Blaško, Jaroslav*
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The biochemical basis of a defective bioenergetic system was attempted to be determined in N,N'-dicyclohexylcarbodiimide (DCCD)-resistant mutant of Methanothermobacter thermautotrophicus. Components participating in the maintenance of methanoarchaeal membrane structure and function, such as the composition of the mixture of squalene and its hydrosqualene derivatives and also properties of membrane-associated proteins were compared in wild-type and mutant cells. The impairment of the bioenergetic system in DCCD-resistant mutant was detectable in the membrane-protein profile; it was also accompanied by changes in proportions of squalene-hydrosqualenes.
- MeSH
- antibiotická rezistence MeSH
- buněčná membrána metabolismus MeSH
- dicyklohexylkarbodiimid farmakologie metabolismus MeSH
- energetický metabolismus MeSH
- membránové proteiny genetika metabolismus MeSH
- Methanobacteriaceae genetika metabolismus účinky léků MeSH
- mutace MeSH
- skvalen chemie metabolismus MeSH
The aim of this systematic study was to analyze the granulometric and rheological behavior of tableting mixtures in relation to tabletability by single tablet and lab-scale batch compression with an eccentric tablet machine. Three mixtures containing 33, 50, and 66% of the cohesive drug paracetamol were prepared. The high compressibility of the powder mixtures caused problems with overcompaction or lamination in the single tablet compression method; due to jamming of the material during the filling of the die, the lab-scale batch compression was impossible. Using high shear granulation, the flow properties and tabletability were adjusted. A linear relationship between the span of granules and the specific energy measured by FT4 powder rheometer was detected. In parallel, a linear relationship between conditioned bulk density and the tensile strength of the tablets at lab-scale batch tableting was noted. The combination of dynamic image analysis and powder rheometry was useful for predicting the tabletability of pharmaceutical mixtures during the single tablet (design) compression and the lab-scale batch compression.
A simple two-step method for the derivatization of polar compounds (lactate, alanine, glycerol, succinate and glucose) using hexamethyldisilazane (HMDS) and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) was developed. This method allows direct derivatization of aqueous samples wihout sample pretreatment. The method was used for the analysis of the metabolites of the unicellular organism Trypanosoma brucei. The limits of detection by GC-MS/MS analysis were in the range of 0.02 mg L(-1) for glucose to 0.85 mg L(-1) for lactate.
- MeSH
- alanin analýza chemie metabolismus MeSH
- glukosa analýza chemie metabolismus MeSH
- kyselina mléčná analýza chemie metabolismus MeSH
- limita detekce MeSH
- organické sloučeniny křemíku chemie MeSH
- plynová chromatografie s hmotnostně spektrometrickou detekcí metody MeSH
- reprodukovatelnost výsledků MeSH
- trimethylsilylové sloučeniny chemie MeSH
- Trypanosoma brucei brucei chemie metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Mycobacterium tuberculosis, one of the deadliest pathogens in human history, is distinguished by a unique, multilayered cell wall, which offers the bacterium a high level of protection from the attacks of the host immune system. The primary structure of the cell wall core, composed of covalently linked peptidoglycan, branched heteropolysaccharide arabinogalactan, and mycolic acids, is well known, and numerous enzymes involved in the biosynthesis of its components are characterized. The cell wall biogenesis takes place at both cytoplasmic and periplasmic faces of the plasma membrane, and only recently some of the specific transport systems translocating the metabolic intermediates between these two compartments have been characterized [M. Jackson, C. M. Stevens, L. Zhang, H. I. Zgurskaya, M. Niederweis, Chem. Rev., 10.1021/acs.chemrev.0c00869 (2020)]. In this work, we use CRISPR interference methodology in Mycobacterium smegmatis to functionally characterize an ATP-binding cassette (ABC) transporter involved in the translocation of galactan precursors across the plasma membrane. We show that genetic knockdown of the transmembrane subunit of the transporter results in severe morphological changes and the accumulation of an aberrantly long galactan precursor. Based on similarities with structures and functions of specific O-antigen ABC transporters of gram-negative bacteria [C. Whitfield, D. M. Williams, S. D. Kelly, J. Biol. Chem. 295, 10593-10609 (2020)], we propose a model for coupled synthesis and export of the galactan polymer precursor in mycobacteria.
A new arrangement of the INCAT (inside needle capillary adsorption trap) device with Carbopack X and Carboxen 1000 as sorbent materials was applied for sampling, preconcentration and injection of C6C19n-alkanes and their monomethyl analogs in exhaled breath samples. For the analysis both GC-MS/MS and GC×GC-FID techniques were used. Identification of the analytes was based on standards, measured retention indices and selective SRM transitions of the individual isomers. The GC-MS/MS detection limits were in the range from 2.1 pg for n-tetradecane to 86 pg for 5-methyloctadecane. The GC×GC-FID detection limits ranged from 19 pg for n-dodecane to 110 pg for 3-methyloctane.
- MeSH
- alkany analýza chemie MeSH
- dechové testy metody MeSH
- lidé MeSH
- limita detekce MeSH
- plynová chromatografie s hmotnostně spektrometrickou detekcí metody MeSH
- reprodukovatelnost výsledků MeSH
- tandemová hmotnostní spektrometrie metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
