and were well tolerated.
Topics: Administration, Intravenous; Administration, Oral; Adult; Anemia, Iron-Deficiency; Female; Ferric Compounds; Hemoglobins; Humans; Inflammatory Bowel Diseases; Male; Maltose; Pyrones; Treatment Outcome
PubMed: 33988236
DOI: 10.1093/ibd/izab073 -
Journal of Bacteriology Apr 1996The addition of glucose to maltose-fermenting Saccharomyces cerevisiae cells causes a rapid and irreversible loss of the ability to transport maltose, resulting both...
The addition of glucose to maltose-fermenting Saccharomyces cerevisiae cells causes a rapid and irreversible loss of the ability to transport maltose, resulting both from the repression of transcription of the maltose permease gene and from the inactivation of maltose permease. The latter is referred to as glucose-induced inactivation or catabolite inactivation. We describe an analysis of this process in a maltose-fermenting strain expressing a hemagglutinin (HA)-tagged allele of MAL61, encoding maltose permease. The transfer of maltose-induced cells expressing the Mal61/HA protein to rich medium containing glucose produces a decrease in maltose transport rates which is paralleled by a decrease in Mal61/HA maltose permease protein levels. In nitrogen starvation medium, glucose produces a biphasic inactivation, i.e., an initial, rapid loss in transport activity (inhibition) followed by a slower decrease in transport activity, which correlates with a decrease in the amount of maltose permease protein (proteolysis). The inactivation in both rich and nitrogen-starved media results from a decrease in Vmax with no apparent change in Km. Using strains carrying mutations in END3, REN1(VPS2), PEP4, and PRE1 PRE2, we demonstrate that the proteolysis of Mal61/HAp is dependent on endocytosis and vacuolar proteolysis and is independent of the proteosome. Moreover, we show that the Mal61/HA maltose permease is present in differentially phosphorylated forms.
Topics: Biological Transport; Endopeptidases; Gene Expression Regulation, Enzymologic; Glucose; Maltose; Membrane Transport Proteins; Monosaccharide Transport Proteins; Phosphorylation; Protein Processing, Post-Translational; Recombinant Fusion Proteins; Saccharomyces cerevisiae
PubMed: 8636025
DOI: 10.1128/jb.178.8.2245-2254.1996