Conformation of Disaccharides
V. S. Raghavendra Rao, Pradman K. Qasba, Petety V. Balaji, Rengaswami Chandrasekaran in Conformation of Carbohydrates, 2019
A disaccharide, by definition, gives two monosaccharides on hydrolysis. It forms by the condensation of the anomeric hydroxyl group of one monosaccharide with the hydroxyl group of the second with the concomitant release of a water molecule. The bonds linking the two monosaccharide units are called the glycosidic bonds and the oxygen atom connecting the two is called the “bridge” or “glycosidic” oxygen atom. Several disaccharides can be derived from a single monosaccharide due to the possibility of a number of linkage types in contrast to amino acids and mononucleotides which can form only one type of dimer. For example, two d-glucopyranoses can form eleven different disaccharides. The conformational analyses of kojibiose, nigerose and maltose have been extended by using “flexible” pyranose rings during energy minimization. The potential energies were calculated using the MM3 force field for both the a and ß anomers and different orientations of the hydroxyl hydrogen atoms were also considered for each anomer.
Biodegradation of Starch
Jean-Luc Wertz, Bénédicte Goffin in Starch in the Bioeconomy, 2020
Leaf starch degradation is initiated by phosphorylation of amylopectin via glucan, water dikinase (GWD) and phosphoglucan, water dikinase (PWD). Dephosphorylation of the phosphoglucans by glucan phosphatases (SEX4 and LSF2) presumably occurs concurrently. In leaves, transitory starch is formed in the chloroplasts during the day and broken down at night. Upon degradation of starch at night, the reduced carbon stored is converted back into a metabolically active state, which can be used by many pathways of the plant. Transitory starch acts as an energy reserve, and an overflow. The first step in the pathway of starch degradation inside chloroplasts must be catalyzed by an enzyme capable of metabolizing polymers at the surface of a semi- crystalline granule, rather than in a soluble form. Maltose produced during starch degradation is exported to the cytosol via a specific transporter rather than being metabolized inside Arabidopsis chloroplasts. The Arabidopsis genome encodes for three α-amylase-like proteins: AMY1, AMY2, and AMY3.
Optical Nanosensors
Vinod Kumar Khanna in Nanosensors, 2021
Nanosensors based on surface plasmon resonance (SPR) and localized surface plasmon (LSPR), including colorimetric devices, are described. Among fiber-optic nanosensors, Fabry-Perot reflectometric optochemical nanosensor employing SWCNTs and optical fibers, in-fiber nanocavity sensor and fiber-optic nanosensors for probing living cells stand out prominently. A nanograting-based optical accelerometer is discussed. Examples of fluorescent pH-sensitive nanosensors are renewable glass nanopipette with fluorescent dye molecules, ratiometric pH nanosensor and pH-sensitive microcapsules with nanoparticle incorporation in the walls. Disadvantages of optical fiber and fluorescent nanosensors for living cell studies are indicated. PEBBLE nanosensors are useful for exploring the intracellular environment. Quantum dots serve as fluorescent labels. Several quantum dot FRET-based probes have been developed, namely probes for determination of protein, protease, maltose and dissociation constant between Rev and RRE. Electrochemiluminescent nanosensors have the capability for remote detection, while crossed zinc oxide nanorods act as resistive UV nanosensors.
Osmotic Nephropathy Resulting from Maltose-Based Intravenous Immunoglobulin Therapy
Published in Renal Failure, 2006
Bobby Chacko, George T. John, N. Balakrishnan, Meshach G. Kirubakaran, Chakko K. Jacob
Intravenous immunoglobulin preparations are being used for an increasing number of indications. To minimize adverse reactions, sugar additives such as sucrose, maltose, and glycine are added to some preparations to serve as stabilizing agents. Intravenous immunoglobulin infusion induces acute renal failure (ARF) via a mechanism of osmotic nephrosis. Most reported cases are related to the use of sucrose-based intravenous immunoglobulin. Herein, we describe a patient with lupus nephritis treated with an immunoglobulin preparation containing maltose who developed ARF with histologic changes characterized by vacuolization and swelling of renal proximal tubular cells. Our case draws nephrologists' attention to the potential of maltose-based immunoglobulin in producing renal failure. Awareness and exercising caution in high-risk groups is elementary to the prevention of this condition.
Trehalose is not a universal solution for solid lipid nanoparticles freeze-drying
Published in Pharmaceutical Development and Technology, 2014
Slavomira Doktorovova, Ranjita Shegokar, Lisete Fernandes, Paula Martins-Lopes, Amélia M. Silva, Rainer H. Müller, Eliana B. Souto
Objective: To prepare stable and easy to handle formulation of solid lipid nanoparticles (SLNs) by freeze-drying with or without cryoprotectants, as appropriate. Materials and methods: SLNs were freeze-dried without cryoprotectants or with cryoprotectants in quantities selected by freeze–thaw test (sucrose, glucose) or literature search (trehalose, maltose). Appearance, re-dispersability and size distribution of re-dispersed samples were evaluated. Results: SLN could be freeze-dried using 10% sucrose, trehalose or maltose. Trehalose was effective in protecting one of presented formulations that was already very stable on its own; its efficiency in protecting other two formulations was limited. Discussion: Our results are in line with various reports of successful freeze-drying of SLN, but considering the stability of original dispersions, no improvement was achieved. Conclusion: We confirmed that trehalose is among the most suitable cryoprotectant for SLN, however it did not improve shelf-life of the most stable formulation.
Effect of vesicle's membrane packing behaviour on skin penetration of model lipophilic drug
Published in Journal of Microencapsulation, 2013
Nurul Fadhilah Kamalul Aripin, Rauzah Hashim, Thorsten Heidelberg, Dong-Keon Kweon, Hyun Jin Park
Disaccharide glycosides synthesised from food grade resources consist of the hydrophilic head group of maltose or lactose and provide better hydrophilic–lipophilic balance (HLB = 12) to the long alkyl chain derived from palm oil (PO) and palm kernel oil (PKO). Maltoside provides more flexibility in the vesicle's membrane because of its low packing density in the bilayer membrane compared to lactoside. The bending of the molecular structure in maltose form a less compact assembly for maltoside, whereas lactose is more linear in shape. Apart from hydrophilic moieties, packing behaviour was also governed by the hydrophobic moieties. PO has higher degree of unsaturation compared to PKO, thus providing higher fluidity in the bilayer membrane. Vesicle with high membrane flexibility is easier to disintegrate and deform to enhance drug penetration into the skin. Results showed that the glycosides delivered vitamin E (VE) into deeper skin layer at least two-fold higher than free VE.
Related Knowledge Centers
- Chloroplast
- Disaccharides
- Glucans
- Food Intolerance
- Congenital
- Recessive
- Physician