Search results for "ERAS"
showing 10 items of 4431 documents
Enzymatic Formation of Raucaffricine, the Major Indole Alkaloid ofRauwolfia serpentinaCell-Suspension Cultures
1991
The major alkaloid from Rauwolfia serpentina cell-suspension cultures, the glucoalkaloid raucaffricine (2), was enzymatically formed from vomilenine (1) and UDPG in presence of microsomal-bound enzyme. This glucosyltransferase exhibits a relatively high substrate specificity with strong preference for 1 and UDPG. The apparent Km values for 1 and UDPG were 40 μM and 0.8 mM, respectively, for raucaffricine formation. Optimum transferase activity was observed at 50° and pH 6.3. The taxonomic distribution of this enzyme seems to be very limited because transferase can he exclusively detected in raucaffricine-producing plant cells.
Interrelationships between Growth Yield, ATPase and Adenylate Kinase Activities inZymomonas mobilis
2001
The presence of cytoplasmic and membrane-bound adenylate kinase (EC 2.7,4.3) as well as inorganic pyrophosphatase (EC 3.6.1.1) was detected in Zymomonas mobilis ATCC 29191. An increase in the molar growth yield (Y X/S ) of Z. mobilis under aerobic growth conditions appeared to be in proportion to a reduction of membrane-bound adenylate kinase (mAK) and ATPase activities and to an increase in cytoplasmic adenylate kinase (AK) activity. Significant (1 - P < 0.01) multiple regressions were observed between the values of Y x (dependent variable), ATPase and AK or AK and mAK as independent variables, suggesting that a combined operation of these phosphohydrolases and phosphotransferases would be…
Two novel oxetane containing lignans and a new megastigmane from Paronychia arabica and in silico analysis of them as prospective SARS-CoV-2 inhibito…
2021
The chemical characterization of the extract of the aerial parts of Paronychia arabica afforded two oxetane containing lignans, paronychiarabicine A (1) and B (2), and one new megastigmane, paronychiarabicastigmane A (3), alongside a known lignan (4), eight known phenolic compounds (5–12), one known elemene sesquiterpene (13) and one steroid glycoside (14). The chemical structures of the isolated compounds were constructed based upon the HRMS, 1D, and 2D-NMR results. The absolute configurations were established via NOESY experiments as well as experimental and TDDFT-calculated electronic circular dichroism (ECD). Utilizing molecular docking, the binding scores and modes of compounds 1–3 tow…
Proteins and enzymes of the peroxisomal membrane in mammals.
1993
Proteins of the peroxisomal membrane can be schematically divided into two groups, one being made up of more or less characterized proteins with generally unknown functions and the other consisting of enzyme activities of which the corresponding proteins have not been characterized. In the present report, these proteins and enzymes are described with the addition of unpublished results regarding their induction by peroxisome proliferators at the post-transcriptional level. Integral membrane proteins (IMPs) can be isolated using an alkaline solution of sodium carbonate. A dozen of preponderant IMPs can be seen on sodium dodecyl sulfate polyacrylamide gel electrophoresis, and the major band c…
Potent SARS-CoV-2 mRNA Cap Methyltransferase Inhibitors by Bioisosteric Replacement of Methionine in SAM Cosubstrate
2021
Viral mRNA cap methyltransferases (MTases) are emerging targets for the development of broad-spectrum antiviral agents. In this work, we designed potential SARS-CoV-2 MTase Nsp14 and Nsp16 inhibitors by using bioisosteric substitution of the sulfonium and amino acid substructures of the cosubstrate S-adenosylmethionine (SAM), which serves as the methyl donor in the enzymatic reaction. The synthetically accessible target structures were prioritized using molecular docking. Testing of the inhibitory activity of the synthesized compounds showed nanomolar to submicromolar IC50 values for five compounds. To evaluate selectivity, enzymatic inhibition of the human glycine N-methyltransferase invol…
Reciprocal Enzymatic Interference of Carnitine Palmitoyltransferase I and Glycerol-3-Phosphate Acyltransferase in Purified Liver Mitochondria
2006
(i) Highly purified mitochondrial fractions were practically devoid of microsomal contamination and of acyl-CoA ligase activity. (ii) In mitochondria, glycerol-3-phosphate acyltransferase (GPAT) activity was supported by two enzymes, the first being very active at low palmitoyl-CoA / albumin ratios and sensitive to external agents (external form), the second being detected only at higher palmitoyl-CoA / albumin ratios and insensitive to external agents (internal form). (iii) Carnitine palmitoyltransferase I (CPT I) activity was shown to inhibit external GPAT activity only. (iv) Glycerol-3-phosphate exerted an inhibitory effect on CPT I, even when GPAT was inactive. Reciprocal interaction of…
tRNA stabilization by modified nucleotides.
2010
Post-transcriptional ribonucleotide modification is a phenomenon best studied in tRNA, where it occurs most frequently and in great chemical diversity. This paper reviews the intrinsic network of modifications in the structural core of the tRNA, which governs structural flexibility and rigidity to fine-tune the molecule to peak performance and to regulate its steady-state level. Structural effects of RNA modifications range from nanometer-scale rearrangements to subtle restrictions of conformational space on the angstrom scale. Structural stabilization resulting from nucleotide modification results in increased thermal stability and translates into protection against unspecific degradation …
Modulation Theory of Adhesion: Role of the Ectoenzymes Glycosidase and Glycosyltransferase
1986
It is amazing, but still plausible, that in all animal systems hitherto studied there is only one basic principle by which cell-cell recognition occurs. From sponges to higher eukaryotes there is only a small number of cell adhesion molecules which are involved in cell-cell adhesion. Specificities and histogenetic patterning are achieved by modulating processes acting on cell adhesion molecules. In sponges (secondary aggregation system) and in other eukaryotes, the activity and function of cell adhesion molecules are assumed to be modulated by enzymatic processes (glycosylation and deglycosylation). Strong evidence from experiments with sponges is available which indicates that modulation c…
Sildenafil protects human mammary epithelial cells against ROS production induced by estradiol
2010
Several studies suggest that xanthine dehydrogenase (XDH) and its oxidase form (XO) play an important role in various types of ischemic and vascular injuries. Recently, we have demonstrated that estradiol (E2) induces a significant decrease of the expression and activity of XDH and of its conversion to XO in human mammary epithelial cells. E2 is known to induce upregulation of eNOS gene expression in aortic endothelial cells. Because the XO-derived O2·- combines with ·NO to yield ONOO-, and considering that ONOO- converts XDH to XO, the resulting increase of XO activity and reactive oxygen species production would eventually lead to a further increase of ONOO- production, thus creating a vi…
Use of two-dimensional thin-layer chromatography for the components study of poly(adenosine diphosphate ribose)
1990
Two-dimensional thin-layer chromatography on cellulose plates has been used for separating and quantifying the three adenosine derivatives: AMP, phosphoribosyl AMP (PRAMP), and (PR)2AMP obtained by venom phosphodiesterase digestion of poly(ADP-ribose). In vitro synthesized polymer, up to 300 derivatives in length were studied. Some parameters of the complexity of poly(ADP-ribose) could be deduced from our results: (i) The first branching point appears in fragments of approximately 21 derivatives in length. (ii) The branching points are located at regular distances of approximately 41 derivatives from each other.